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Increased light schedule late flower for faster finish

Creeperpark

Well-known member
Mentor
Veteran
So I’m seeing some people on YouTube talk about increasing the light schedule during late flower from 12/12 to 20/4 or similar has anyone had any experience with this
Anything unnatural is going to affect the plant in some way. I have seen different photoperiods, like turning off the lights for a few days before harvesting, dropping the light hours to add more lights, or reducing the lights. Raising the lights and timed blackouts or turn-ons during the darkness. Using the long flowering photoperiod in flowering will cause an imbalance of flowering hormones. Raising the veg hormones during flowering will impact flowering hormones resulting in the same effects as smoking vegative leaf.

What are the plant hormones for vegetative growth?
5 groups of plant-growth-regulating compounds. There are five groups of plant-growth-regulating compounds: auxin, gibberellin (GA), cytokinin, ethylene, and abscisic acid (ABA). For the most part, each group contains both naturally occurring hormones and synthetic substances.

What plant hormone stimulates flowering?
Florigen

Florigen, a proteinaceous hormone, functions as a universal long-range promoter of flowering and concurrently as a generic growth-attenuating hormone across leaf and stem meristems. google

Keep it simple for the best weed.
 

Rocket Soul

Well-known member
So I’m seeing some people on YouTube talk about increasing the light schedule during late flower from 12/12 to 20/4 or similar has anyone had any experience with this
Thats sounds very wrong, if anything you could decrease the light schedule to 11-13 or 10-14. Look around the site and youll find evidence on this helping hard to finish strains. Going the other way just sounds nutty, hermie inducing. If you go all the way to 24 hours light your plant will go to reveg and revert to vegg after some time of fairly crazy looking growth, aka monster cropping.
Youtube is not the best source of knowledge tbh, its the last refuge of the grow-broiest. You can safely ignore those videos and every other recommendation from the same content creator. Going against rationally founded traditional knowledge has apparently become a virtue in todays conspiracy flooded culture.
 

Colliery boy

New member
I wouldn’t personally… more light (18h or more) = reveg territory and new shoots.
In nature the light drops, they don’t need more light… they have plenty of starch stored in the leaves bound up in the chlorophyll for this reason.
🤔
No need to reinvent the wheel 🛞

I wouldn’t personally… more light (18h or more) = reveg territory and new shoots.
In nature the light drops, they don’t need more light… they have plenty of starch stored in the leaves bound up in the chlorophyll for this reason.
🤔
No need to reinvent the wheel 🛞
Anything unnatural is going to affect the plant in some way. I have seen different photoperiods, like turning off the lights for a few days before harvesting, dropping the light hours to add more lights, or reducing the lights. Raising the lights and timed blackouts or turn-ons during the darkness. Using the long flowering photoperiod in flowering will cause an imbalance of flowering hormones. Raising the veg hormones during flowering will impact flowering hormones resulting in the same effects as smoking vegative leaf.

What are the plant hormones for vegetative growth?
5 groups of plant-growth-regulating compounds. There are five groups of plant-growth-regulating compounds: auxin, gibberellin (GA), cytokinin, ethylene, and abscisic acid (ABA). For the most part, each group contains both naturally occurring hormones and synthetic substances.

What plant hormone stimulates flowering?
Florigen

Florigen, a proteinaceous hormone, functions as a universal long-range promoter of flowering and concurrently as a generic growth-attenuating hormone across leaf and stem meristems. google

Keep it simple for the best weed.
Thanks for the knowledge man
 

MROrganicGreenz

Active member
I have to take a deeper look again, but there were some commercial growers in USA that did a 20/4 in the last two weeks to get heavy gains without (obvious) negative aspects. Its not just Youtube imo but I would be sceptical. Imho this also depends heavily on the strain / chemo- /phenotype you are growing. Its not for all plants. But if commercial growers hunt for plants that work fine with that, doesnt mean homegrowers could do that.

Also: Whats to win? Few more grams for risk of revegging or late herming? I think its interesting for scale but in homegrowing there is methods that have a higher lever for improvement than "snake oil" and bro science.

I always ask myself: Why the hunting for more and more gainz per watt? Stressing plants possibly shifts cannabidoid and terpen composition and not always to the best (imo). So rather think about a perfect finish with decreasing light hours and watering.

If you are interested in more authentic compositions, rather consider putting UVB light in or living soil or sth like that. Even KNF could be a way to go, but I would also be sceptical there (depending on space =D)

Greetings
 

Rocket Soul

Well-known member
I have to take a deeper look again, but there were some commercial growers in USA that did a 20/4 in the last two weeks to get heavy gains without (obvious) negative aspects. Its not just Youtube imo but I would be sceptical. Imho this also depends heavily on the strain / chemo- /phenotype you are growing. Its not for all plants. But if commercial growers hunt for plants that work fine with that, doesnt mean homegrowers could do that.

Also: Whats to win? Few more grams for risk of revegging or late herming? I think its interesting for scale but in homegrowing there is methods that have a higher lever for improvement than "snake oil" and bro science.

I always ask myself: Why the hunting for more and more gainz per watt? Stressing plants possibly shifts cannabidoid and terpen composition and not always to the best (imo). So rather think about a perfect finish with decreasing light hours and watering.

If you are interested in more authentic compositions, rather consider putting UVB light in or living soil or sth like that. Even KNF could be a way to go, but I would also be sceptical there (depending on space =D)

Greetings
This sounds like a more rational reasoning for adding hours to final weeks; adding yield. But iirc the adding of hours at end of flower there was some loss of thc; the study was posted in the led bud quality thread some months back.
 

Dr.Dutch

Well-known member
Dr. Bugbee had the same dump idea, so i don't think it can be all that dumb ;) In one of his videos about grow myths, he covered the topic of keeping plants in the dark before harvest to increase THC. That would be complete nonsense biologically, as THC is a secondary plant compound that can only be produced with light.

He suggested that it might actually be more beneficial to give the plant significantly more light during the last few days (just a few days, so there's no risk of re-vegging or hermaphroditism, which only occurs after prolonged interruptions of long nights) to push it a bit more at the end.
 

Douglas.Curtis

Autistic Diplomat in Training
In my studied opinion, mixed with a dash of personal experience, your results will depend heavily on strain, conditions and timing.

When lighting is switched back to veg the plant -will- go back to veg. However this does take a bit of time to happen. The additional light is going to provide a boost of growth for sure, but at what cost to quality? At some time point you'll begin noticing extra stem length (they begin stretching) in the flowers, and shortly after you'll notice they've started to become 'fluffier' flowers.

Since you're not going to see new trichomes forming and maturing in 2 weeks, the extra growth will tend to slightly decrease potency.
 

norm

New member
I'm trying a version of this, I needed to veg some new plants in my tent, but one of my plants from the last round isn't finished. I increased the light from 12/12 to 13/11 to keep the new plants from flowering, but still have my 8-9 week? (I don't keep track lol) lady in there. It's been 3 days and it doesn't seem to be causing problems so far.
 

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Rocket Soul

Well-known member
In my studied opinion, mixed with a dash of personal experience, your results will depend heavily on strain, conditions and timing.

When lighting is switched back to veg the plant -will- go back to veg. However this does take a bit of time to happen. The additional light is going to provide a boost of growth for sure, but at what cost to quality? At some time point you'll begin noticing extra stem length (they begin stretching) in the flowers, and shortly after you'll notice they've started to become 'fluffier' flowers.

Since you're not going to see new trichomes forming and maturing in 2 weeks, the extra growth will tend to slightly decrease potency.
I agree, if you wanna increase hours its better to do it in the start, switch to 14/10 (but this may result in a longer stretch transition, then slowly go from 12 down to 10 as you go from mid towards finish. There are also some genetic traits dont come out on 12/12 aswell from what i hear.
 

ThaiBliss

Well-known member
Veteran
This is a fascinating question. For sure it is strain dependent. From experience I can tell you that tiny changes can have huge consequences.

I grew a Neville's Haze freak pheno. It took 18 weeks to flower indoors at 12/12. It was the best weed I ever smoked, and I have had plenty of Thai Sticks in my life, arguably the strongest weed in history. The next grow from the same cutting I modified the schedule slightly. I reduced the light timing incrementally, slowly, until it was 10 hours on and 14 hours off. It looked finished in 16 weeks. I thought I was a genius, until I smoked it. It was hay.

On the other side of the spectum, I've heard that the Thai growers have two plantings between July and September. The plants finish between December and March. This means that light cycles are increasing at the finish. Again, these Thai growers are arguably the best on the planet.

I would love to hear about any experiments you do.
 

Rocket Soul

Well-known member
This is a fascinating question. For sure it is strain dependent. From experience I can tell you that tiny changes can have huge consequences.

I grew a Neville's Haze freak pheno. It took 18 weeks to flower indoors at 12/12. It was the best weed I ever smoked, and I have had plenty of Thai Sticks in my life, arguably the strongest weed in history. The next grow from the same cutting I modified the schedule slightly. I reduced the light timing incrementally, slowly, until it was 10 hours on and 14 hours off. It looked finished in 16 weeks. I thought I was a genius, until I smoked it. It was hay.

On the other side of the spectum, I've heard that the Thai growers have two plantings between July and September. The plants finish between December and March. This means that light cycles are increasing at the finish. Again, these Thai growers are arguably the best on the planet.

I would love to hear about any experiments you do.
Ive smoked increasing light hour weed which finished flower around mid june summer time, arguably the strongest stoniest ive ever smoked. My guess finishing in full summer uv, sunkissed and at altitude had something to do with it. It wasnt a planned thing, a happy mishap of a friend of mine and his gluetrap elite clones
 

mr.brunch

Well-known member
Veteran
13/11 won’t stop flowering- I flower on 13/11 for the first 3/4 weeks and they go fully in just as fast as 12/12
I think the trigger is meant to be around 14.5 hours

For example these gorilla haze are at 22 days, all on 13/11
1731520570765.jpeg
 

CocoNut 420

Well-known member
There's lots of variables with strains and photo responses.
I increased from 12-12 to 13-11
It was growing like a typical plant.
Screenshot_20240204_202705_Gallery.jpg

I binned another plant it was too far out and 1 other seedling and two clones were unaffected by the change.
 

CocoNut 420

Well-known member
I watched a yt link someone posted here a while back its very interesting, detailed, varied and no bro lol.
These pics from it are different hrs after flipping I'm sure some of you will have seen it, if you've not I'd recommend it.
Screenshot_20241016_163952_Brave.jpg
Screenshot_20241016_163944_Brave.jpg
Screenshot_20241016_163911_Brave.jpg

Come to think about it links get deleted, idk but if you're interested I'll dm you the link?
 
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