How many hours of dark are TRULY needed to induce flowering?

Of course "we all know" cannabis "needs" at least 12 hours of dark to induce flowering, but how true is this?
Could a plant enter flowering with just, say, 11 hours of darkness? or 10 hours of darkness?

If 11 hours of darkness were to be enough, wouldn't it be beneficial for even bigger heavier buds considering the extra hour of light plants would be receiving each day instead of regular 12-12?

Tell me what you think or what you know

Strain dependant. Some will at like 14. 12 is just a good rull of thumb. Also the more mature the plant is the easier and quicker it will produce it's flower hormones. A plant that was vegged for 10 weeks will likely flower with less extreme of a photo change. It's just so eager to produce those hormones

Try it and see, the downside might be less dense or airy buds, but you’ll never know unless you try. That said, I’m sure it’s been tried, and if it worked, you’d think it would be the standard.

Rememeber watching a time-lapse video on youtube was only cut the hours back to 12 12 you did see the plants waking up after 6 hours and then going back to sleep again

No more than 14, tried and tested outdoor, indoor, whatever.
The major issue is their sensitivity to it, even at 13-14 hours the plant can decide to reveg all of a sudden...
So like said above, 12 is a good rule of thumb, anything above is the exception.

Most strains flower at 14.5/9.5.. I've done it, wouldn't recommend it tho.. Very larfy bud..

When I grew outdoor, my buds would start flowering around this week, or the first week in August. I just googled “daylight time for today” and it says 14 hours 43 minutes for my area. We’ve been losing daylight, so that seems to line up.

MissinThe90’sStrains said:

When I grew outdoor, my buds would start flowering around this week, or the first week in August. I just googled “daylight time for today” and it says 14 hours 43 minutes for my area. We’ve been losing daylight, so that seems to line up.

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You have to factor in that outdoors the first hour of light and the last hour are so low in the sky that it’s really not usable light for the plant. My plants used to start to flower about mid-August too!

even my autoflowers start to fold up a bit about an hour before the lights turn off, and are up, praying, just before the lights come back on.
They know.

sktrrwn said:

Of course "we all know" cannabis "needs" at least 12 hours of dark to induce flowering, but how true is this?
Could a plant enter flowering with just, say, 11 hours of darkness? or 10 hours of darkness?

If 11 hours of darkness were to be enough, wouldn't it be beneficial for even bigger heavier buds considering the extra hour of light plants would be receiving each day instead of regular 12-12?

Tell me what you think or what you know

Click to expand...

Bravo ! Always question the norm. You sound like a science buff. I'd say, just follow nature's lead. I question everything, even the constants in the world of science.

sktrrwn said:

If 11 hours of darkness were to be enough, wouldn't it be beneficial for even bigger heavier buds considering the extra hour of light plants would be receiving each day instead of regular 12-12?

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Not when you use real lights. if I ran a 13 hour day instead of a 12 id have to dial my lights back or else they'd stress from too high of a DLI.

StonedGardener said:

Bravo ! Always question the norm. You sound like a science buff. I'd say, just follow nature's lead. I question everything, even the constants in the world of science.

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Algebra couldn't explain enough patterns around him, so man conceived more and more languages
(sciences) to communicate it's newly claimed knowledge of its world around it.
But like it's history, its science evolves continuously, AS they observe, and understand.....
....there is simply No way, to Know What, you Don't know..... until we see it (and A.I. is killing THAT!)...
And yet the most dominent sciences it relies on today, has zero basis is observable actions.
(who counted 6.24x10e18 electrons passing through that wire in exactly one second?)

oops.... content... I'm the kind of guy that adds 'puters and electronics to everything.
Hell, our beehives have their own websites with weight, H/T inside and out, rainfall, etc.....
the tent is not far behind he he. Since the webcam snaps a shot every 20 minutes, the inside
tent footage should be interesting, but my task will be overlaying realtime temp, humidity, VPD, etc
to show the effects on the plants

Outdoor is different a bit like @Phytoplankton mentioned, there is a difference between horizon sunrise and visible sunrise
According to my knowledge it's like 30-40 min difference.
So you have to factor that aswell.

I think outdoors the plants notice the daily minute or 2 of daylight loss and stay in flower because the daylight clock is constantly getting shorter. And the schedule is nice and uniform and can't get messed up. That's bro science but they seem to flower better outside than inside with the same 14 hrs of light

sktrrwn said:

Of course "we all know" cannabis "needs" at least 12 hours of dark to induce flowering, but how true is this?
Could a plant enter flowering with just, say, 11 hours of darkness? or 10 hours of darkness?

If 11 hours of darkness were to be enough, wouldn't it be beneficial for even bigger heavier buds considering the extra hour of light plants would be receiving each day instead of regular 12-12?

Tell me what you think or what you know

Click to expand...

Outdours in the northern hemerspher in most areas plants start flowering in about august. The dark hours were i am around that time are only about 9 hours maybe a touch longer towards the end. Most comercial strains can trigger on about 9 hours darkness. But in the outdoors the dark hours gradualy get longer which builds up more and more of the flowering hormone and less and less of the hormone that will cause the fast stretching. After much trial and error with indoor growing it was worked out that 12-12 indoors will trigger a good fast flower response with sufficent stretch the first third and pust out a good amount of flowering hormone to get a good finish with good yield and decent bud stacking, quality and look. If your not too fussed with that you can experiment but be prepered for the plant to express and fish with some diffrences eg continual stretch and shoot growth, elongated buds, losser buds, tighter buds, less yield, more yield, shorter finish time, longer finish time, changes in how fast the plant starts showing pistols ect ect and all sorts of other possibilities. Indoors 12-12 is know as forced flowering as it pushes the plant to flower and get the best out of it ( refering to most commercialy avalible strains.)
Ther are afew threads about this question allready if you want to look them up.

Ps i used to grow more indica leaning typez on 13hrs lights on and 11hrs dark. The flower time will extend abit but those extra acumilated hours of light did give me a slight yield increase ( with the cost of electricity now its probably not worth it). But try 13hrs of light on in flower for a sativa and you will probably see leafier stretchier buds that take much much longer too finish. And sometimes on them they will just keep growing brand new long stretched shoots and new buds while the other buds that the plant grew earier will ripen

sktrrwn said:

Of course "we all know" cannabis "needs" at least 12 hours of dark to induce flowering, but how true is this?
Could a plant enter flowering with just, say, 11 hours of darkness? or 10 hours of darkness?

If 11 hours of darkness were to be enough, wouldn't it be beneficial for even bigger heavier buds considering the extra hour of light plants would be receiving each day instead of regular 12-12?

Tell me what you think or what you know

Click to expand...

I know some strains, mexican sativas are some, but some strains seem to start flowering before 12 hours darkness. Those equatorial strains seem to flower more off time cues than simply light hours. As far as bud size, i dunno. Ive seen pics of clones grown under 10,11 and 12 hours light respectively. The ones that got 10 hours light were actually better developed. I aint saying final weight would be more, but, the plant stays shorter, bushier and builds bud quicker. I guess maybe this is the plant being tricked into thinking the days are shortening fast for it to have a chance to reproduce/finish. Best way to find out is try it out. Thats what the guy did whose pics i saw. Very enlightening.

What I want to know is : how much light is needed to be called night time. Because if I put the plants on the east side of the house and they don’t get sun in the evening for many hours, how does that affect the number of hours. Will they flower sooner

Well....At the end of the rainbow, it's always going to boil down to the genetics. My guess is that, the 12/12 system is kind of foolproof when growing indoors. But, no matter what you do and how perfect you make the environment, again, the genetics will decide the final outcome, anyway. I've used the Gas Lantern Technique several times and the plants loved it. In case you're wondering....The Gas Lantern Technique is where you have the lights on for 12 hours, then off for 5.5 hours, then on again for 1 hour and then off again for 5.5 hours -FOR VEG

And then to induce flowering, you go 11 hours on and 13 hours off for the first 2 weeks. Then for weeks 3 and 4 you reduce the light to 10.5 hours on and 13.5 hours off. Then for weeks 5 and 6, you reduce it to 10 hours on and 14 off. Weeks 7 and 8 you reduce it to 9.5 on and 14.5 off. By the last week of flowering, you should be at 9 hours on and 15 hours off.

Sounds weird, but it works like a charm.

Yep its mostly genetically dependant. Ive seen some strains pop pistils when light hit 16 hours. These were outside grown mexican bagseed sativas.

Outdoor grower here most of strains I have grown started to flower mid/late August.
Also depends how long they should flower fast ones sooner than slow ones in my experiance.