Basically: Flower Light Cycle is 12 hours on and 12 hours off and the Veg Light Stage is 18 hours on and 6 hours off.
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.
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.
Your plants will start reverting back to the veg cycle.
You will see single leaves starting to grow out of the buds – that’s normal –
After 10 days, change the 24 hours on back to the vegetative lighting schedule you use, we use GLR
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.
Since feminized seeds can be cloned, they are the way to go. All you have to do is plant the seed and you’re growing females.
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.
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.
Now we have to switch back to the vegetative stage
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.