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24 Hours Of Dark before switch to flower
- Thread starter shaggyballs
- Start date
nogutsnoglory
Member
Onset of flowering is definitely sped up, ive noticed formation of buds 3 to 5 days sooner when doing this.
Featherfoot
Member
I used to do that to let the flowering hormone build up quickly.
Don't know if it made them flower any quicker.
It might cause them to stretch more, you would have to do side by side experiments with plants that went straight to 12/12 to know for sure.
Don't know if it made them flower any quicker.
It might cause them to stretch more, you would have to do side by side experiments with plants that went straight to 12/12 to know for sure.
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nogutsnoglory
Member
I found this;
In cannabis plants, the normal presence of PFR switches off the flowering signal. The level of PFR is what you can manipulate by adjusting the photoperiod. PFR is quickly produced when plants are exposed to light that contains far red wavelengths. When there is light, the PFR and PR maintain a balance. When the sun goes down or the lights go out, the darkness gradually switches the PFR to PR. Because of this, PR levels gradually increase and the PFR gradually decrease during the dark period. The presence of PR is a neutral condition to the plants and essentially tells them nothing. When the light returns, or if a small amount of far red light interrupts the dark period, the PR immediately switches back to PFR. If the plant is without light long enough, the PFR will decrease past a tipping point. This decreased level of PFR signals the plants that Fall is approaching; and the plant begins flowering.
In short, the presence of PFR due to long hours of light and short hours of darkness keep the plants in the vegetative phase. If the plant experiences enough hours of darkness, most of the PFR turns to PR ; and the low level of PFR signals the plant hormones to begin flowering.
While simply changing to a 12/12 light cycle will induce flowering, there is a trick to jump start the process. Between the switch from an 18/6 to a 12/12 light cycle, let your plants sit in total, uninterrupted darkness for 36 hours. This will cause the PFR to drop substantially, giving the plants a strong signal to flower. After the 36 hours of darkness, begin the 12/12 light cycle. In a side by side experiment, I saw significant results from this method. Be sure to flush out high nitrogen “grow” fertilizers from your growing medium and change to a high-phosphorus “bloom” formula. Also, adding high potassium supplements for the first two weeks can help increase rapid bud development
In cannabis plants, the normal presence of PFR switches off the flowering signal. The level of PFR is what you can manipulate by adjusting the photoperiod. PFR is quickly produced when plants are exposed to light that contains far red wavelengths. When there is light, the PFR and PR maintain a balance. When the sun goes down or the lights go out, the darkness gradually switches the PFR to PR. Because of this, PR levels gradually increase and the PFR gradually decrease during the dark period. The presence of PR is a neutral condition to the plants and essentially tells them nothing. When the light returns, or if a small amount of far red light interrupts the dark period, the PR immediately switches back to PFR. If the plant is without light long enough, the PFR will decrease past a tipping point. This decreased level of PFR signals the plants that Fall is approaching; and the plant begins flowering.
In short, the presence of PFR due to long hours of light and short hours of darkness keep the plants in the vegetative phase. If the plant experiences enough hours of darkness, most of the PFR turns to PR ; and the low level of PFR signals the plant hormones to begin flowering.
While simply changing to a 12/12 light cycle will induce flowering, there is a trick to jump start the process. Between the switch from an 18/6 to a 12/12 light cycle, let your plants sit in total, uninterrupted darkness for 36 hours. This will cause the PFR to drop substantially, giving the plants a strong signal to flower. After the 36 hours of darkness, begin the 12/12 light cycle. In a side by side experiment, I saw significant results from this method. Be sure to flush out high nitrogen “grow” fertilizers from your growing medium and change to a high-phosphorus “bloom” formula. Also, adding high potassium supplements for the first two weeks can help increase rapid bud development
That's a useful explanation. I think it's not that clear though how much of a difference it would make when the grower is looking at a flowering period of 7 to 12 weeks.
I guess one could argue that in an outdoor grow where climate limited the ability to get in a full flowering before killing frosts, maybe that approach would measurably shorten the flowering period and thereby let the plant fit in where otherwise it would not be a viable fit for the region.
the person didn't say what the significant results were: bigger yield, shorter flowering time to harvest, etc.
tokersmoke
Member
I have done 36 hours darkness.In my experience the plants just get shocked but do bud up faster with less stretch but yield was compromised!When i pulled the plants out they where drooping badly.I dont have a side by side.So everything is just opinion.
Indoor gardening is about replicating Nature.This just seemed unnatural and unproductive.We add high power lighting that mimics the sun,add co2,Create a living soil and still cant manage to really give a "perfect" environment similar to the great outdoors.
Just my 2c Not knocking anyone who's using it and getting different results.
Indoor gardening is about replicating Nature.This just seemed unnatural and unproductive.We add high power lighting that mimics the sun,add co2,Create a living soil and still cant manage to really give a "perfect" environment similar to the great outdoors.
Just my 2c Not knocking anyone who's using it and getting different results.
Hillside Grower
Member
"The transmission of florigen -- and thus, the induction of flowering-- relies on a comparison between the plant's perception of day/night and its own internal biological clock"
aus2canibasiva
Member
(Opinions in red)
Iv'e read someone else's experience on extending dark period before flowering & it is as you say, "the plants just get shocked" Is what I remember the guy posting to.
It's a great way to induce flowering fast!! but there is a trade off & that is "yield is compromised"
This would be perfect for those who are on a tight time schedule & need to finish up there grow faster. I personally wouldn't want to use an extended dark period even if it does build up the (flowering hormone Florigen) because of the stress and yield compromisation.
That was my rational to!
Iv'e read someone else's experience on extending dark period before flowering & it is as you say, "the plants just get shocked" Is what I remember the guy posting to.
It's a great way to induce flowering fast!! but there is a trade off & that is "yield is compromised"
This would be perfect for those who are on a tight time schedule & need to finish up there grow faster. I personally wouldn't want to use an extended dark period even if it does build up the (flowering hormone Florigen) because of the stress and yield compromisation.
That was my rational to!
tokersmoke
Member
Thanks aus.Great discussion!!!!
Speaking about nature its gonna be in the 70s today after months of cold weather.I'm getting out this house and enjoying mother nature for all her beauty.
Speaking about nature its gonna be in the 70s today after months of cold weather.I'm getting out this house and enjoying mother nature for all her beauty.
aus2canibasiva
Member
Thanks Tokersmoke
Thanks Tokersmoke
Always up for a good discussion tokersmoke & yeah I love embracing a new change in weather, gives you a new perspective every time the season changes, good old mother nature
You sound like a good soul.
Hey while your out & about in beautiful nature Smoke a phat one for me & all the good people on ICMAG
Peace & Happy Growing.
Thanks Tokersmoke
Always up for a good discussion tokersmoke & yeah I love embracing a new change in weather, gives you a new perspective every time the season changes, good old mother nature
You sound like a good soul.
Hey while your out & about in beautiful nature Smoke a phat one for me & all the good people on ICMAG
Peace & Happy Growing.
"The transmission of florigen -- and thus, the induction of flowering-- relies on a comparison between the plant's perception of day/night and its own internal biological clock"
The last few words say a lot.
If your coming from 24 hour light, all your plants are sleeping at different times. So each will have a different perception of what just happened.
If your doing 18/6 then lights out is about when they were going to bed anyway. So if you use 24 hours of darkness starting then, you're not lighting them the next day, until bedtime. You have literally started to light them at night.
I'm running with the presumption that plants have a 24 hour rhythm that they don't particularly want disturbing. With this in mind, you may see signs of flowering earlier, but have lost days as they are forced to change shift. Presuming an 18 hour grow, and the 6 was extended to 24.
If you don't believe plants have a 24 hour rhythm, then start doing 16 hours on and 10 off. The 10 should keep most plants in flower, and 16 shouldn't break that. Each day will see more light hours. It's not a new idea.... Thread anyone?
Ibechillin
Masochist Educator
Edited, see post #31.
Last edited:
insomniac_AU
Active member
Personally I wouldn't do it, it's unnatural. The plant receiving 12 hours or more of darkness triggers it to flower anyway. There is thread at the moment asking why so many hermies these days. Not saying this will cause that but unnatural and unnecessary stress on the plant can't be good.
G
GatorGumbo
Many good tricks that turn good weed into great weed are how and when the grower stresses the plants unnecessarily.
