So I think we can all agree that for most strains we want around 12 hours of darkness per cycle to initiate and maintain flowering. What I’m wondering is can each cycle have 12 hours of darkness but be accompanied by more than 12 hours of light. Basically, does the 12 hour dark period have to occur every 24 hours. Could it be 13/12, 14/12, 18/12? I realize that without a par meter and dli calculations this might be pointless but it’s just a curiosity at this point, not something I plan on messing with tomorrow.
Depending on the species I know some flower closer to 14/10 or 13/11 but it’s a bit of gamble to Try to push past what is natural since thats kinda what we’re doing is stimulating nature
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I’m not so sure we have to stay locked into a 24 hour schedule. I have heard some require 13 or 14 hours of darkness to do their thing. But same logic would apply right? Could you run 16 light 14 dark. 20 light, 14 dark?
Not really. There’s only 24 hrs in a day and their circadian rhythm’s are tuned to that.
I’d think it would cause hermie’s by extending their days to 30 or 34 hrs and / or messing with the light cycles too much.
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It depends on the intensity of your lights!
You could run 6 on 6 off if your lights gave the plants enough energy to do so!
But to answer the question here as stated NO DONT MESS QITH THE LIGHT SCHEDULE IF YOU DONT HAVE ANY ISSUES WITH YOUR PLANTS/FLOWERS
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@Oldguy the days are long enough I’d hate to stretch them out further.
Let’s shorten them to 8 hour days instead
4 on 4 off , turn one day into 3 
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Do you think they are tuned to that innately or because that’s what we all accept as a “day” and run our timers as such. My thought was the build up of something (I forget) throughout the dark period signals to continue flowering. My curiosity is how often that buildup is required to continue flowering. Or maybe I need to read up on it again. Has been a couple months lol.
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So what you’ll have is
Plant sucks in light and co2 and churn that into glucose
Over time it exhaust itself being able to do this and needs to expel the built up energy and needs dark periods to do so
During the dark period it uses the energy to build itself and its flowers using this energy and expel any gases that may be built up.
If we don’t balance both we all suffer
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I have seen the argument made that plants don’t require any dark at all for healthy growth. But I’m with you in my playing around I have found that a dark period of some sort is beneficial. But if 18-6 is fine for veg. Why couldn’t 18-12 work in flower. Or 14-12 if you want to be less extreme. If you get the required build up of “florigen” according to some article I just read in the 12 hours. Wouldn’t they continue to flower regardless of the duration of the light period (within reason of course). I’m just thinking out loud here and wondering if anyone has played around with it. Not something I plan on doing to my girls lol
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If you’d like to extend your flowering time by 10-20% go for it
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Remember plants will stop creating energy also, so by adding time to your cycle it’s basically wasted time
I’ve never meet anyone who made an argument to extend the days tho. More people would like to shorten their days or turn them into two 24 hrs/2 (6on/ 6 off / 6 on 6 off)
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If I can hit my DLI for 12hrs there’s no reason to extend the day.
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Agreed. But realistically how many people are doing that? I’m new to this, I have no idea if I am or not.
I’m not sure that all the counterpoints already stated are supported by empirical data. They may be correct, but I’m not sure there’s been much formal research. The hormones that signal flowering are regulated by photosensitive proteins in some cannabis cultivars. Even when we exclude scotoperiod-insensitive cultivars (autoflowering plants) from the discussion, there seems to be quite a bit of variation in the day-length sensitivity of the species as a whole. So now I’m curious.
The big challenge is actually more practical; Off-the-shelf light controllers are based on a 24hr day-length. It’s entirely possible to automate using arduino or Google home automation products (or similar), but it’s not as straight-forward as our typical light timer.
I do strongly agree with the overall sentiment expressed by @PharmerBob and I would not mess with conventional light cycles without good reason. 11/13 or 12/12 for flowering, and somewhere between 16/8 and 20/4 for vegetative growth are proven to work, as far as scotoperiod cannabis is concerned.
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Exactly. Use enough light!
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I only run 12/12 from start to finish. I will not change it at all. It works perfectly for me. Plus if I did run a 18/6 then 12/12 the plant would take up 100 sq feet by itself. 
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@PharmerBob You know it. Wait to I unveil what seeds I am dropping tonight. This grow I am going to try and stay on top of it. Because I am dropping 6 seeds tonight. This year I planned to have colder temps in hopes for color change.
My point was if you have good lights, you really don’t need more than 12 hours of light. One thing I am finding thst Autos grown on a 12/12 start to finish they just don’t produce as much. Hopefully its just the Auto lating down aeeious roots.
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