Light Cycles and Flowering Cannabis

Rambo January 7, 2012 251
Light Cycles and Flowering Cannabis

In nature, cannabis plants (excluding ruderalis) begin to flower in the late Summer and early Fall. When the days start to become shorter and the nights longer, flowering signals are triggered by photoperiodism, beginning the flowering process. The increasing hours of darkness signal to the plant that Fall is just around the corner. The female marijuana plant shifts its energy from vegetative growth into flowering, in order to attract pollen and produce seeds.  By manipulating the hours of darkness, indoor and outdoor growers can delay flowering indefinitely or begin flowering whenever desired.

The traditional method used to sustain vegetative growth is to keep light on the plants between 18 and 24 hours each day. The key factor is not the hours of light, but the hours of darkness. With six hours of darkness or less, the plants will continue to put on vegetative growth as if they were experiencing an extended Summer.

When it is deemed time for the flowering process to begin, the light cycle is changed to a regimen of 12 hour on and 12 hours off.  The increasing hours of uninterrupted darkness cause the plants to respond as if Autumn is approaching, and begin to flower. By using these two light cycles, you can control when your plants flower.

Over the years I have taught a few people how to grow cannabis. In doing so, I have learned a few lessons myself. Simply telling someone what to do is generally not enough. Unless I also explain the reasons behind the practice, it is usually only a matter of time before they forget or decide to change things up. It also seems to be a lot easier for growers to diagnose their own problems when they have a firm grip on the reasons plants grow how they do.

The Science in Layman’s Terms

Cannabis plants are referred to as long night or short day plants, because they require a long period of darkness to trigger the hormones that tell the plant to switch from vegetative growth to flowering. These light receptors are color pigments in the leaves called Phytochrome Red (PR) and Phytochrome Far Red (PFR). These pigments get their names from the types of light they absorb. PR absorbs red light between 660 and 760 nm and PFR absorbs far red light between 760 and 800 nm. These two pigments chemically react to the light, and trigger the plant to flower or not.

This is where it gets a little confusing.

In cannabis plants, the normal presence of PFR switches off the flowering signal.  The level of PFR is what you can manipulate by adjusting the photoperiod.  PFR is quickly produced when plants are exposed to light that contains far red wavelengths. When there is light, the PFR and PR maintain a balance. When the sun goes down or the lights go out, the darkness gradually switches the PFR to PR. Because of this, PR levels gradually increase and the PFR gradually decrease during the dark period. The presence of PR is a neutral condition to the plants and essentially tells them nothing. When the light returns, or if a small amount of far red light interrupts the dark period, the PR immediately switches back to PFR. If the plant is without light long enough, the PFR will decrease past a tipping point. This decreased level of PFR signals the plants that Fall is approaching; and the plant begins flowering.

In short, the presence of PFR due to long hours of light and short hours of darkness keep the plants in the vegetative phase. If the plant experiences enough hours of darkness, most of the PFR turns to PR  ; and the low level of PFR signals the plant hormones to begin flowering.

Practical Applications

Enough with all of this scientific mumbo jumbo. Let us look at how we can take advantage of photoperiodism.

How to Induce Flowering

Because of photoperiodism, you can easily induce flowering in cannabis plants simply by changing your grow room light cycles–reducing the light from 18 hours a day or more, to only 12 hours each day. Again, what is really important to the plants is changing from six hours of darkness or less to 12 hours of darkness. Within two weeks of switching the light cycles to 12 on and 12 off, you should see small buds starting to form.

I need to stress the point that your plants are very sensitive to any light during the dark period. If you have any light at all leaking into your grow room, during the 12 hours of dark– even momentarily–the PR can change back to PFR.  This means that any light reaching your plants during the dark period may sabotage the flowering process.. For this reason,  you should never–not even for a moment–enter your grow room when the lights are turned off in the 12/12 cycle.

Before you make the switch to a 12/12 light cycle, you need to make sure your grow room has no light leaks. Enter the grow room while the lights are out and close the door behind you. Wait about 15 minute minutes for your eyes to adjust fully, then look around and make sure no light is entering the room. No light under the door, through a curtain, or shining from a CO2 generator or dehumidifier. I have made this last mistake myself. If any of your equipment produces light from the display, cover it with duct tape, making sure no photocells have been accidentally covered.  If you can see your hand in front of your face, you have a light leak that needs to be fixed.

While simply changing to a 12/12 light cycle will induce flowering, there is a trick to jump start the process. Between the switch from an 18/6 to a 12/12 light cycle, let your plants sit in total, uninterrupted darkness for 36 hours. This will cause the PFR to drop substantially, giving the plants a strong signal to flower. After the 36 hours of darkness, begin the 12/12 light cycle. In a side by side experiment, I saw significant results from this method. Be sure to flush out high nitrogen “grow” fertilizers from your growing medium and change to a high-phosphorus “bloom” formula. Also, adding high potassium supplements for the first two weeks can help increase rapid bud development

Light Deprivation For Outdoor

Through manipulation of photoperiodism, growers can induce early flowering in outdoor cannabis plants. It is much more difficult to make the great outdoors artificially dark than it is to turn off the lights–but not impossible. Many growers have perfected the art of light deprivation, and used it to harvest their outdoor crop in midsummer, or even multiple times each year. This can be achieved by building a garden that can be covered after the sun goes down, and then uncovered part way through the morning. If timed correctly, this can lengthen the natural night to a full 12 hours of darkness. The garden must be covered for several hours each day without exception, through the entire flowering period; but the effort can bring impressive early harvests.

Spring Clones

I can’t count how many times I have received urgent phone calls from alarmed acquaintances who planted clones outside too early. Despite what anyone says, clones can do amazing things if properly grown outside. Unlike seeds, however, you need to be aware of the hours of natural light when planting outside. Because clones are likely accustomed to 18 or more hours of light, they often begin to flower once placed outside in early spring. It will depend on your latitude and the strain; but at least in California, the nights are usually too long to plant clones outside before mid-May.

By using supplemental light to decrease the hours of darkness, you can plant your clones outside as early as you like. Simply clip a florescent light with an aluminum reflector onto a stake or cage around the plants. If the light shines on the plant for even a few hours after the sun goes down, it will usually be enough to prevent early flowering. If you are afraid of late frost, you can use an incandescent bulb instead, and also take advantage of the heat it generates.

Power Outages & Light Interruption

Even with light timers and a fully automated grow room, sometimes things go wrong. If the power goes out, or you need to change lights around, keep your light cycles in mind.

When your grow room is running on a 12/12 flowering cycle, a short power outage is not a major problem. A few extra hours of darkness will not really mess things up. Of course, the plants will not grow much without light; but they should be fine for at least two days. Any longer than two days, and they will start to suffer. This will not kill them, but may cause them to become stressed.

When running on a 18/6 vegetative light cycle, a power outage resulting in long hours of darkness can trigger the plants to flower. You need to find an alternative source of light for the grow room. An electric or gas camp lantern will be enough to prevent the PFR from dropping. If you need to change things around and interrupt your normal dark period, just leave the lights on until the following dark period. A few hours of extra light will not hurt anything. Remember, you do not need enough light to keep them growing–just enough to make it not dark.

  • To maintain vegetative growth, use 18-24 hours of light; six hours of darkness or less.
  • To promote flowering, alternate 12 hours of light with 12 hours of darkness.
  • When switching light cycles from vegetative to flowering, first give plants 36 hours of darkness.
  • To harvest outdoor plants early, cut the time light reaches the plants to 12 hours each day.
  • To plant clones outside before mid-May, supplement with artificial light at night to prevent early flowering.
  • During 12/12 flowering, additional dark hours are acceptable if necessary.
  • During 18/6 vegetative growth, additional hours of light will not cause problems.

Successful marijuana growers know how to manipulate the environment of their garden. Once you become comfortable with light manipulation and photoperiods, the sky is the limit.

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Light Cycles and Flowering Cannabis, 4.6 out of 5 based on 67 ratings


  1. Elly110 February 5, 2012 at 5:56 pm - Reply

    I’m a new grower, how do you know when it’s time to start the plant to flower ” When to switch frome 18 hr to 12 hr ? Another words how big does the plant have to be to start this stage? I am growing inside.

    • g.dogg July 27, 2012 at 12:27 am - Reply

      when your plant is about 20 inches is usually a good time to switch into flowering….it is then u change from 12/12 but a good tip is to leave your plants for 36 hours before u change your cycle…this will help in the budding stage.

      • Gmac July 8, 2014 at 2:54 am - Reply

        I have already started my 12-12 cycle, going on day 5
        then i read about the 24 or 36 hr lights out
        can i still do it ? or is it to late ?
        new grower and wanting to learn it the right way, the first time :-)
        plants are 32″ tall and hella healthy
        7x5x8 room under a 600 watt air cooled light
        would love some thoughts on this

    • lucky33 October 9, 2012 at 1:10 pm - Reply

      You asked a Great question that Lots of Beginners and “young style” growers as I call them.Its Most Important that you know what Strain you are dealing with first.All different Strains Need more time to Ved And More Time to Flower.They Can Start to Bud at 6″ or 26″ it all depends on the genetic.If your plant looks yummy switch that thing to 12 and 12 then Enjoy!

  2. Gore February 5, 2012 at 9:19 pm - Reply

    Well that can be a tricky judgement call, there are many factors that need to be considered.

    first, what kind of light are you using?
    higher wattage lamps produce more light and can cover greater areas, also brighter light can penetrate deeper into canopies and is effective over greater distance.

    Second, What strain are you growing?
    Many strains like to double their vertical height after being flipped to 12/12. Kushes are famous for this, diesels too. You don’t want to run out of head room like Big Slugger did in his blue dream grow.

    Third, what is your intention?
    When growers grow “sea of green” they veg their plants for a very short period, perhaps 2 weeks or less. On the inverse there are growers who achieve up to a pound/plant (yes indoor) by vegging much longer.

    So you see it is hard to answer such a vague question. Please provide more information and we will be very happy to help. Or better yet start a growers thread on our forum and show us some pictures so we can better understand what we’re looking at, a picture is worth 1000+ words.

  3. the american bud March 11, 2012 at 11:46 pm - Reply

    Great read simple and to the point. I enjoy the outside and prefer to let nature work its own magic without complicating things.
    A rule of tumb for the beginer about plant hiegth
    1. Always assume your plant will atleast double in hiegth. So if you want a two foot plant start your 12 hour period at 1 ft. Using is approach will allow you to plan your grow space.

  4. 45YrToker March 14, 2012 at 10:46 pm - Reply

    A point regarding height gained during flowering. I think this only happens with plants triggered to flower young. I triggered some indoor White Gold at 2 weeks old & about 10″ tall in a hydro grow, and it hit 5′, & my lights, a month before it was ripe. Had to bend it over, and it got too dense and was lost to mold. But, I’ve planted outdoors as late as 1st of June & early as 1st of March. The most I’ve ever gotten in a height increase after the start of flowering on those has been 4 inches. And that includes varieties, Critical+, Critical Jack, Moby Dick #s 1 & 2, Skunk #1, Power Kush, White Russian, THC Bomb, & my own strain of Indica & my hybrids using Mexican land race genetics & crossing them with existing hybrids, like The Church. Has anyone experienced more than that with plants that old?

  5. 45YrToker March 15, 2012 at 3:45 pm - Reply

    Here is a link to sunrise & sunset calendars. Select your country, then your zip code and then select the month. ENJOY!

  6. Rambo March 17, 2012 at 1:02 pm - Reply

    Recently I watched a friend do back to back cycles of the same blue dream strain. The first cycle he did a normal light cycle switch from 18 to 12 and the plants more then doubled in height. Then next cycle he gave them a full 36 hours of darkness between switching from 18 to 12 hours and the plants hardly put on any further height. There could be another variable that was overlooked, but so far it has not been identified. I’m not sure plant maturity has anything to do height growth after flowering but it could be possible. I think it is more likely that it has to do with strain and light intensity. If the lumens are high enough, the plants will stretch a lot less.

    • Jason September 17, 2012 at 10:02 am - Reply

      Absolutely love the page, dedicating my whole grow op on your advice provided above, its my first indoor grow and im really excited with the results so far, only 2 weeks in (from germination) and they looking pretty. I just have 1 question; How soon is too soon to expose the plant to the 12:12 cycle? Growing in a attic (Roof), going to get a fan up there ASAP and not much to work with, read a comment where the guy said that by exposing the the plant thats at about 1 ft in height being exposed to a 12:12 cycle will cause it to double in length. Sorry if this comment doesnt make sense, quite high at the moment. looking forward to your comment

    • Higgins July 2, 2014 at 6:26 am - Reply

      I planted a see I found in one of my bags and it is about 3 in tall now with 3-4 internodes. When will I be able to see if it’s male or female? I know the female will generate pistils however I’m trying to figure out when this will be so I can identify.


  7. Bud Savage May 4, 2012 at 8:58 am - Reply

    Al plants in nature will usually achieve their maximum height. All plants ( all life period) has a maximum growth. The Liger is one exception as it has no growth regulator and keeps on growing. Once they reach that growth they are done gaining height. Sativas can be up to 20 feet, Indicas are usually 6 feet or so. So you induce flowering at 12 inched lets say. Marijuana is pollinated by the wind in nature, so taller plants will catch more pollen than a shorter one. When you flower at 12 inches the plant knows it has to get taller ( has the genetic capabilities to be taller) so it uses its last bit of veg energy to gain height. Thus you see stretch when you flower. Most indica dominant strains will double in height. Sativas can be even greater. You really need to know what you are growing. I hope this helps.

  8. stoneypaul May 17, 2012 at 12:44 am - Reply

    My timer stopped working (left on) in the 10th weak of flowering 4 at least 2 days. I cut down and dried but tastes like crap if this happens again what can I do?

    • Rambo May 17, 2012 at 11:23 am - Reply

      I seriously doubt that the taste had anything to do with your timers being left on. More likely it had to do with the strain, mold, improper cure, not flushing or something you foliar fed the plants with.

  9. C May 29, 2012 at 4:32 pm - Reply

    The idea of inducing flowering by 24-72 hours of darkness between veg and flower, and the myth of building up resin in 48-72 hours of darkness right before harvest, ARE NOT NATURAL. When you go from 24/0 or 18/6 to 12/12 that is all that is needed to induce. As for the 48-72 hours of darkness before harvest, which I don’t think is mentioned here but applies being it’s a similar subject and many believe in the myth, that does nothing more either. If you wish to mimic nature more indoors a simple method is to switch from 12/12 to 11/13 in late flower to mimic the shorter days of fall and winter. Another myth is in late flower you need more light then 12/12, this is untrue as in late flower the only thing happening is hormonal resin production, not actual bud growth, bud growth has stopped by the final 1 to 2 weeks, so you can go under the 12/12 norm with positive results, but only in the last week or two. It’s amazing the amount of myths and opinions of growing that exist.

    • Rambo May 30, 2012 at 9:24 am - Reply

      When growing indoor the idea is not to mimic the natural world outdoors. The idea behind hydroponics and indoor gardening is to surpass the results of growing in a natural environment. If you want nature, grow outside. Inducing flowering with a solid period of darkness between 18:6 and 12:12 does work to produce a more complete drop in PFR and build up of PR which tells the plant to flower. Is this natural? NO. Does it work to induce flowing faster than a normal light cycle change? Yes. Is it necessary? Not at all.

      As for the other myths you mentioned… I haven’t even heard of these ones, so I would tend to discount them not only as myths, but probably pretty recent ones. As for dropping to an 11:13 light cycle in the last few weeks… I wouldn’t suggest this to anyone. Ultraviolet light creates a chemical change in the plants trichomes that produces THCA and CBDA. You really want as much of this as you can get in the later weeks of flowering. You certainly won’t get more UV light by dropping an hour of lighting. After the plants have decided to flower, as long as the PFR stays below a certain level, the plants don’t really recognize a difference between 12:12 and 11:13 anyway.

      • number3 December 31, 2012 at 6:54 pm - Reply

        The trick is to tweak natural enough so the plant responds positively. Remember the plant knows natural and too far from that is stress….36 hours of darkness is nowhere near close. Stick to changing 18/6 to 12/12 to 11/13, small changes the plants will understand and not stress. Remember the plant has a certain amount of programming from nature over past million plus years, don’t screw with it too much. There is much to be said on this topic, I will try to answer anyone’s questions

    • Drango December 20, 2013 at 2:33 am - Reply

      I love how people say this is a myth and that is a myth because it’s just not natural but yet they say they veg in 24/0 light cycle. I wonder if you even read what you have typed.

      • Anet May 2, 2014 at 1:57 pm - Reply

        Good one. You just gotta laugh. While I’m new to this site, I love it and I am continue to learn. I agree that if you know what the plant can do and you know how to make it do it indoors, then do it. Trial and error is expensive for certain. Prefer 18/6 veg and 12/12 flower myself. Plain and simply. Although I have had power outages force me into 36+ hours of darkness out here in the country. All I noticed was a stressed out me. In nature, the sun doesn’t eclipse for 36 hours. I’d say stick as close to “natural” as you can, but take advantage of these folks personal experiences. Good advice is valuable and free.

    • gaz June 9, 2014 at 5:37 am - Reply

      ty for ur info on the 72 right b4 harvest im having this exact discussion with a friend now , thanks for clearing it up

  10. markieaaryn June 5, 2012 at 8:33 am - Reply

    Thank you for all the information, I was stuck with the myths and was messing up my first grow.

    You guys are very clear thanks again.

    • Rambo June 5, 2012 at 7:11 pm - Reply

      Thank you. We do out best to help people like you along. For more assistance feel free to post any questions you might have in our forum.

  11. new major grower June 5, 2012 at 6:10 pm - Reply

    after googling im starting to grow but im not going extra hard im just doin it for fun i always been able to grow marijuana but i never get it to bud. im jus starting now and im going to try the light trick to see if i can make buds i dont care how much i jus wanna accomplish flowering. ps if yall have any good strands yall can mail me ill appreciate it. or any tips

    i got like 4 plants goin now and one of them has the strongest smell what that mean?

    • Rambo June 5, 2012 at 7:07 pm - Reply

      If you are growing cannabis inside, the switch from 18 hours of light and 6 of darkness to 12 hours of light and 12 of darkness then you should start seeing the early signs of flowering in a week or two. Whether the buds fill in nicely will depend mostly on providing them with sufficient light, feeding them, and keeping them alive. As for the strains. While you are experimenting look for the easier to grow strains that finish in 60 days of flowering or less so you have less time to screw it up. The longer flowering strains like Sour Diesel tend to be better in the hands of more advanced growers. As for mailing strains… I would advice purchasing some clones from a cannabis dispensary in your area, or buying seeds online.

      • new major grower June 6, 2012 at 3:54 pm - Reply


        • tony October 28, 2012 at 1:11 pm - Reply

          y do you have a male in your garden at all unless you are growing seed instead of weed?

          • Rambo October 28, 2012 at 1:33 pm -

            Tony, many growers start their plants from seed. Seeds very often produce male plants. If the person has never been able to get plants to flower as was sated above, there is a good chance the plants would not have shown sex either. While it’s quite likely that they do produce different smells, I doubt the human nose can detect such a subtle difference. I have a friend who thinks he can tell the difference between male and female plants based on the smell alone. I going to call bullshit until proven wrong.

    • STEAMER July 29, 2012 at 10:42 am - Reply


  12. new major grower June 6, 2012 at 7:13 pm - Reply


    • Rambo June 6, 2012 at 11:23 pm - Reply

      No idea why one smells different. Could be a different strain, could be a different phenotype of the same strain. Could be the one that smells is a different sex from the others, or that it has matured faster… There is even a good chance that it means absolutely nothing at all.

      • new major grower June 7, 2012 at 12:03 am - Reply



  13. Gore June 11, 2012 at 2:53 am - Reply

    @ New Major Grower
    It’s important to understand why growers “vegetate” their plants. This is simply to allow the plant to put on some size prior to forcing flowering by reducing light hours. If you where to grow clones or seed without a vegetating period they will begin to flower almost immediately. Because days shorten as winter approaches, your plants will be confused into thinking they need to reproduce in a hurry. The results would be very small plants that produce very little bud.

    Different strains behave differently, some plants will double in height during flowering, others will only put on a few additional inches, it really depends on genetics.

  14. Mark June 11, 2012 at 3:56 pm - Reply

    I was in the flowering stage and my timer messed up, Can I put back into a 36 hour state again?

    • Rambo June 11, 2012 at 4:09 pm - Reply

      Messed up how? Your best bet would be to just go back to the 12/12 light cycles but I suppose if you lights got left on for a long period to time there might be some argument for giving it a 36 hours of dark first. While I don’t honestly know, I suspect a long period of light followed by a really long period of dark may do more harm to the plants than simply dropping back to your 12/12. Either way, watch for herms.

  15. new major grower June 12, 2012 at 6:56 am - Reply



    • Rambo June 13, 2012 at 4:39 pm - Reply

      While we love comments about our articles. Some of these questions have very involved answers and are better asked in the forum.

  16. new major grower June 15, 2012 at 10:58 am - Reply


    • Rambo June 20, 2012 at 10:16 pm - Reply

      Up to date forums? I’m not sure what you mean by up to date, but you are welcome to use the forum on this page. It’s a bit new so there aren’t a ton of people on it but most of the ones who are know what they are talking about.

  17. Peace and Love June 20, 2012 at 6:34 pm - Reply

    I have a question regarding preflowers, any helpful information would be appreciated. on June 5th I placed two clones outside in 5 gal containers( one harlquin and one super sour og). They are both growing rapidly, however the super sour appears to be flowering. Should I be concerned, is it possible this strain preflowers more than other indicas?

    • Rambo June 20, 2012 at 10:00 pm - Reply

      It is definitely true that some strain will start developing flowers long before other. It does seem a bit early for flowering but some plants will show flowering signs but keep vegging strong for months before really flowering. If you want to drive it back into veg you could try breaking up the darkness at night with some supplemental light.

  18. robert downy June 24, 2012 at 5:34 pm - Reply

    what if you went from a 18/6 to a 12/12 without doing the 36 hours of darkness to jump start flowering.. is it okay and still helpful to leave lights off for 36hours? and its within the first couple days of switching light cycle…

    • Rambo June 25, 2012 at 1:29 pm - Reply

      If you have already done a normal switch to 12/12 then I would just leave the plants alone and let them flower. 36 hours of darkness can be helpful but is not necessary. At this point I think confusing them with light could potentially do more harm then good.

  19. cathal June 24, 2012 at 6:03 pm - Reply

    i won,t have any electric 4 two weeks and i have my plants one week into flower . what can i do

    • Rambo June 25, 2012 at 1:32 pm - Reply

      That’s a really tough one. Short of buying a gas generator and running your lights off of it, I’m not sure there is much you can do. If it was just a day or two a battery powered or propane camp lantern would be enough to keep the light cycles correct but I think two weeks with no real light would lead to some pretty messed up plants. If possible, I think your best bet would be to move them outside during the day for 12 hours and back into the dark room at night. Good luck with this one. Let us know if you come up with any creative solutions.

    • tony October 28, 2012 at 1:16 pm - Reply

      Sunlight for two weeks…the sun-power is uhhhh…free!!!!!!!!!

      • Rambo October 28, 2012 at 1:27 pm - Reply

        The questions was posted in June when the days were at their longest. The plants had already be switched to a 12/12 light cycle so they would not have done well if placed outside. While the sunlight is free to many hours of it will either send the plants back into veg, make them larfy, or worse make them herm. The could of course be covered to shorten the hours of sunlight, or brought in and out of the grow room to impose 12 hours of darkness… Lots of work

  20. PG3 June 27, 2012 at 5:00 am - Reply

    hey! first of all im not american, so im sorry for any language mistakes in advance! now, to the point! my plant is in the flowering stage for about 3 weeks now. i switched to 12-12 and within 3 days it was clear i was lucky enough to have a female plant. buds started to develop, plenty of white hair etc. then i had to leave for 1 week, and my friend who was supposed to take care of it, accidentaly switched off the timer. as a result, my plants suffered bout 5 days (!!!) of constant light and heat (i live in a pretty hot country during summer) during their very first days of flowering. since then i dont see any significant development in the buds. some brown hair showed up, but still, buds arent growing for the last 10 days or so. Also, i wasnt aware they need absolute dark so i didnt check it out the way u suggest. i assumed that since lights are off, they have what they need! anything to suggest? any way to save it?! thank you..

    • Rambo June 27, 2012 at 9:37 am - Reply

      The constant light for 5 days would have sent the signal to the plants that they should go back to vegging instead of flowering. This back and forth in addition to the extra heat has probably shocked the plants a bit. You have two options, you can switch back to 12/12 and at some point they should start to flower again, or give them the 36 hours of darkness followed by 12/12 and hope for the best. At this point the 36 hours may just confuse and stress the plants even more so I’m not sure its a great idea. Sometimes these things happen. Wish I could be more help. We’ll cross our fingers for you.

  21. PG3 June 27, 2012 at 10:52 am - Reply

    i did set them right back to 12-12 as soon as i got back to my place! that was bout 10 days ago but i cant notice any real progress since then! i think i ll keep it for another 10 days and if no progress made, i ll let it…rest in peace! Man growing that plant is a real pain in the ass regarding the level of difficulty and sensitivity! thanks for the info!

  22. Rene' June 27, 2012 at 10:23 pm - Reply

    Please Help! I’m at 9wks of flowering Mr. Nice and the lighting schedule (timer issues) must have varied enough to cause my plants to start to return to veg. I should be harvesting in a week or two…. Should I harvest early? Cut light back? Shut lights out for a bit? Help please!! They look awesome but new little green nodules look kinda alien like. HaHa

    • Rambo June 28, 2012 at 11:01 am - Reply

      First I think we need to know more about these timer issues. Even plants given 13 hours of light will generally still flower. Of course if you have been sneaking in the grow room every night with a flashlight then you have been interrupting the darkness and this could certainly screw them up. As for them returning to veg… Im not sure what you are seeing, but a picture in the forum would probably help more then 1000 words. While I have never grown Mr. Nice before, my understanding is that it is a 8 week (60 day) strain. Many plants that have fully matured buds but are allowed to continue flowering will begin to open up again, thought usually not after only an extra week. Tight buds can suddenly begin to open up and begin new growth. Take a magnifying glass and check out the trichomes, if they are becoming milky or amber instead of clear, it’s time to harvest. Changing the light cycle at this point isn’t going to do a bit of good. If you decide to keep flowering, keep them at a 12/12 but your about done anyway. Very few strains take longer then 10 weeks indoors. Good luck.

    • Rambo June 28, 2012 at 11:23 am - Reply

      Further research and I’m finding that Mr Nice is a 9-10 week strain. Still, I think you are probably close to done and can safely harvest without sacrificing much potency.

  23. DarkStar June 28, 2012 at 12:01 am - Reply

    I accidently set my veg timer to 12-12 for two days..then when I reliezed what I did I switched it back to 18-6. What do you think I should expect happen?

    • Rambo June 28, 2012 at 11:03 am - Reply

      I think you will probably start seeing some flowering signals, but as long as you keep them on 18/6 and keep them on high nitrogen nutrients they should snap out of it. This is a common way for outdoor seed growers to sex there plants early long before the normal switch from veg to flower in early august.

  24. karen June 28, 2012 at 12:55 pm - Reply

    I started several tga subcool strains from side indoors andf vegged for about 3months. Then i put them in greenhouse in end of april and they got huge and began flowering in mid-may. Now at end of june, some not all are reverting back to veg. When they do eventually finish up will the reverted ones have an inferior yield because of its confusion?

    • Rambo June 28, 2012 at 1:32 pm - Reply

      You’ve made the same mistake that many growers make. It’s fine to start early inside and move out into a greenhouse or into the ground but if done before about mid May, you’ll need to add a few hours of supplemental light to make the days long enough to keep them from flowering. This is not a problem with seeds, but clones will start flowering almost every time. The supplemental light will prevent this until the days are long enough to keep them in veg. As for dealing with the problem… you have two options. You could keep them flowering and do an early harvest with light deprivation, or you can wait and see what happens. Really it will depend on how far into flowering they were before they went back to vegging. I expect it will diminish your fall harvest considerably if they were far along… but you never know. It’s a hard lesson to learn, but your not the first, and you won’t make that mistake again.

      • Bill July 6, 2012 at 4:04 pm - Reply

        I do this nearly every year, it gets them sexed, then they grow more and then produce a bunch of well developed buds. Just make sure you keep them well nourished for such a long grow.

  25. DarkStar June 28, 2012 at 7:08 pm - Reply

    Thanks Rambo..even if it might have been 3 days? Thanks again..There deffinantly in shock but have my fingers crossed..PEACE

  26. dez July 9, 2012 at 4:13 pm - Reply

    I have been going a couple years now but have had some bad luck lately. let me tell u i have a 8×8 tent, filled it with babies i mixed ss early budd with jackhearer. now i pushed them to sex them then vegged, then flower. they all looked diff but the more shorter ones were beautiful and fat. then all of a sudden BAM, no more growth, then i saw seeds. harvested early. i at no time seen it coming. it was potent but tasted like garbage. now i am doing in and out and i have 4 outta many in full cola bloom, why? i was terrified to turn them herrmy soo i bring them in early but not the same time due to work so sometimes they r in 15hrs of night. they look amazing but am i at risk. sorry so long. Dez

    • Rambo July 9, 2012 at 5:47 pm - Reply

      Dez, I wish I could help, but I don’t have a really clear picture of what you are up to. Let me see if I have this right. You crossed ss early bud and jack that you started from seed and decided to sex them before allowing them to veg. Then you planned to go back to veg after sexing but they wouldn’t grow any larger and instead they started to flower out, but then you found seeds so you harvested early. Either you missed a few mails or you had some plants herm on you. This could be from a lot of things you are doing wrong, or possibly the genetics you created from the cross or the parent genetics have a predisposition to herm. As for why they stopped growing… it seems pretty evident that they didn’t like being sexed, so I would suggest not pre sexing them if you are going to grow from seed. Let them sex themselves or grow from clone.

      So now you are doing indoor and outdoor with the same strain and 4 of them are in full cola bloom. This makes me think you may have unlocked some kind of recessive determinant gene from some long lost ruderalis heritage and they are wanting to flower regardless of hours of light. I’m not really sure what this has to do with your fear of them herming though. I apologize for not having a clear cut answer, but honestly I’m not even sure I know what your questions is. The more articulate you are with your questions the easy they are to answer. In the future, the forum is probably a better place for longer questions like this.

  27. dez July 9, 2012 at 9:01 pm - Reply

    My question is can the four i bring in to create longer night cycle screw up my plants because it is diff everyday but never short enough to revert back to veg?i mean outta 50 outdoor 4 are in full bloom and they get direct sun all can a plant have too much darkness?

    • Rambo July 9, 2012 at 9:18 pm - Reply

      If they are in full bloom, I’m not sure how much good it will do to extend the hours of daylight, but it’s worth a try. It’s possible you can talk them into vegging again but upping the light to 18hours a day. Remember, you don’t necessarily need grow lights for this, any light with some red in the spectrum will do. You could even leave them outdoors and give them a shop light or something. If the plants already have some size to them, you might consider keeping those four in flowering with a light deprivation system. To many hours of darkness won’t really hurt a plant, but it will make them flower, and even they don’t receive enough light they won’t grow or flower very well. Hope this helps

  28. dez July 10, 2012 at 2:33 am - Reply

    Thanks for the info,yes my plan was to keep these going in bloom but i was hesitant because my darkness fluctuates

  29. jen July 13, 2012 at 9:00 am - Reply

    I thought males made themselves known early, meaning, even in veg state they start to change before the ladies. I grow outdoors and lost track of month because of the season lol and my Sativas are almost 3 Ft tall flowering now on week 3 but it took 3 months for 3 of my 5 plants to show their balls

    Any advise would be great

  30. Kevin July 15, 2012 at 7:20 am - Reply

    Best way to cover the smell indoors?

  31. Bonny July 15, 2012 at 2:48 pm - Reply

    I am 6 weeks into my light dep. Is it OK to leave the tarps off all day/night now?

    • Rambo July 15, 2012 at 6:00 pm - Reply

      I guess it really depends on the number of hours of daylight/darkness at your latitude. If your nights are long enough then it should be fine. On the other hand, if you are only a few weeks away, why risk it?

      • Bonny July 18, 2012 at 9:22 pm - Reply

        I am in northern california and can not be home to cover for 5 nights. Wondering if I should continue to cover after those 5 nights? Also is the extra sunlight beneficial in any way?

        • gore July 19, 2012 at 1:16 am - Reply

          Hi Bonny,
          Missing 5 days of covering your dep house is unfortunate but not disastrous. The worse case scenario is that the plants will begin to vegetate again during this time, and then revert back into flower after you return to your schedule. Please excuse the expression but I often refer to this condition as “photofucked”. This refers to buds that have begun to branch out, the result is hundreds of tiny crystal covered branches instead of tight flowers.

          I’m tempted to recommend that you leave them covered while you are out and just stick a 4 foot florescent light in the enclosure on a timer, but the forecast calls for higher temperatures in the following days and that could cook them.

          If stepping out for a few days is unavoidable and there is no one you can ask to cover the plants, they you have few options, I think they should be alright. Best of luck on your dep project and I hope you have a wonderful time while you are out.

        • Rambo July 19, 2012 at 9:56 am - Reply

          I’m going to agree with Gore. Currently the sun is up for about 14.5 hours between sunrise and sunset. This is not an ideal day to night ratio for flowering. I suspect they plant will wonder what the hell is going on, but probably not respond to poorly over only 5 days. I think if you are already pretty deep into flowering then you should be fine.

  32. elkamino July 15, 2012 at 3:26 pm - Reply

    I’m a 3rd-year med grower in Montana with 3 plants about 5′ tall in a greenhouse. Autumn comes on cold and fast and I’ve found my plants struggle to finish, so I’d like to get them flowering just a week or 2 early via light dep, but then allow the shorter natural days to take over. Is this possible?

    I have seeds grown by a former caregiver (MT’s law has changed drastically for the worse and my options were limited) but they’re all sisters of an 8-ish week strain – his “Honeymoon A” x with a Sour Bubble dad.

    So the question: How do I know when they’ll begin flowering but NOT revert to veg after I stop with the light dep?

    Thank you in advance for any help!

    • Rambo July 15, 2012 at 6:06 pm - Reply

      In California seed start plants will usually start flowing on their own around August first. This is of course dependent on the strain but its a pretty safe general rule. I think if you started with a dep right about now, you can probably go back to natural light by about mid August without taking any real risk at reverting back to Veg. I would say this is playing it safe, and you might be able to get away with a lot less dep time. Remember, cool nights are usually not the problems for finishing up. It’s usually more of not enough days of intense light in the summer. This is particularly true of more equatorial sativa strains. You might have more luck with a higher altitude indica strain.

  33. Qtrues July 20, 2012 at 2:46 pm - Reply

    Can i start the flowering process after only 2 days of vegetation?

    • Rambo July 20, 2012 at 5:30 pm - Reply

      You certainly can, but with only two days of veg I would probably not expect very large plants. Even in see of green (SOG) setups, I usually see people doing at least a week of veg to help get the roots established.

  34. will July 24, 2012 at 2:18 pm - Reply

    I started plants the end of April. I had one plant get to 12″ and then bud. It has only grown about 3 since budding. All the other plants are in normal cycle. I took the height challenged one inside at night allowing only a 12/12 cycle. I’m not optimistic about it growing any larger but…I’m not sure what may happen, bringing it to a 12/12, but it does look nice and swewt smell. BTW, I’m unsure of the strain. I’m thinking it could be a low height strain. Any ideas?

    • Rambo July 24, 2012 at 3:04 pm - Reply

      Not sure what happened to that little one. It could be some auto flowering genetics got worked in at some point.

  35. Jacob July 30, 2012 at 11:58 pm - Reply

    I got a plant thats about a foot tall and Iv had it outdoors for about 2-3weeks. I’m about to bring it inside and put it under 12/12 and I was wandering how long does it take for the buds to actually start forming. And how long will it take for the buds to actual get decent size where I can be done with the plant and harvest it.
    Any ideas or suggestions??

  36. gore July 31, 2012 at 8:19 am - Reply

    There are a few factors that you did not mention on your question, most importantly perhaps, is what strain it is. Indica land-races will form flowers and ripen faster than Sativa land-races. In general you should begin seeing flower formation in 2-3 weeks and the plant should be ready for harvest 8-10 weeks after 12/12. Please remember that these numbers are generalized and you should expect your results to vary.

  37. Yuriboyka July 31, 2012 at 4:39 pm - Reply

    ive been growing my baby for three months outside. Its 3ft tall, beautifil, and the smell is amazing. unfortunatlly i have no buds. how can i start 12/12 if my plant has been outside the hole time? Please help!!!!

    • Rambo July 31, 2012 at 4:48 pm - Reply

      There is no reason for concern. Many outdoor plants don’t begin to flower until early August or sometimes even later. If you want to induce flowering early, you can use light deprivation to reduce the hours of sunlight and shorten the day. I’m not sure I would recommend it at this point though. Just let them do their thing and be patient.

  38. Yuriboyka July 31, 2012 at 7:36 pm - Reply

    I started may plant in May outdoors. Will it produce buds naturally without light deprivation?

    • Rambo July 31, 2012 at 7:43 pm - Reply

      Don’t over think it. It’s a plant. They flower on their own in the wild just fine. As long as the plant is getting plenty of light, water, fresh air, and some kind of fertilizer you should be just fine.

  39. Yuriboyka July 31, 2012 at 7:48 pm - Reply

    but dnt know the strain.

  40. Yuriboyka July 31, 2012 at 7:55 pm - Reply

    Its growing so tall it’s getting hard to hide. I have mirrors surronding it for extra light. Hopefully if i let it be, and do it’s thing outside it will produce.

    • Rambo July 31, 2012 at 10:19 pm - Reply

      I don’t seem to be able to give you the answer you are looking for. I suggest you take your delima to our forum so others can try to help you.

    • tony October 28, 2012 at 1:18 pm - Reply

      won’t reflecting the light with a mirror produce heat?

      • Rambo October 28, 2012 at 1:23 pm - Reply

        Yes. Mirrors can create hotspots which can damage plants. Flat white materials usually reflects the most light and work much better.

  41. Chris August 1, 2012 at 12:23 am - Reply

    This may be off topic but I got a clone that’s not very tall but I just now transplanted it into a bigger pot and brought it outdoors and I looked at it today and the leaves are all droopy down. Is it about to die or something? I know for a fact I didnt over water or under water it, so i dont know caused it but any suggestions on how to make the leaves stand straight back up…

    • Rambo August 1, 2012 at 3:29 pm - Reply

      Yes this is off topic and better suited for our Forum. Take it out of the sun and make sure it has plenty of water. The plant is most likely in shock from being transplanted to roughly and needs a few days to adjust.

  42. jr August 2, 2012 at 9:48 am - Reply

    Just a curious question when u switch into flowering is there anyway u can trick ur plants? For instance let the lights go 24hrs one day on an the next day 24 hrs off.. or every 6 hrs switch the lights on and off. An if so what are the results????

    • Rambo August 2, 2012 at 10:49 am - Reply

      Sure you can trick the hell out of them with whatever light cycle you want and results will vary based on hours of darkness. Read the article again and I think it answers all of these questions. 24 on and 24 off will produce flowering, and 6 on and 6 off will keep them in veg. The hours of darkness is what is important, not the hours of light.

  43. jr August 2, 2012 at 4:19 pm - Reply

    So ur saying that I can do 24on/24off for flowering? I’m a beginner an just tryin to get certain tips on things! As far as my veg stage I’m gonna keep it 18/6. I wanna try something different as far as the flowering stage to see which way will produce more progress then just 12/12. So as for the 6 on 6 off id probably be better off doing a 6 on 12 off an 6 on again or 36 off 12 on? Like I said I’m a beginner an trying to learn different things that’s all…

    • Rambo August 2, 2012 at 4:41 pm - Reply

      you could do 24/24 or 6/6 but that is a lot different that me suggesting that you should. If you are just learning the ropes don’t try to reinvent the wheel. You have a pretty steep learning curve as it is. 18 on 6 off for veg, 12 on 12 off for flowering. Don’t make it more complicated then it needs to be.

  44. amishtaffy August 9, 2012 at 1:41 am - Reply

    when starting to flower, what is the best hour to start the new 12/12 cycle? If my veg cycle was 6am-1am would it be best to start the new flower cycle at 6am, ending at 6pm or to start it at 10am, ending at 10pm?

    • Rambo August 9, 2012 at 11:23 am - Reply

      All other things being equal your plants won’t really care. The biggest factor here should be what hours are convenient for you to work in the garden. If you go to work at 8 am and don’t get home until 6pm then you’ll probably want those extra evening hour with the lights on to get you chores done.

  45. gore August 9, 2012 at 8:55 pm - Reply

    In addition to what Rambo mentioned, consider temperature. Some growers prefer to run their lamps in the evening when it’s cooler.

  46. laffytaffy August 12, 2012 at 8:28 pm - Reply

    my buds are just about done was just wondering whens the best time 2 harvest them in their light cycle or dark cycle and is not watering them for a few days before harvest good idea?

    • Rambo August 13, 2012 at 8:38 pm - Reply

      Water the plants up until the day of harvest. However you can stop fertilizing up to a week before harvest to allow the plants to flush out some stored nutrients. Terpenes build up during the dark period and begin evaporating under the strong light, harvesting just as the light come on and then drying in a dark or dimly lit area will help preserve these terpenes.

  47. OMMP August 13, 2012 at 7:06 am - Reply

    Just had a quick question.. I leave my (indoor) flowering tent open during the lights on period, for ventilation, and zip it back up before lights out (it is in the the same room as vegging plants). The last two nights I have been roughly 5-10 minutes late zipping it back up, and I am concerned about hermies popping up as a result. Should this be a concern, or am I over-reacting? I have plants in early, mid, and mid-late flower. Any feedback would be helpful.

  48. gore August 13, 2012 at 8:17 am - Reply

    The practice of leaving manually opening doors to 12 hour rooms is a common one. Many growers resort to this routine to help mitigate high temperatures. If you are a few minutes late, it should not be a big deal, but it’s not ideal either. Make every attempt not to be late and consider upgrading your cooling system so that you no longer need to open the tent door. Another option may be to run your 12 hour room at night when it is cooler.

  49. Trycee-Marie August 22, 2012 at 4:35 pm - Reply

    Question my unkle left these plants in the back yard… I just moved into his old house. the plants are about like 5 or 6 ‘ tall. He said i can have them. i want some bud but I am so clueless how to do it! Im willing to learn if poss. I just want me some bud :)

    • Rambo August 22, 2012 at 4:53 pm - Reply

      We would be more then happy to help you with your questions. Join the forum and ask away.

  50. tony August 23, 2012 at 3:38 am - Reply

    hello mate i just want to know how long i can keep the lights 18/6 till i go to 12 / 12 and how long i can keep 12/12 do i need to untill the last day, many thanks mate

    • Rambo August 23, 2012 at 6:55 am - Reply

      Keep the light on 18/6 until you want them to begin flowering. Keep the light on 12/12 until you harvest.

  51. bobby August 23, 2012 at 7:34 pm - Reply

    Hi guys,
    I’ll need to change my light schedule. Right now the light is ON from early in the morning to the night. for this weekend, I’ll need to put the light ON during the night and then get it back to “normal” cycle. Do you think it will be bad for the plant? By the way, i’m in vegetative mode and the plant is 9″ tall.

    • Rambo August 24, 2012 at 2:20 pm - Reply

      I’m not certain of what you are trying to do but it sounds like you want to keep the plants in veg but you want to switch from running the lights during the day to running them at night and then back to running them during the day after the weekend is over? This won’t hurt the plants as long as the transition doesn’t give them periods of darkness over about 12 hours.

  52. gore August 25, 2012 at 1:30 pm - Reply

    This concerns me, an abrupt change like this could create stress, and stress can create hermaphrodites. I think it may be safer to simply leave the lamps on through the plants “old” night, and when the plants “new” night comes around, begin the new photo-period. When plants are in veg, it’s always safer to burn lamps for more hours, rather than less.

    Furthermore, because of the way Marijuana plants photosynthetic metabolism works, the plants does not benefit from a dark period at all. Many people argue that their plants need to “rest” but this is a misunderstanding. Instead, throughout veg, periods of darkness for up to 6 hours serve to mitigate heat generation and reduce electrical consumption.

  53. chaz August 30, 2012 at 1:40 am - Reply

    Hello have some plants that started to bud last week when do I harvest theres no male present looks to me like 2 different types of weed thanks 4 any information

    • Rambo September 1, 2012 at 2:47 am - Reply

      You probably have between a two and three month wait ahead of you. I know it’s hard to be patient, but if you keep giving them plenty of light, food and water, they will take care of you as well. Once the buds have filled in, keep an eye on the trichomes and look for mushroom heads on them that are turning from clear to milky or amber. This will mean that the cannabinoid production is at its peak… time to harvest.

  54. Jimmy August 30, 2012 at 2:27 pm - Reply

    How do I make buds more dense or longer life span to get bigger …..already got buds started small and want them to fill out as much as I can let them what’s the cut off

    • Rambo September 1, 2012 at 2:44 am - Reply

      Jimmy, Just keep giving them good food and water and keep them on a 12/12 light cycle for another solid two months. They should do the rest on their own. You’ll know they are ready to harvest when the trichomes under magnification start to balloon up at the ends like mushrooms and look a little cloudy white or amber colored.

  55. Jimmy August 30, 2012 at 2:29 pm - Reply

    Do I leave the lights at 12 12 or do I add more sunlight to let buds grow better?

    • Rambo September 1, 2012 at 2:42 am - Reply

      Keep it at 12/12 through the end of harvest. While monkey business with light cycles is not totally foreign to me, and a solid grow technique can accommodate slight variations, keep it simple. 12/12 will get you where you want to go every time.

  56. Jimmy September 1, 2012 at 3:41 am - Reply

    Any certain Food or fert I should give them ? What is the number for the fert ….got some 19-19-19 would be good for it or no?let me kno what ur advice is for flowering ferts

  57. Jimmy September 1, 2012 at 5:54 am - Reply

    Also should I dim my light I have dim able blasts there is a 50% a 75% and a 100% what setting would be the bests for the flowering stage

  58. Jimmy September 1, 2012 at 6:19 pm - Reply

    Would it bother plants that were grown outside if I bring them inside and finish the flowering with my indoor plants?

  59. gore September 4, 2012 at 7:10 am - Reply

    @ jimmy

    Please bring your questions to the forum. The blog roll is intended to be kept on the topic of its hosting article.

  60. Jimmy September 4, 2012 at 12:51 pm - Reply

    K sorrry

  61. zach September 6, 2012 at 5:51 pm - Reply

    hello ,i have a qustion about my plants. today i was looking at my plants and i decideed i was going to pick 1 of them because it was looking pretty bad. when i went to cut the leaves around the bud i saw that there was like little bulb type looking thing and their was alot of seeds in most all of them, what is this and did i pick to early

  62. DENNY September 7, 2012 at 7:36 pm - Reply

    ok this is my first run and i let my plant get about 2 feet them put it into flower heres the problem i ran both light cycle s 12-12 is there hope still and no i did not wait 36 hours before putting into flower please tell i am ok thanks

    • Rambo September 16, 2012 at 4:01 pm - Reply

      Here is the problem? I don’t understand your problem. If your plants are two feet tall and you switched them to 12/12 then you did exactly what you were supposed to… 36 hours of darkness is optional. Its really not that complicated. If this does not answer your question, please clearly and articulately post your question in the forum

  63. tribud September 16, 2012 at 9:32 am - Reply

    I am just now getting buds
    on mine is it to late will the produce still?

  64. kp September 16, 2012 at 5:34 pm - Reply

    I have 4 plants that are in the flowering stage almost at week 6 their doing really well. Tall, green and nice juicy buds but I have a problem I live in an apartment and their doing inspections.. so my question is can I box my plants up during the lighting cycle and keep them in the dark a couple hours later to transport them and what’s the worst possible scenario when doing such things.

    • Rambo September 16, 2012 at 5:48 pm - Reply

      It would be best to box them up while they are supposed to be in the dark period of the 12/12 but if you have to box them up during their scheduled light period it probably will not be a problem. Just be sure they don’t get to hot sitting in a car or something.

  65. Jason September 17, 2012 at 10:04 am - Reply

    Your comment is awaiting moderation.

    Absolutely love the page, dedicating my whole grow op on your advice provided above, its my first indoor grow and im really excited with the results so far, only 2 weeks in (from germination) and they looking pretty. I just have 1 question; How soon is too soon to expose the plant to the 12:12 cycle? Growing in a attic (Roof), going to get a fan up there ASAP and not much to work with, read a comment where the guy said that by exposing the the plant thats at about 1 ft in height being exposed to a 12:12 cycle will cause it to double in length. Sorry if this comment doesnt make sense, quite high at the moment. looking forward to your comment

    • Rambo September 17, 2012 at 4:58 pm - Reply

      Exposing the plant to 12/12 or beginning the flowering cycle will not in an of itself make the plants double in size. However, they will continue to grow in size after they have been switched to the 12/12 light cycle. Depending on the strain, the light intensity, fertilizer used, temperature, air flow and other factors, the plants very well may double in size or more by the time they are ready to harvest. With this in mind you should switch to flowering so they will finish with at least a foot of room between the light and the tops of the plants. Take the distance between the top of your growing medium and the max height of you bulb, then subtract a foot and divide by two. That should be about the max height the plants should be when you switch. You can always switch sooner, or wait longer and tie them down or top them for a wider plant with more tops.

      • Jason September 19, 2012 at 9:46 am - Reply

        Great thanks for such a detailed answer, just about the “How soon is too soon for the plant to be exposed to the 12:12 cycle? I understand leaving it to become more mature yields better results but just want to know how soon i can let them “start” budding. Thanks again for all your advice. Regards from South Africa

  66. chaz September 22, 2012 at 4:54 pm - Reply

    hi u talk about amount of light during bud stage does moonlight affect this ie. full moon. should I cover outside plants even with streetlights / neighbors lights etc

    • Rambo September 28, 2012 at 7:01 pm - Reply

      Good question. Street lights and neighbors lights can definitely affect your flowering cycle. The moon on the other hand will not create problems with flowering. I assume this is because it reflects very little if any red light.

  67. killBill September 28, 2012 at 5:13 pm - Reply

    No question just want to thank you Rambo and Mr Gore.Best advice I have found in all my studying.You guys ROCK!!!

  68. olly October 21, 2012 at 4:29 am - Reply

    hi i have started flowering my plant 2 days ago and i didnt leave it for 36 hours i went to 12/12 is this okay.

    • Rambo October 21, 2012 at 9:29 am - Reply

      Olly, Giving your plants 36 hours of darkness between the veg and flowering light cycles helps to induce flowering more quickly but it is not necessary at all. It is a “trick to jump start the process.” Simply changing from 18/6 to 12/12 will work just fine, it just may take a few days longer to notice a strong flowering response.

  69. Cunikeq187 October 22, 2012 at 2:39 pm - Reply

    Hello there i might sound a little bit weird, i have started my little growing room, but i m stock at the lights can any one of you guys help me with this problem that i have, i wanted to know what kind of light i can use from the seeding light , till the end. HELP

    • Rambo October 22, 2012 at 3:25 pm - Reply

      There are not weird questions. We are here to help if we can. If you want to use one light from seedling through the end of flowering then a High Pressure Sodium light is the way to go. These usually come in 400, 600, or 1000 watt sizes depending on the size of your room. HPS lights require a ballast to keep the light from drawing to much power and these ballast are available in two varieties. The older and less expensive style uses magnets while newer design is all digital. Digital ballasts produce less waist heat and make less noise and reportedly produce brighter a light. Go with the digital ballast if it’s in your budget. You may be able to find these used on Craigslist. As for the size of the light, it depends on your growing area. 1000 watts covers about a 4 foot by 4 foot area, 600′s can almost pull off that much growing area, maybe a bit less. The 400′s are probably best for a few plants, no more then a 3×3 area.

  70. Cunikeq187 October 22, 2012 at 3:36 pm - Reply

    Thank you for responding back, k i got this , how about from the seed what should i use? Cfl are good for the first 3-4 weeks, and after that i can go with 600 watts Hps

    • Rambo October 22, 2012 at 3:40 pm - Reply

      A CFL is fine from seed to the first few weeks. Your CFL’s will work fine if you keep them 6 inches from the tops of the seedling

  71. Cunikeq187 October 22, 2012 at 3:49 pm - Reply

    one more question for today and i m done lol. Any kind of (led) can grow them right? and how about 120 watts led; are they good after i use Cfls for the first few weeks

    • Rambo October 22, 2012 at 3:53 pm - Reply

      I have a feeling this won’t be the last questions. How about opening a thread in the forum

  72. uknome October 23, 2012 at 12:36 pm - Reply

    I waited quite a bit longer than I perhaps should have to start flowering. (made switch at 21ins). and now i hav a plant quickly outgrowing its room. is there any way to slow growth down. It has been 2wks, im gettin sm buds forming but im worried it will outgrow the lights, which are maxed in heighth, before flowering is complete. any advice?

    • Rambo October 23, 2012 at 10:25 pm - Reply

      I think most of us have been through this situation at least once or twice. Your best bet at this point is probably to try to tie the branches down. Here is an article I wrote that may help you out. You could also post your question in our forum and you might get some further ideas from the community.

  73. uknome October 24, 2012 at 5:14 am - Reply

    Thanx alot for the link. I have already topped it about a wk and a half ago. it still seems to be stretching but seems lik it might be slowing down, i hope. If I pinch the tip now this far into flowering wil it cause a prob? And do u think the 4-12-4 fertilizer I’m using, mixed 75% strength is an ok food for flowering? It was the closest I could find in my area. There are no major grow stores near me. Sorry to ask so much, lol, iv just read most ur articles and they seem to be more benefitial, and accurate than most any site

    • Rambo October 24, 2012 at 9:25 am - Reply

      The fertilizer you are using will probably work well for now, You might want to try and find something with a little K, or a K supplement. The plants probably will slow down the vegetative growth and no I would not suggest pinching tops this far into flowering. I think you best bet is to try to bent those branches down as much as you can. Happy to hear you have found our articles useful. We do our best.

  74. uknome October 24, 2012 at 8:12 pm - Reply

    Is the reason u suggest not pinching tops so far into flowering because of losing weight/big bud @top or is it actually harmful/stressful for the plant? Not that I don’t trust ur advice, just curious about the reasoning behind it. Thanx alot. and also if u hav time, I was wondering if it was common in this type of plant, like other tall plants, to use some kind of stick/stabilizer rod stuck into the soil along the stem, or tied to a few inch away for support if it gets too top heavy? Sorry to ask for such detail, I’m just the kinda person who wants to learn all I can about everything. Thanx again

    • Rambo October 24, 2012 at 11:05 pm - Reply

      Happy to help, but since your questions don’t have anything at all to do with the article, could you please ask them in the forum. Thanks.

  75. Lambsheep October 25, 2012 at 1:57 pm - Reply

    I initially started growing my plant on a 12/12 lighting schedule. It has grown to be about 22inches and is starting to bud. Being I gave it no time to vegetate (18:6 ratio) I know it will affect the quantity, but will it affect the quality? In other words, am I still okay?

    • Rambo October 25, 2012 at 2:53 pm - Reply

      Quality should not be effected, just yield. You should be fine

  76. Jason October 29, 2012 at 10:23 pm - Reply

    Hi Rambo. i would just like to know, mixing lights is that a good idea? i have a gro-lux fluorescent light in the attic which gives off red spectrum its 2 40w bulbs as well as a LED which a mate of mine gave to me. i recently purchased a “Crop circle LED lights G73″ will it be pointless in putting it up with the other lights will it prehaps mess with the spectrum of my new LED? your advice will be very much appreciated

    • Rambo October 30, 2012 at 12:52 am - Reply

      Jason- Mixing light is not a problem and is even recommended in many cases. Florescent lights are often used for clones and vegging small plants. I have had great results using the newer high output T5 florescent arrays that run 8 of these bulbs. It should be noted that your “red” 40 watt bulbs are not actually producing only red light, but a mixture that contains more red then normal florescent bulbs I have honestly never used LED lights but the logic behind there use as grow lights is very solid. They reduce energy consumption by producing light in only very specific wavelengths. Because of this they may be able to produce as much useable Red and Blue light with 100 watts as an HPS bulb does with 1000 watts. Additionally HPS and MH lights waist a lot of energy producing heat, a problem that is minimized by LED semiconductors. Another property that LED and Florescent grow lights do not produce is UV light. There is some research that suggest that Trichome production on cannabis plants is a defense response by the plant to UV light. If this is true, you may find the potency of your harvest diminished. From the conversations I have had with several LED grow light makers, they just don’t produce the yield of an HPS or MH light. This may be in part because they are designed to hang above the plant canopy a foot or more and cover an area equivalent to a HPS light. 5 minutes of research into LED’s will inform you that LED lights are directional and that the light diminishes very quickly over distance. A proper LED array would be the same size as the canopy and placed no more then a few inches from the tops of the plants. I expect your yield will pay the price for not employing an HPS light but I would very much like to see your results. Please start a thread in the forum and keep us apprised of your findings.

  77. krisgottiboi November 4, 2012 at 9:36 am - Reply

    hi there i was wondering i have my plant on 11 hrs lights n 13 hrs dark but can i switch to 12hrs on n 12 hrs dark will it effect anything are will it be ok ………..anyone with the answer will help ouyt lots

    • Rambo November 4, 2012 at 12:23 pm - Reply

      An extra hour of light will make the plant grow faster and yield higher. You can probably switch without any problems but there is only one way to find out.

  78. Nick November 8, 2012 at 3:26 pm - Reply

    I recently started to grow,I started from germination and the plant is standing at three inches tall when will i know the sex? Also if its turns out to a male plant what then?

  79. sneaks November 8, 2012 at 9:19 pm - Reply

    hi. i just flipped to 12/12 to start flowering. i have been using a mh bulb. do i need to switch to a hps now or wait til i see signs of flowering. also, should i switch nutes for bloom now as well?

    • Rambo November 9, 2012 at 7:37 am - Reply

      Yes. If you have an HPS bulb then now would be the time to switch to it and start using the higher P-K flowering formula fertilizers.

  80. julian November 24, 2012 at 10:32 pm - Reply

    Question lot’s of them email me

    • Rambo November 25, 2012 at 10:01 am - Reply

      Please post your questions in the forum so that I and the rest of the community can help you. This way others with similar questions can find help there and I don’t have to answer the same questions millions of times. Thanks

  81. Juju214Tx November 24, 2012 at 10:36 pm - Reply

    I have 3 plants planted at different times one of which looks heart the second one looks real droopy the 3rd one looks okay but all of there first set if leaves done dried first time indoor experiment please E-mail me at the address above

    • Rambo November 25, 2012 at 10:03 am - Reply

      It’s not uncommon for the first set of leave to dry up and fall off. This is normal. The plant will discard leaves as it no longer needs them. If you post some pictures in the forum we can help diagnose your plants problems.

  82. lee November 25, 2012 at 2:25 am - Reply

    hi just wonderin if any 1 can help me. our plants have been up 2 week today they lookin good. the light as been on 24hour. wen do we change the time and do we feed them more food?plz get back to me asap.

    • Rambo November 25, 2012 at 10:06 am - Reply

      when to switch from 24 hours of light to a flowering cycle really depends on how large you want the plants to be at harvest. Plants can as much as double in size so a 1 foot tall plant now could be 2 feet tall at harvest. Continue you to feed the plants but switch to a flowering fertilizer higher in P-K after you make the switch to 12/12. Hope that helps.

  83. pdot November 26, 2012 at 6:52 pm - Reply

    do i keep the fan on in the flowering stage

    • Rambo November 26, 2012 at 7:30 pm - Reply

      Yes. Air circulation is even more important while the plants are flowering.

  84. Islanderb December 11, 2012 at 8:58 pm - Reply

    Is it too late to continue veg. state When buds are present. I had power issues and I’ve lost a lot of light time during vegetative state. Buds are now present. Since I’ve fixed the lighting/power issue. Can I continue 18/6 cycle. Since the plants are only 5″ to 8″ tall? Please help. Thank you

    • Rambo December 18, 2012 at 5:02 pm - Reply

      You can try but to be honest the results probably won’t be great. If they are still so small you would be better off either continuing with flowering or starting over.

  85. Magic Dragon December 12, 2012 at 2:33 pm - Reply

    Actually, I have some light filtering in my bud room from cracks in the door. Very little, not more than a 3/4 moon. As cannabis has been flowering in the great outdoors for longer than we have been cultivating indoors, it must have evolved to handle the light from a full moon. Either that or the moon is a relatively new phenomena. I also at times use a green light to access the darkroom. I have never had an issue.

    If just a brief flash can interrupt the plants, what happens in an outdoor garden that occasionally ‘sees’ car headlights?

    • Rambo December 18, 2012 at 5:08 pm - Reply

      As for the moonlight, I suspect that it does not have an effect on flowering because if is not reflecting far red light. I suspect that the light leaking into your grow room will eventually cause flowering or herming problems. Outdoor gardens can be affected by car headlights as well as motion sensor lights often found on outbuildings.

  86. Ricky December 19, 2012 at 5:18 pm - Reply

    Hey im a first time grower also and my 4 plants have started to bud but they are very short , I dont know If I should stay using the 18 hours so they can veg more or if I should just do the whole 36 hours without light then to 12 on 12 off

    • Rambo December 27, 2012 at 9:54 am - Reply

      So you have plants that are flowering under 18 hours of light? This sounds like a strain that may not be reactive to light cycles but flowers based on the age of the plant itself. Was your plant grown from seeds or clones and do you know what strain it is?

  87. Rossta December 24, 2012 at 8:00 pm - Reply

    Do you have any tips for growing in a greenhouse in winter? I am a seasoned grower but this is new for me. I put 25 bubba kush in my greenhouse with two 1000 watt hps. I have been vegging for three weeks and am going to start flowering next week. I plan on flowering for 8 to 10 weeks… Just before Spring starts. I live in a fairly mild client should I buy a heater or is 45to 55 degrees okay at night? Will the increased intensity of sun hurt budding. Any other issues I’ve missed? Growing outdoors at Christmas!

    • Rambo December 27, 2012 at 10:47 am - Reply

      The low night time temperatures may stunt growth but the increased light from your HPS is a good thing, not a bad thing. Heating coils in the soil work great to help keep the roots warm. If your plants are in pots, heating pads will also do the trick. Keep an eye on your humidity when flowering and be on the watch for botrytis and mildew which are more likely in high humidity growing areas. Post some pics if the forum. I would love to see how you have it set up. Happy Holidays.

  88. baileybuds December 28, 2012 at 9:53 pm - Reply

    I have my flower room that is approx 10′x20′ and right now I have 16 plants in flower slpit into two groups, the first group has about 5 weeks of flower time and i have had 2 1000 watt hps digital ballasts with vented hoods over them my second group I just completed a 24 hr dark and started thier first light cycle with the other group. Right now I just have a 600 watt hps digital over the first group. My question is what are the light requirments of plants as they progress through the flower cyle. when do the plants want and need the most light since i only have 2600 watts for the whole sixteen plants i want to knopw how best to get the most out of them. I also have light tracks and right now the 600 is on one over the second batch i just started flower the two thousands i have stationary since they fully light all the first eight with out being moved

    I hope this makes sense to you all
    thanks tons for your help.

    • Rambo December 29, 2012 at 2:40 pm - Reply

      I really don’t know at what point in the flowering cycle the plants need the most light but I would assume that if you are mimicking natural outdoor seasons the plants would normally receive the most light at the beginning of flowering and it would decrease towards harvest when the days grow shorter. That being said, for indoor growing you want them to have as much light as possible the whole time. You did not indicate how big your plants are, but I hope you are not trying to fill you 10×20 room and then use only 2600 watts. Even with movers 2600 watts will only light an area of about 4×12 ft and I would prefer more like 3000 watts for that space.

  89. baileybuds December 31, 2012 at 7:43 pm - Reply

    you are correct on both facts yes 2600 w would be way to small for total grow room space i provided, and i indeed neglected to say that that the two groups take up no more than one third the space(built big in hopes of law changes and also in hopes to grow larger and larger plants that being said my total flower are being used is about 6′ x 10′ } any way through further research I have found that your prior statement to make sense more light to start as nature provides so have repositioned so as first 8 get 1000 on track and second set have 1600 paired so as much more light per ft still would love all sugestions and comments, since i don`t think you can ever know enough when comes to growing pot and brewing spirits
    happy new year all
    again great site

  90. baileybuds December 31, 2012 at 7:49 pm - Reply

    have also recently read that use of a tanning lamp during light and total blue during night at 100 watts per thousand watt grow light will help improve yield and potency have you or any one heard of this and is it worth it, also if worth it how about type and placement should it be close to canapy and tracked or higher so less intensity and more time on plants
    any and all help greatly appreciated

  91. baileybuds December 31, 2012 at 7:52 pm - Reply

    just read post to put in forum area will repost there and look for reasponse there
    thanks for your time

  92. Mahayogi January 31, 2013 at 6:35 am - Reply

    Hey there guys! I asked you a question a few months ago about photo-period interruptions, and now I have another similar question about the same thing.. So I had my flowering tent (located in the same room as my vegging plants) unzipped from the top to about ten inches down, to vent some extra heat. I accidentally fell asleep, and didn’t end up zipping it back up until just under a half an hour after lights out (the veg lights were still going outside the tent). My flowering plants are exactly one month into bloom at the moment… do I need to be concerned about this lapse in vigilance, or will they be fine as long as this does not happen again? I just need some reassurance; I’m sure you understand : ) Thanks – Mahayogi

  93. Rbz008 March 3, 2013 at 10:58 am - Reply

    Gr8 helpful thread rambo. 1quick question. If a outdoor plant grown in winter was bought indoors to gain extra hours of light to stop early flowering, how much light is needed or does it just have to be not dark. Say 1 400w hps light be sufficient to do 12sqm

    • Rambo March 3, 2013 at 9:12 pm - Reply

      In theory the plant being exposed to even a flash of red light should resit the plants systems and stop PFR from turning to PR. In practice, I don’t exactly know how much light is needed. It certainly doesn’t take much. A regular 60 watt incandescent bulb hung over an area about 4ft by 4ft is enough. I suspect your 400 watt would be fine, but consider rotating the plants furthest from the light to the center every few days for more even coverage.

  94. Rbz008 March 3, 2013 at 9:40 pm - Reply

    Thank you very much for replying rambo. 1 more query, my outdoor crop been under rain for weeks now in and lots of leaves are goin yellow, not the normal yellowing. is it possible it could be myrtle rust. Using my mould formula of clove foliage spray and no improvement. I also sprayd catogry1 fungicide+ seaweed b4 this happened. Hope it didn’t weaken the plants defences. Wishi could show u photo. Myrtle rust is locally a problem atm in many commercial crops. Thanx 4your help

  95. Rbz008 March 7, 2013 at 5:08 am - Reply

    Last question Mr rambo. I’ve had my winter crop veging under hps spread spectrum. Will changing to mh for remainder of veg stress them and if not would the results be noticeable. Thanx

    • Rambo March 25, 2013 at 8:32 pm - Reply

      I’ve never tried this but I know a lot of people who switch from MH to HPS when they switch to flower with no ill effects so I am about 99.99% sure you should have no problems unless you strain is retarded.

  96. ivyyt March 7, 2013 at 9:26 pm - Reply

    i had my plants on 12on12of for 20days i was told to set them back to 6off18on wil it hert my plants. my seeds “last minutte” thank you

    • Rambo March 25, 2013 at 8:35 pm - Reply

      If your plants have been on 12/12 for 20 days they should be starting to flower. Changing them to a 18/6 is going to freak them out. They probably won’t go back into full veg for quite some time but they probably won’t flower out right either. Why would you do this? As for “my seeds last minutte” I have no idea what you are talking about.

  97. WillyC April 10, 2013 at 2:36 am - Reply

    I have heard I can use green light to go into the Flowering room. Is this true?

    • Rambo April 17, 2013 at 8:20 pm - Reply

      Yes this is true. However, very few rooms are set up so that you can open and close the door without light getting in.

  98. Borobudz April 17, 2013 at 7:21 pm - Reply

    To make a long story short, I have 2 northen lights autos that are about 7in and 4 weeks old and have been in a 12/12 cycle for 6days because of other plants. Is it too late to go back to veg or just continue with the 12/12 and see what I get? The plants already developed their pistils.

    • Rambo April 17, 2013 at 8:32 pm - Reply

      After 6 days I would probably leave them in Veg. They will probably continue to veg to some degree under the 12/12 lights anyway.

  99. andre April 18, 2013 at 12:56 pm - Reply

    hey noob here…Doing my first indoor grow with a bubble system…Trying white russian atm but im looking to aquire a strand that will produce the fastest…Can I please ask which strain you would recommend and where u recommend getting the seedlings from…It must still be a great herb…thx in advance for any input

  100. Foot Johnson April 26, 2013 at 2:56 pm - Reply

    I just started inducing flowering, switching from 18 hrs of light to only 12. 2 weeks later and not very much has changed. i dont notice any buds starting to form. did i induce flowering too early?

    • Rambo May 1, 2013 at 11:00 pm - Reply

      Give it another week, the plants will flower even if it is to early. Some strains take longer than others. It’s also possible you have an auto flowering strain that does not flower based on light cycles. In that case it will flower when it is ready regardless of hours of light. Uncommon, but possibly if you started from seed. Impossible if you started from clone.

  101. nunya May 1, 2013 at 3:27 am - Reply

    is this post still being monitored? i have some crucial questions about starting indoor with some artificial light(flourescent) and then moving to outdoor


    • Rambo May 1, 2013 at 10:53 pm - Reply

      Yes, Sorry for the delay, We get a lot of questions on here and unfortunately I have a million other things to do since this site produces nearly zero income and the bills don’t pay themselves. I might point out that while everyone seems to be using this as a place for questions and answers, the comments section of a blog post are meant for comments. While I don’t mind answering questions the forum is really the better place for it. That way others can post answers as well.

  102. Harry May 6, 2013 at 8:44 am - Reply

    Thanks Rambo for a very informative site. Been growing many years outdoors in nor cal sierra nevadas, 3500′ elev. This year, I started a little earlier than normal, got good clones from Harborside, went outside into a greenhouse. Yep, you guessed it, I’ve got a lot of plants showing flowers. The blue dreams and amnesias are OK, but others not so much. After reading your info, I should have had a light on for a couple of hours in the evenings in my greenhouse. I will start tonight! How many hours do you think I should add now to reverse flowering back to veg, and would flourescent be better than incandescent, or does it matter that much. Thanks so much!

    • Rambo May 7, 2013 at 11:25 pm - Reply

      Since you are trying to draw them out of flowering and back into veg, I would probably give them 24 hours of light until about June if possible. Fluorescent or incandescent both work floros are probably less expensive but make sure you are using ones that emit some red light.

  103. inandout May 11, 2013 at 10:26 am - Reply

    Need some advise from someone urgently!!!!!

    i’ve got 10 nice ones going. they’re original skunk started from seed but i have a bit of an urgent dilemna.

    they’re about 16-20 inches tall. i have been keeping them on 18/6 with flourescents, obviously indoors. I put them outside during daylight hours to get sun.

    but now i have to sex them and reduce the number down to 2 or 3 for the sake of space. what is the best way to do that? keep using artificial light and reduce to 16/8 maybe?

    or can i stop flourescent altogether, and put them outside and go with normal daylight hours? nights are mild and right now a day lasts 14 hours here. so if i put them outside the days will be getting longer for another 5 weeks, and maybe they won’t show their sex.

    thanks in advance for quick reply. if somethings not clear let me know!

  104. Janis May 18, 2013 at 8:08 am - Reply

    I’ve heard that once you switch to 12/12 that the plant needs to have 12 hours of uninterrupted darkness and that even a crack of light can throw them off flowering. Is this just because they are indoors or are we to assume moonlight doesn’t affect the flowering process when growing outdoors? Or is moonlight just different from a standard house light?

    • Rambo May 22, 2013 at 11:38 pm - Reply

      This is a good question. Moonlight is reflected sunlight so the color spectrum should be about the same as sunlight. This means it should produce far red light which should change PR to FPR telling plants not to flower. I suspect that there is so little far red light reflected that it has a negligible effect on the plant. This would be a good questions for a botanist.

  105. prickles May 19, 2013 at 5:37 pm - Reply

    my timer screwed up and gave my week 7 flowering plants an additional 9 hours of dark before i discovered this and turned them on.
    i have gone back to the regular cycle and am assuming that this minor hiccup will do no harm!
    your opinion?
    regards, prickles

    • Rambo May 22, 2013 at 11:28 pm - Reply

      I think you’ll be just fine.

  106. AKA moneyman May 23, 2013 at 7:52 am - Reply

    when you start the seeds what is the light cycle and how long be for you change to 12/12 cycle.This is my first time growing indoors and outdoors

  107. Dan Murphy June 6, 2013 at 5:21 pm - Reply

    If my clones do start flowering early, is there any way to return them to vegetative state?

    • Rambo June 10, 2013 at 10:48 am - Reply

      24 hours of light and a prayer

  108. jimi June 10, 2013 at 7:56 pm - Reply

    skunk #1 how long do i need to veg before switching to 12 12 i grew back in the early 80s for 3 or 4 years and grew northern lights and nl#5x haze with great results in dirt and some in a ebb & flood in rockwool also. back then the genral consenses was 2 months veg and flower till finished now a days i see claims of much lower veg times im using deep water culture and im impressed after only 10 days i have alot of really healthy roots and incredibly fast growing plants from seed so i need to sex them but my goal is to cut 10 to 20 clones per plant but at this growth rate 2 months of veg im going to run out of space height and width i started with 10 skunk #1 seeds regular i want one male to grow my own seeds in case i need to start over and then start with all clones main question will 1 month of veg be enough for the plant to mature enough to start flowering with this strain. i have always been under the impression that when starting from seed 2 months of veg was manditory thank you

    • Rambo June 17, 2013 at 11:24 am - Reply

      This involved questions requires an involved answer and probably some discussion. Please post it again in the forum.

  109. Tewks June 24, 2013 at 4:14 pm - Reply

    i love your web sit,let me get to it” I am a first time grower and i started out with 50 plants… not sure what kind ? they look great. But I started putting them in darkness for the 12 /12. But it seems like every 3 to 4 days i get a male or 2.” Should i be worred? Or is this commen??

    • kram July 7, 2013 at 11:21 am - Reply

      I suggest asking this question in the forum where moderators can help you.

  110. Gary Rose July 25, 2013 at 11:53 am - Reply

    Can u have 18 hours of darkness n 6 hours light in budding stage

    • Rambo July 31, 2013 at 7:25 pm - Reply

      Sure, but why would you want to do this? The plants need light and with only 6 hours your plants won’t reach their full potential.

  111. buddie July 30, 2013 at 11:23 am - Reply

    Plants currently in 12/12 from 7 pm to 7 am. Because of job, need to change photoperiod from 9 pm to 9 am. What is the best way to transition, or will I lose my plants? (Plants in various stages of flower, one new plant each week).

    • Rambo July 31, 2013 at 7:19 pm - Reply

      Just make the change. You don’t need to do anything special. The plants will be fine.

  112. Jennifer August 3, 2013 at 6:11 am - Reply

    After the 36 hours do i go back to light for 12 hours? Then dark for 12 hrs??

  113. cmsierra September 3, 2013 at 9:41 pm - Reply

    Question, in a hydro grow, we were vegging under a 400 light until we get ready to switch them into a different room. The new room has a 1000 light. We lost 4 plants the first time and thought it was due to improper rinsed coolers but this new round is starting to look the same yellow wilting leaves. Is it possible taking them one light to the other is causing this “shock”. Our first 2 grows we vegged under the 1000 and then bloomed under the 1000. the first crop was okay but the second was amazing. Just wondering if you have known of other indoor growers having this issue. The strain in Thai OG and the room is temp and moisture controlled.

    • Rambo October 2, 2013 at 9:20 pm - Reply

      Sounds like some kind of shock. you could ease into the new room by raising the lights as high as possible for the first few days.

  114. planebill2453 September 8, 2013 at 9:22 am - Reply

    Best Forum I’ve seen!!!
    I’m growing two plants outdoors since April, in NJ. They are 3-4′ high and starting to bud. They get a lot of light and it seems we are on a 12/12 cycle now naturally. How can I increase bud production and growth? I have about 4 weeks till first frost, and would like agood harvest. I’m a chronic pain type from serious accident, so its important to me.
    Also, is it safe to buy seeds online? Thanks a bunch.

  115. sperk October 25, 2013 at 5:39 am - Reply

    Hey. This is my 1st grow(hydro). Im confused alittle bit on a few things. Im using, rockwool cubes and ph is perfect. I know pretty much about he ligehting from. recnt comments. After how many weeks do i change from18-6 to 12-12 the strain is indica and do i changr lighting again?. Also have nutrients do not have a clue wjat to do and how much 2 put in? I have root juice bio bloom and bio blossom can someone help out on wich weeks to do. and how much if any? 600w pellets and soil, do i use just pellets or soil and pellets? Hope to heer asap cheers!

    • Rambo October 29, 2013 at 7:01 pm - Reply

      We would love to help you out but this is pretty involved so please take your questions to the forum. Thank you.

  116. Steph November 13, 2013 at 11:21 am - Reply

    Hi, all this information has been so helpful so far. My plant is 5 weeks after first appearance and she is on 24/0 cycle. Im going to start flowering her now and was wondering should i move her straight to the 12/12 or try 18/6 for the first week? she’s about 22″ now and gorgeous bright green. She’s white widow.

    • Rambo November 19, 2013 at 5:46 pm - Reply

      straight to 12/12

  117. Taylor fArms December 3, 2013 at 1:53 am - Reply

    hey there. I i have a quick question on the subject of artificial light for flowering. have you ever encountered a problem with the 13 hour light cycle on, causing an overload of Prf that the plant cannot convert within thee 11 hours of night? i have read another article of yours on sativa strains needing more darkness than light. i believe my hybrid strain is sativa dominant. if you can help me at all it would be appreciated. i don’t have any of these to experiment with or i would. any tell tell signs of over lighting that you know of would be a great help. im going to revedge a few to try it my self but you could help prevent some loss my way.

    anything would be appreciated

  118. martin December 17, 2013 at 2:31 pm - Reply

    Hey so my friends got a nice cycle goin BUT he over did it on the dark cycle during seed formation anyone know if that’s bad???are the seeds still viable

  119. brett December 31, 2013 at 1:26 am - Reply

    Just woundering first tym grower,Can i cover my plants in complete darkness to make them flower early if growing out doors.Just woundering as I know u can do this in doors but using 12/12 after ? cheers

  120. Average Joe January 6, 2014 at 1:31 pm - Reply

    Im using small 20 watt xenon bulbs and my plant flowered without a change in the light cycle (16/8)
    I looked into it and the light in the red and far red is very low with xenon.
    Do you think I could just leave the lights on for a straight 24 hours during my budding since the chance of production of pfr is very low?

  121. Sparky January 14, 2014 at 8:43 am - Reply

    I’m a bit paranoid about my smart meter and considered flowering with a photosensitive switch, the kind that turn on at dusk and off at dawn. This would conceal my electrical consumption to look as though I have a 300W safety light outside.

    My concern is that as I induce flowering at this current date in January, I’d have longer periods of day light. There would always be at least 12 hours of dark but it would gradually be increasing, probably from 13/11 to 12/12 by harvest.

    Any ideas what this might do to my plants?

  122. February 2, 2014 at 10:38 am - Reply

    I am sure this piece of writing has touched all the internet visitors, its really really fastidious article on building up new web site.

  123. Dominik February 12, 2014 at 10:21 pm - Reply

    Is it true that urine helps bud production? I’m worried that my neighbors are going to catch me on my balcony with my pants down, so to speak. I did have enough sense to add my manure to the soil inside where they can’t see me but the plants are too large now to easily bring them in for urination.

  124. mikehay March 14, 2014 at 11:37 am - Reply

    I just want to thank Rambo I am a newer grower and your spot on my harvest was great thanks to your advice

  125. Dan March 15, 2014 at 3:33 am - Reply

    Ive got 4 babys right now under flourecent lights and ive had umm for about a week and there growing but there not producing any more leaves theres still only 4 and the leaves arnt getting any bigger. can someone tell me if this is normal and if not what should i do.

  126. Cris March 24, 2014 at 11:43 am - Reply

    How do I know what strain I have?

  127. Pineapple x Buddha April 2, 2014 at 9:08 pm - Reply

    You got a lot of things wrong and a lot of things right. I am developing new ways of cultivation. The end results are fabulous. Never ever bud a plant when it is only 20″ tall. You are robbing it of its glory. Go big or go home. Graft vigorous root stock on your clones and put them in no less than 30 gallon pots. Let them get big. Then pop then into veg. Also prune your shit constantly. If you wanna enter your grow during the dark period use a dim head lamp, it will not affect a thing. Go completely organic as well. When they start to develope buds girdle the main stem. Never used LED lighting and use 1000 watts per plant.

  128. Deborah April 9, 2014 at 12:02 am - Reply

    Hi, new grower with quick question. My girls got started on there flowering accidentally on a day 12/12 schedule , now. My room gets way to hot, so is it going to hurt them if I leave there lights off long enough to put them on a light at night schedule ? Like 19 hours not 12 ? Just to switch them to on at night time, so just a one time trauma. I’ve been stressing trying to find out what is right, so I don’t hurt them in any way.
    Thank you so much !

  129. Pete May 3, 2014 at 10:33 pm - Reply

    For the first time, this season I obtained small rooted cuttings about 2 weeks ago. I put them into 3 gallon bags and onto an 18/6 light cycle. They will be transferred into 100 gallon grow bags outdoors to then carry on with just natural light until harvest. In previous seasons I obtained quite large plants which were put into the outdoor grow bags towards the end of May, blissfully unaware of how these plants had been grown, or of anything to do with the plant response to day length, and had quite good results with yields of up to 4 1/2 lbs per plant. My clones this year are rapidly outgrowing their current home with the 18 hours of light, and although I’m not wanting to transfer them outdoors quite yet, the natural light where I am (39.11N) is never even close to 18 hours and I certainly don’t want these plants to go straight into flowering mode when I put them out, with the significant reduction in light that will mean. Should I start now gradually reducing the light from the current 18 hours, or what do I need to do to ensure uninterrupted vegetative growth continues until the plants know that the natural autumn has arrived?

  130. bob May 5, 2014 at 9:00 pm - Reply

    how often should I water when flowering

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  135. Higgins July 2, 2014 at 6:38 am - Reply

    New grower here! I found a see in one of my bags so I planted it and it is two weeks old today and looking bright green about 3 inches tall. When will I be able to tell if it is male or female? how much longer? or will it need to go into flowing before I can tell?

  136. Gmac July 8, 2014 at 2:58 am - Reply

    I have already started my 12-12 cycle, going on day 5
    then i read about the 24 or 36 hr lights out
    can i still do it ? or is it to late ?
    new grower and wanting to learn it the right way, the first time
    plants are 32″ tall and hella healthy
    7x5x8 room under a 600 watt air cooled light
    would love some thoughts on this

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  138. brucie86 July 16, 2014 at 6:31 pm - Reply

    I have a question I have 2 growing beautiful I just switched them to the 12/12 cycle an I was readin
    And it says to leave in dark for 36 hours now it wont hurt them being in the dark for 36 hrs n do I water them during the 36 hr dark cycle

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