What flips a photoperiod plant?

What flips a photoperiod plant? A shortening day length (increasing darkness) say going from 18/6 to 16/8 or a resolute 12/12

Yes the term photoperiod means flowering is triggered by a certain amount of daylight.

With cannabis the "flip" is turning the light cycle to 12 hours on and 12 hours off to trigger flowering.

Photoperiod - Plant photoperiodism can also be defined as the developmental responses of plants to the relative lengths of light and dark periods. They are classified under three groups according to the photoperiods: short-day plants, long-day plants, and day-neutral plants.

Modern Selections said:

Yes the term photoperiod means flowering is triggered by a certain amount of daylight.

With cannabis the "flip" is turning the light cycle to 12 hours on and 12 hours off to trigger flowering.

Photoperiod - Plant photoperiodism can also be defined as the developmental responses of plants to the relative lengths of light and dark periods. They are classified under three groups according to the photoperiods: short-day plants, long-day plants, and day-neutral plants.

Click to expand...

I haven't tried this yet but going from 16 hours of daylight to 14 hours of daylight will not flip the plant?

brogro said:

I haven't tried this yet but going from 16 hours of daylight to 14 hours of daylight will not flip the plant?

Click to expand...

Depends on the plant

There have been studies arguing that incremental light schedule change is beneficial but flipping to 12/12 always works. Don't overthink things, I say.

8 hours darkness might flip some but 12 is a definite.

It's the period of continuous darkness. It's geneticly dependent anywhere from 9-11.5 hour dark time. You only need to interrupt the dark period for about 30 minutes to prevent blooming

Most plants require 12/12 to trigger flowering indoors.

shnkrmn said:

There have been studies arguing that incremental light schedule change is beneficial but flipping to 12/12 always works. Don't overthink things, I say.

Click to expand...

I want to cut down on electric use and I don't want to flip yet

LED lights use very little electricity. If already using an LED and want to further reduce electric usage, run the main light for 10-12 hours and then use a single 19 watt led light bulb for a few hours after main light is off to prolong veg.

Outdoors they flip mid to late July, not near 12/12 but darkness has increased maybe an hour from the june solstice. Indoor i can tell you even seedlings will flip under 12/12 after the second or third set of true leaves.

Its the flower hormone. It forces flower when it reaches critical stage. Every day in veg the flowering hormone builds but by the time the light comes back on it causes it to drop again. When the dark hours reach the point were that balance tips and the hormone level is built that high that due to the shorter daylight hours it isnt enough to drop it below the critical point hhaving this happen daily it triggers flower.Plants from different areas of the planet adapt to their conditions and light hours so the trigger hours will be different with plants coming from different areas. Eg some areas its near 12-12 year round so the plant wont trigger propely until the dark hours is slightly more than light ie 12.5 dark - 11.5 light. In areas were most indicas are found they can trigger at 9.5 dark - 14.5 light. Different types have different trigger points. This is how the photo plant works.

brogro said:

I want to cut down on electric use and I don't want to flip yet

Click to expand...

Flowering is triggered by longer periods of *uninterrupted* darkness. You could do the "gas lantern routine" and interrupt the dark period for an hour in the middle of the night, and that should keep them in veg.

Something like 12 hours lights on, 5.5 hours off, 1 hour on, 5.5 hours off. That's only one extra hour of lights on, then when you're ready to flip you just turn off that one-hour interruption

It is better to just extend the lights on cycle than interrupt with light during the dark cycle. Some plants freak out with the wonky schedule. Just add a couple hours to the light cycle with a weak light.

I use led rope lights in my greenhouses. Doesn't take much light at all to maintain vegetative state.

I have seen plants that have enough dark daily to push the flowering hormone high enough to flower, but then not enough light enough light hours to push the flowering hormone down enough so its in veg. What happens is you get veg growth with strange semi flowering points. Just stretched out weird flowers that dont have enough darkness to push the plant properly into flower. So be careful messing around with light hours and dark hours if you dont know exactly what your doing. Ive also seen plants that have just enough flowering hormone to trigger flower but to much light so they are in semi veg. The plant will build buds then out of the buds grow new branches and fresh flowers grow on these while the other flowers are going ripe. Just stick to the many years tried and tested methods unless you know what your doing and how to manipulate the hormones.

brogro said:

What flips a photoperiod plant? A shortening day length (increasing darkness) say going from 18/6 to 16/8 or a resolute 12/12

Click to expand...

you dont need to bring it to 12/12 just the 12/12 for a few days will activate it.allsoo not all strains need 12/12 some will go up to 14/10

I sometimes think complex light cycles and days that are other than 24 hours are just asking for a Fuck Up.

brogro said:

I want to cut down on electric use and I don't want to flip yet

Click to expand...

Run your lights on 12/12 with a 1hr interpretation in the middle of your dark cycle

hillbill said:

I sometimes think complex light cycles and days that are other than 24 hours are just asking for a Fuck Up.

Click to expand...

Can be fun to play around with though. How about 3-4 different lighting schedules on one monster 10ft indoor plant? You could pull the big main branches into multiple different tents right around it (the main area\pot kept in perpetual veg), and induce them to flower at different times, with crazy flip flopped schedules or whatever. Pull them right through the ducting ports and up into a scrog net. The main plant\root stock won't care, because the hormones are only localized the the sections that are triggered by the change in light anyway. The hormones don't travel back down and trigger the rest of the plant in any way that is..

The real question, is how would the roots go about transporting whatever macro/micro nutrients are needed to the different sections of the plant all partitioned off like that with completely different cycles? If one or 2 of the main branches are in flower in some of the tents at any time, will the roots/main stalk section that is perpetually in veg just keep all the nitrogen for itself? Would you expect to see deficiencies in one area or the other, or would the plant divide it up equally overall, sending it wherever it needs, even though the roots are technically still in a vegetative state?..

brogro said:

I haven't tried this yet but going from 16 hours of daylight to 14 hours of daylight will not flip the plant?

Click to expand...

My current grow flowered when I reduced the light to 14 hours on 10 off.