I read somewhere that it is the dark of 12 hours that dictates, or that it registers, for flowing. So it does not matter how much light time…12-16-18-24??? as long as the night time that follows is 12 hours uninterrupted. This sounds strange to me, but interesting. How would a plant respond if it had even just 4 hours more light between dark periods? Bigger for same amount of growing days?
If this is true, how many hours of light would be too many before the plant stressed?
Anyone ever heard of this, or tried playing with the hours in this way? Thoughts?
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I’ve often wondered this same thing
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But you know, I think of plants kinda like people. I can work 12 hours days, sometimes longer. But man, when your head hits the pillow…
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Dont you just love it when you go I to work and relieve the same guy that comes back in 12 hours to relieve you. Gotta love that overtime check though
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I don’t understand your question… 
I am a stoner tho… 
He is asking how a marijuana plant would do with a light cycle of 24/12. Since the plant is still getting a full 12 hour dark period.
Or up to that, 16/12, 18/12,…just more than 12/12. Hopefully we will get some input here.
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Gotcha…
You can candle stick the plant…
If it gets 12 hours of darkness , it’s going to flower or at least send out the hormones to flower and if you start adding 24 on and 12 off and 24 on and 12 off and so on…
I’m not sure what would happen , … pretty sure its gonna do something crazy…
Sounds like a good experiment for you to try…
Let me know what happens… 
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Hey guys interesting questions, i read somewhere, don’t remember atm, that the buds grow and swell during light off, they don’t grow during the daytime, daytime is used for photosynthesis, so adding an extra 12hrs shift to photosynthesis cycle, would actually rob you of growing time, at night, for example 12 night then 24 day, then 12night again 24 day, at 2 cycle at that rate, your only getting 24hrs of growing, compared to if they were left at 12/12 you would all ready have 48hrs of night time growth. Catch my drift, were all perrty medicated, hopes this makes sense.
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That is a good point. I wonder though, if maybe a 16/12 or something like that would be just enough to kick up the growth? Kinda like giving them the benefit of the autoflower by a longer light schedule, but since it is a photo is grows way more than the auto.
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Im not 100 percent sure but i could be wrong but a member posted a thread on buds growing at night, just dont remember who, it was a very interesting topic, also explained about the farred light and effects it had on flowering stage of our beloved mary, if i find it I’ll tag you my friend @Tr33
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Definitely an interesting experiment. Would think with a 24/12 it would be in a constant limbo of flower and reveg. May end up with a very odd looking, round leaved plant. 14/12, 16/12 would be where I’d test.
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All great points, i agree with everyone else it would be a great experiment,
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i would advise against this honestly… i have seen light chages and inconsistencies do crazy things including set off a hermie farm and noone wants that… auto’s should even be kept on a stable light cycle based off of a 24 hour clock… once you start running 12/12 cycle you shoulnt go longer than 12 ON again unless you are re-vegging…
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Life on Earth has developed under 24 hour long days. The photoperiod is counted as 24 hours. Technically, if you do 24 on and 12 off, the plant will only get 2 dark periods every 3 days.
Was hoping the original poster would try it…
I’ve been waiting for the results…lol
12 hours of darkness or Anything longer than that will cause the plant to want to flower…
It has to do with hormones and such in the plant…
I’m still interested to see what would happen…
I’m pretty sure that the plant would go bonkers…
I would only try this with a reg seed that was female… 
You would be less likely to run into something weird with true reg , fem , seeds…
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Well After getting everyone settled in our tent and gettting thetemps,lights and airflow setup finally. our girls were like stuck in a pre-flower mode. I had to prune/trim/deflower a bunch of lower fan leaves and other leaves that were useless. I follow the wet/dry watering and fed them once or twice and week. Well I was surpiried last nigt @0130 I went down and checked on them and both had grown. 4" in a 24 hours and are now showing those white pistols. I couldn’t believe it’s like they both woke up after a long nap… Theyboth drink up a gallon of water each with almost no runoff. BTW I run lights 19/6 -20/4 due to the lights not being strong enough. VS1000 LED vivosun light I added a Burpee two bulb fluorescence grow light set.