How To Change The Flowering Cycle Back To The Vegetative Stage or Cycle. Basically: Flower Light Cycle is 12 hours on and 12 hours off and the Veg Light Cycle is 18 hours on and 6 hours off.


  1. I have reverted plants that were in the flower cycle for up to 3 weeks back to the veg cycle with no problems other than losing time.
  2. All you have to do is change your flowering light cycle of 12 hours on and 12 hours off to 24 hours on for about 10 days.
  3. Your plants will start reverting back to the veg cycle.
  4. You will see single leaves starting to grow out of the buds – that’s normal –
  5. After 10 days, change the 24 hours on back to the vegetative lighting schedule you use, we use GLR
  6. Be very strict during the off hours – allow no light to come in – don’t open the door – be patient!

A time consuming task but one that has to be done, is figuring out the males from the females when you’re growing from regular seed. We’ve been growing weed for over 40 years and still can’t tell a female from a male until they flower for a week or two.


IMO-growing from regular seed is better than using feminized or auto flowering seeds. Regular seed will give you a larger, more robust plant that you can easily clone. Check out this link to find out where I get my marijuana seeds.

Many growers can tell, or at least claim they can spot a girl from a boy and there are many articles and videos about it, but we can’t figure it out. So we’re stuck; when we grow from seed, we have to allow seedlings to grow for awhile in the vegetative cycle than start flowering them (switch from 18 hours of light to 12 hours of light) so we can figure out who’s who. ir?t=growingweedindoors 20&l=li2&o=1&a=B01IW8M31U


After you switch your lighting schedule to 12/12; to tell a male from a female, look for little balls (male plants) that start to form and get rid of those plants, (we do save one to pollinate 1 female for seeds).  Sometimes the little balls start forming in a couple of days and sometimes it takes a week or two.

Female and male marijuana plants




Now we have to switch back to the vegetative cycle


Once we have our girls (they have white wispy hairs/no little balls) figured out, we change the flowering light cycle back to the vegetative cycle. We start with 24 hours light for about 10 days then switch to the GLR.


You’ll notice weird looking single leafs growing up through the little buds. Don’t worry about them, just pick them off if they make you nervous or leave them.


After 10 days of 24 on, we change back to our normal veg lighting schedule, we use the GLR (Gas Light Routine) for the remaining time in the veg cycle (now you can see why clones are so much better to start with).


Even though the plants initially look a little weird, they grow out into normal looking plants in a short while. Once you have a group of female plants growing in the vegetative cycle, you can start taking clones when the lower branches get to be around 3″ long or so.


All in all it can take around 3 weeks to differentiate the boys from the girls so it makes a lot of sense to keep a mother plant growing so you can take female clones anytime you need them.




These are the products I use to grow the best weed


    33 replies to "How To Change The Flowering Cycle Back To The Vegetative Stage or Cycle"

    • steve

      Hi Gs
      Ive cloned rooted and waited 6/8 weeks to revert some ladies taken right to the end. Worth the wait. Use 24 hrs and low nutes. Plants with big roots and little above the soil WILL burn very easily. 1/4 strength and raise N only when its mutating back… pull all these curly leaves off when new 3/5/7…. comes on. I have also reverted whole 2 plant crop… did not bother cloning…waiting….so I thought?

    • Rachel

      It’s BlackBerry Kush. So far it’s on day 3 right now with constant light.

    • Rachel


      So I have Been growing a plant inside since November and I’m use to normally growing outdoors in the summer and end up with massive plants and a lot of bud on it. This one though is starting to flower and I want To revert it back to veg since it’s not the size I’d like it to be yet and won’t produce a lot of bud at the size it’s at. So your saying I have to keep my grow lights on for 24 hours for 10 days straight to get it to stop flowering, then go back to my normal hours?

      • press

        Hi Rachel,

        Thanks for visiting my website.
        It depends on strain but yes, about 10 days.
        You’ll know your plants are reverting when small single leaves start growing through the buds.

        • Rachel

          Can I email You with photos? Iv never had this happen before so want to make sure it’s working what I’m doing! It looks like single leaves are coming through the middle of the pistils.

    • press

      Hi Tyrone,

      I’m sorry I missed your question. For some reason I didn’t get the notification.

      To answer your question 3 months late;

      Caution, since you’re giving your plants 24 hours of light now, they will flower if you move them outside because of the light time differential.

      I suggest you change your lights indoors on a gradual basis before taking the plants outside. I can’t really say how long but I know this, everything with marijuana happens slow so you have to be patient.

      I might go to a veg light schedule something like this to help the plants stay in the veg cycle when they are moved outside but it’s really hard to say for sure: 23, 22, 21, 21 20, 20 19, 19,18,18, 17,17

      The best way to grow outside is starting your plants outside and let nature run it’s course. Moving from inside to outside can be a gamble.

      I apologize again for the late response. If I don’t answer right away, hit me up at: vince@growingweedindoors,org


    • Tyrone Hayward

      Hi all
      I have 2 clones which were given to me in flower, i have since reverted them back to veg state. These are in buckets which are outside during the day then brought inside at night which i keep on the light for them. Now that they are in veg state, can i just leave them outside permanently with a natural light cycle?? Im in New Zealand & we have daylight savings at the moment, which means we basically have daylight from 6am till 8.30pm. Any pointers is greatly appreciated

    • JIMBim

      Cloning is faster for the continued growth of the mother plant and re-veg is faster to find sex. Re-veg is 10 days onwards. Clone is at least 14 days . But the extra time the mother plant gets under the lights means clone plants is likely bigger.
      Bonus for cloning – the clone can be used as test smokes wayyyy before the mother plant is done growing.

      So I’d trade learning the sex of a plant for 4-7 days if I get a taste weeks earlier.

      • press

        I agree, cloning is the way to go.

        Word of caution cloning plants from mothers grow from feminized seed: IMO, clones from fem plants are not the best plants, prone to insects and mold and will get really leafy.

    • Michelle

      Hey hey 🙂 so i recently moved … and found a cannabis plant in the shade . We are now currently in winter. I am not sure of what strain it might be… but its definitly weird looking… leaves are different.
      I was just wondering if its possible to switch it back to veg as it already started flowering ….

      • press

        Hi Michelle,

        Thanks for stopping by.

        I’m guessing the plant you found in the shade is reverting already.
        When they revert they grow weird looking single leaves out of the buds.
        Those don’t hurt anything and you can pick them off if they bother you or just let them grow out.
        You can grow her in the veg cycle and she should grow okay but there is a small chance she may herm from reversion stress but it’s still worth it.

        Sorry for the late reply.

        I just harvested 19 plants and I’m tripping on weed laying around all over the place.
        Usually I answer ASAP.

        I’m doing something new: I saved all the trim (I usually just toss it) and I’ll be making bubble hash with a new machine I got for Father’s Day.
        I did a test run two weeks ago and it really works and the hash is a great change of pace.
        I’ll post something about it when I do so subscribe to my blog and you’ll be notified anytime I post new stuff.

        Take care,

        • Michelle

          May i contact you on email please . Ill send you a few photos . Cause the way the leaves are is just weird . Lol . It doesnt even look like a cannabis plant but the smell says it all

    • Adam

      How soon can I put my plants into flower to get sex signs.? my plants are about 4/5 weeks old And I want to get signs as soon as possible and revert the females back to veg

      • press

        You can do it right now. Change your lights to 12-12 and you’ll see the change usually within 10 days. I usually see the pollen sacs first. Sometimes in just a few days.


      I have smaller plants veg with my mature plants, & now its time to flower. What should I do with my smaller plants? I only have one 4×2 grow tent.

      • press

        Keep the smaller plants out of the tent using their own lights in the veg cycle. When the older plants are done, move the smaller ones into the tent. Or you’ll have to flower them with the mature plants. Won’t get much but it’s better than nothing.

    • joshua

      accidentley went into flower early reverting back to vegetation. put into 24hr light for 10 days and have had 20/4 light cycle for 5 days I have little bud node sites and wondering if I should pull them off. I believe theyre reverting back to growing leaves out of them just not 100% sure.

      • press

        Josh, if you can email me a photo of one of your plants I’d like to take a look.

        I answered on chat but I’d thought I answer here too in case anyone ever runs into this.

        Leaves should be just starting or will start any day to grow out of the little buds.

        You have to be patient when reverting your plants because not much happens while they’re are doing it and reverting does add time to your grow.

        One thing I should mention is that I’ve never reverted a plant started from a feminized seed before.
        I’ve only reverted plants grown from regular seeds.

        Plants grown from feminized seeds can be a bit more challenging to grow because they stress easily. You’ll see the stress in weird coloration’s in some of the leaves.
        If they get overly stressed they will herm so have a rigid following of the light schedule you’re using and be careful when watering and when applying nutrients, less is better than more when it.

        One other thing I’ll mention Josh is make sure your plant isn’t herming or turning into a hermaphrodite (male and a female characteristics).
        If you see little balls (pollen sacs) starting to form the plant was stressed to the point of herming and sadly that plant would be for the most part useless.

        Thanks for stopping,

    • Jayme M

      Great article.
      Do you have to give them 24 hours of the first 10 days or can I do 18 hours ?

      • press

        Hi Jayme,

        Thanks for stopping by.

        Every time I’ve reverted a plant I’ve put them under 24 hours of light.
        The first time I did it because it made sense to me and I’ve done it a ton of times since all successfully.
        I haven’t tried 18 hours but in all reality it should be okay because it’s the normal VEG hours.

        If you want 18 hours to save a few bucks on your energy cost I advise to bite the bullet and run 24 hours because I think they revert a bit faster.
        If you want 18 hours because it’s more practical for your situation then by all means it should be okay.

        Thanks again for stopping, I’m always around.

      • press

        Hey thanks by the way!!!

      • The noob

        18hr on 6hr off or 24 on and ? Off, I just want the perfect info for reverting a flowering plant come on guys , your not Being precise you know there is retarded people out there listening to you guys

        Me , the noob who grows in freakin tents

    • Gary Edward White

      no matter what timing I use I have pre-flowered every grow. Some revert some die, they’re all screwed up. None of the suggestions have helped me. (outdoor) I don’t use any artificial light, I start the first day of spring with Fem. seeds and they pre-flower every year. Can’t stop it.

      • press

        Hi Gary,

        Thanks for the comment.

        When growing outside, Mother Nature takes care of flowering. There isn’t any timing unless you’re doing something like moving the plants in and out of the sunlight yourself.

        For example, where I live in the mid west, when I start a plant outside at the end of May, it will grow in the veg cycle until about the middle of July then the plant starts to flower because it detects the change in light; the days start getting shorter. Then it grows in the flowering cycle until harvest.

        You said your plants pre-flower every year; what do you mean?

        When you plant your seeds in the spring, they shouldn’t start flowering until around the middle of July.

        Are you using auto-flowering seeds by any chance?


    • Tim

      Why don’t you just take a clone from each plant during veg and flip the light cycle on the clone? Ta da, you just sexed each mature plant.

      • press

        Hi Tim,

        Thanks for the comment.
        Absolutely, you can.
        Great idea!!!

        I’m too lazy.
        Do the math; time wise which works faster?

    • Jeff Parker

      I read your article. Thanks for sharing informative content. I really like your excellent content.

    • kevinjoseph

      Thanks for the article; I really like this post it was excellent and integrating post. The period of growth between germination and flowering is known as the vegetative phase of plant development. During the vegetative phase, plants are busy carrying out photosynthesis and accumulating resources that will be needed for flowering and reproduction.

    • Sam Evans

      i took my plants indoors due to the wet weather we have. bud rot is huge in mass.. i put into a room and lights are on a schudule to run at night to save cost. question: will a 24 hour, 1 day light change be a bad thing during the flowering last stage…

      • press

        Hi Sam,

        Thanks for stopping by.

        If I understand, you brought plants inside that are presently flowering into a room with existing 24 hour light and you are going to take them back outside in one day.

        How close are they to harvest? If they’re outside plants, you should be pretty close right now.

        If you only have a week or two until harvest, one day shouldn’t hurt.

        If you have longer to go, 3-4 weeks or longer, especially if they are grown from auto-flower or feminized seed, I wouldn’t mess around, keep them dark tonight somehow as they are super sensitive to everything and will start to morph in a blink of an eye. Morphing is not good.

        Thanks again for stopping, I hope I was helpful.
        I’m here tonight if you need me (watching and hoping the Yankees lose). LOL


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