24-on 12-off light cycle

[Bean Genie]

I was joking about the elaborate prank but the implication is that the extra light hours will cause the plant to more actively produce flower during that time.

I have no idea whether that’s true, as you raise good points about heat and dormancy. I’d love to find out from someone with direct experience.

I’m not casting aspersions on this Weed World Magazine or Professor Lee, but I’ve never heard of either one. It’s certainly not a peer-reviewed study in an academic journal.

Ya I hear you GW. His book is $40 and if you read the review it is just kind of an outdated beginner guide.
His Facebook page has almost 0 action daily.
If this idea (from 2016) was a winner, I would hope we would have heard about it here by now.
I have a bunch of Ed Rosenthal write ups and have never heard about this but I’ll keep looking.
The article would be a rock solid piece if he had explained why and then shown results- instead it feels like it was ‘working’ after a few weeks and he wrote the article before any concrete results were verified.
I’m all for new ideas that will get us more weight but let’s see one person who has done this successfully before we need to go much further.

 

[SmokingWings]

I was joking about the elaborate prank but the implication is that the extra light hours will cause the plant to more actively produce flower during that time.

I have no idea whether that’s true, as you raise good points about heat and dormancy. I’d love to find out from someone with direct experience.

I’m not casting aspersions on this Weed World Magazine or Professor Lee, but I’ve never heard of either one. It’s certainly not a peer-reviewed study in an academic journal.

I just figure Professor Lee is a way to keep people, like police or thieves, from knowing the real name of a person growing in a state or country where it is still illegal.

Your mention of peer-review got a smile. Skip the academic journals and let the guy start to get some peer-reviews from other average growers.

Just figuring that the plant produces more of everything it needs during the extra light session and that in turn causes to to supercharge the flowering process once the hormones have reached the right level.

There is a thread on this message board discussing how the Marijuana plant can grow during the 18-20 hours of light during the vegetating stage. The discussion got into why the plant does not need to have a longer period of dark during that stage. I can't remember the name of the article but am pretty sure that there was some active discussion in it at least 10 days ago.

 

[Bean Genie]

I just figure Professor Lee is a way to keep people, like police or thieves, from knowing the real name of a person growing in a state or country where it is still illegal.

Your mention of peer-review got a smile. Skip the academic journals and let the guy start to get some peer-reviews from other average growers.

Just figuring that the plant produces more of everything it needs during the extra light session and that in turn causes to to supercharge the flowering process once the hormones have reached the right level.

There is a thread on this message board discussing how the Marijuana plant can grow during the 18-20 hours of light during the vegetating stage. The discussion got into why the plant does not need to have a longer period of dark during that stage. I can't remember the name of the article but am pretty sure that there was some active discussion in it at least 10 days ago.

I think I remember that as well, but in my case it may have been referring to autos. People were arguing they need SOME sort of dark- but someone here explained that cannabis is a C3 plant and can live without a dark cycle.
With photos though, they need a dark cycle to start flowering, as you know.

Long but great scientific explanation of C3 here Cannabis Photosynthesis

 

[013]

I could be wrong here.... usually am ha ha. Why 24/12 works is you are simply getting more total lights ON hours over the plants life cycle. Oooh let me rephrase that .... If it works as claimed then more light hours would be the reason, I can’t confirm or deny that it works but it does in an offhand way kinda make sense.

Funny thing too but I’ve heard The Celt mentioned that once buds are truly “set” you can extend beyond 12 hours of lights on and stay in flower without triggering a reveg. Maybe he can quote the source. Anyway why aren’t more of us doing that... more light = more growth right? I know they require darkness to stay in flower but what about running your veg cycle as normal then flipping 12/12 for 3 weeks until buds are fully set then dialing up to 14 on and 10 off, then few weeks before harvest dial back down for finishing and budswell etc.

Just like gas lantern routine - in nature the sun never pops out for an hour in the middle of the night but we can trick plants with our lights and timers. Sure I’ve ran autos 24 on for couple weeks no probs and yes you can run autos 24/7 from start to finish, tho most don’t to conserve $$

Truly stuff can be manipulated beyond what we think is normal but it prolly helps to embark on experiments when starting from seed otherwise - confused plants that can’t adapt. I’m a greenhorn, definitely not a pro - but that’s my take, please correct me wherever needed.

Edit to add I belive SmokingWings said it right - it’s the long nights that trigger hormones for flower but according to what The Celt said the long nights can be manipulated once the 3 week bud set is completed

 

[Grandma Weedstein]

Truly testing out this theory could get pretty expensive — for my income bracket, anyway — as you’d need two separate tents and lighting systems to compare clones under the 24/12 light cycle with clones (from the same mother) under the control 12/12 light cycle.

It seems like a worthwhile test, since it could legitimately show whether the plants will flower without disruption and whether there’s any increased yields or unexpected problems. However, I’m not intrigued enough to shell out $ for another tent and lighting system, fans, etc.

I suppose you could run clones from the same momma in the same tent sequentially — first under 24/12, then under 12/12, but it seems like other variables might be different. (A different time of year, so the ambient temperature might be higher or lower, and so on.) It might be close enough to get an idea, tho...

 

[013]

I have space but not the equipment so yeah $$ and I have other grow budget needs that take priority. Now if someone here took the challenge I would follow along. The sciencey stuff is not my wheelhouse! Yeah it’s crazy fascinating but it would take more than a few runs to see if results are consistent and repeatable

 

[Bean Genie]

I have space but not the equipment so yeah $$ and I have other grow budget needs that take priority. Now if someone here took the challenge I would follow along. The sciencey stuff is not my wheelhouse! Yeah it’s crazy fascinating but it would take more than a few runs to see if results are consistent and repeatable

I might think about it because I have a gap in where I want to start my next batch and I just happened to make a Dr Seedsman CBD (photo) clone that I could use for that experiment. I will have one of my 3 tents empty for just long enough that might work. I’ll see about that, could be fun. My journal has a couple weird things already so this actually sort of fits.
And if it doesn’t work, the worst that happens is it re-vegging and then I just go back to 12/12.

 

[Grandma Weedstein]

I have space but not the equipment so yeah $$ and I have other grow budget needs that take priority. Now if someone here took the challenge I would follow along. The sciencey stuff is not my wheelhouse! Yeah it’s crazy fascinating but it would take more than a few runs to see if results are consistent and repeatable

I mean, if it’s like 30-40% higher yield, or even 25%, then it would be so obvious that you could say with confidence it’s worthwhile. If it’s only like 3% then yeah, definitely would need replication to confirm and also would make me question the value.

It’d be confusing as hell to have the lights on and off during different times of the day, plus the point made by SmokingWings about temperature, etc., seems like it could be problematic.

I might think about it because I have a gap in where I want to start my next batch and I just happened to make a Dr Seedsman CBD (photo) clone that I could use for that experiment. I will have one of my 3 tents empty for just long enough that might work. I’ll see about that, could be fun. My journal has a couple weird things already so this actually sort of fits.
And if it doesn’t work, the worst that happens is it re-vegging and then I just go back to 12/12.

That would be totally awesome if you tested it — be sure to share a link to your thread so we can all follow your research!

 

[013]

Agreed with you both 13 & weedstein. A community grow with half dozen folks comparing notes

 

[Bean Genie]

I mean, if it’s like 30-40% higher yield, or even 25%, then it would be so obvious that you could say with confidence it’s worthwhile. If it’s only like 3% then yeah, definitely would need replication to confirm and also would make me question the value.

It’d be confusing as hell to have the lights on and off during different times of the day, plus the point made by SmokingWings about temperature, etc., seems like it could be problematic.

That would be totally awesome if you tested it — be sure to share a link to your thread so we can all follow your research!

Mine will for sure be in my perpetual journal in my signature. I’d love to do it along with a few people and compare methods and notes.
I don’t have to worry about temps, it’s about to get cold here and my garage stays between 70-80 all the time whether I have my 3 tents on or not. Sounds fun

 

[013]

Yes I’d have to $$ duplicate equipment to get there - new tent, 1 light, more fans & timers but mostly I’d have to reset my whole room to get there so it’s not viable for me now.... but I’ll sit in the back and shout obscenities- if you are down for that!

 

[Elvin]

I am not going to be trying this but it sounds like an interesting project for those who like to experiment.

The article does not get into why it works, just the claim that if the grower sticks with a light period of 24 hours and a dark period of 12 hours their plants will be ready to harvest sooner than if they had used the more traditional 12/12 schedule. The article then goes on to explain how to follow his suggestion of having the lights on for 24 hours and off for 12 hours using a 7 day programmable timer instead of the traditional 24 hour timer.

The 12 hour dark cycle works because the biologists have realized that the plant needs that much time to build up enough of the hormones needed to start and maintain flowering. The plant needs approx 12 hours of light for photosynthesis which provides the sugars, starches, etc needed for growth and maintenance. A certain amount of growth takes place during both the hours of light and dark.

While the author gets into how to program the timer to pull this schedule off he does not explain why the schedule works. He does not tell us just what is happening that the plant can finish the flowering cycle two weeks soon and do it without any loss in harvest weight.

A couple of starter articles that might help figure out what is happening during the extra hours of light and the regular 12 hours of no light. I have only done a quick read of them which is why they "might" help. The first one is very basic. The second link is to a sequence of short articles that are aimed at junior high to high school students (ages 12-17). The google search words were: do plants grow in the dark

Is a 24-Hour Light Schedule Bad for Plants?

Do Plants Grow Faster in Light or Dark?

Next up I will be looking through some of the articles in the search result page that appear to be linked to university web sites.

Weed is a C3 plant so it does not need to sleep.
Let's ask Ed:
"By Ed Rosenthal - Wednesday, February 20 2002
Tags: Ask Ed,CC29,GROWING,Indoor,Lights.
What are the best cycles for vegetation and flowering?
What is the best light cycle during the vegetative stage, 18/6 or 24/?
And which one will help the ladies go into their flowering cycle with the less stress?

Lamp Lighter,
New Brunswick, CT

Marijuana plantes photosynthesize as long as they receive light as well as water, air, nutrients and suitable temperature. Photosynthesis is the process in which plants use the energy from light (primarily in the blue and red spectrums) to combine carbon dioxide (CO2) from the air and water (H2O) to make sugar while releasing oxygen to the air.

Plants use sugars continuously to fuel metabolic processes (living) as well as for tissue building. The plant combines nitrogen (N) with the sugar to make amino acids, the building blocks of proteins. They are the substance of plant tissue. When the light is off, the plant's metabolic processes, respiration and growth, continue.

The plant can photosynthesize continuously so it produces the most energy and growth when the light is on, continuously. Continuous light does not stress the plant, which reacts somewhat mechanistically to it.

Plants under an 18-6 light-dark regimen are producing sugar only three quarters of the time. They are thus growing at only 75% of their potential. Leaving the light on continuously will result in bigger plants, faster, which leads to higher yields."

Stretch is very dependent on darkness (the plant "seeks" light in darkness) which is why you want some darkness.
24/0 results in short bushy plants. The suggested 24/12 light cycle sounds like weed forum nonsense, not anything based in science unless they are trying for a 24 for growth with the 12 to achieve a somewhat normal stretch. Seems kind of silly if that is what they want to do.
It's better to do 24/0 until it's ready to stretch, 18/6 to get the stretch then fill it out in 24/0 until the flip. More hours under light than the 24/12 BTW.
Personally I'm not going for quantity so it's the normal 18/6 then 12/12 for me; I've done the 24/0 and it turned normally 7 foot GG#4 into 5-foot bushes that really resembled an Auto that was under 24/0 light. If you need a lot of weight to squeeze or blast, sure, but quantity is not always what you want.

 

[Grandma Weedstein]

Weed is a C3 plant so it does not need to sleep.
Let's ask Ed:
"By Ed Rosenthal - Wednesday, February 20 2002
Tags: Ask Ed,CC29,GROWING,Indoor,Lights.
What are the best cycles for vegetation and flowering?
What is the best light cycle during the vegetative stage, 18/6 or 24/?
And which one will help the ladies go into their flowering cycle with the less stress?

Lamp Lighter,
New Brunswick, CT

Marijuana plantes photosynthesize as long as they receive light as well as water, air, nutrients and suitable temperature. Photosynthesis is the process in which plants use the energy from light (primarily in the blue and red spectrums) to combine carbon dioxide (CO2) from the air and water (H2O) to make sugar while releasing oxygen to the air.

Plants use sugars continuously to fuel metabolic processes (living) as well as for tissue building. The plant combines nitrogen (N) with the sugar to make amino acids, the building blocks of proteins. They are the substance of plant tissue. When the light is off, the plant's metabolic processes, respiration and growth, continue.

The plant can photosynthesize continuously so it produces the most energy and growth when the light is on, continuously. Continuous light does not stress the plant, which reacts somewhat mechanistically to it.

Plants under an 18-6 light-dark regimen are producing sugar only three quarters of the time. They are thus growing at only 75% of their potential. Leaving the light on continuously will result in bigger plants, faster, which leads to higher yields.

Readers with grow questions (or answers) should send them to Ed at: Ask Ed, PMB 147, 530 Divisadero St., San Francisco, California 94117, USA
You can also email Ed at AskEd@quicktrading.com, and send queries via his website at Quick Trading Company.
All featured questions will be rewarded with a copy of Ed's The Big Book of Buds from Quick Trading.
Sorry, Ed cannot send personal replies to your questions. "

Stretch is very dependent on darkness (the plant "seeks" light in darkness) which is why you want some darkness.
24/0 results in short bushy plants. The suggested 24/12 light cycle sounds like weed forum nonsense, not anything based in science unless they are trying for a 24 for growth with the 12 to achieve a somewhat normal stretch. Seems kind of silly if that is what they want to do.
It's better to do 24/0 until it's ready to stretch, 18/6 to get the stretch then fill it out in 24/0 until the flip. More hours under light than the 24/12 BTW.
Personally I'm not going for quantity so it's the normal 18/6 then 12/12 for me; I've done the 24/0 and it turned normally 7 foot GG#4 into 5-foot bushes that really resembled an Auto that was under 24/0 light. If you need a lot of weight to squeeze or blast, sure, but quantity is not always what you want.

LOL, I think we all share your skepticism and yet can’t help being intrigued! To be honest, the main reason I don’t want to try this is that I will inevitably get drunk and forget the plant is in the dark part of the cycle. It all just sounds too “out there” for a mostly-outdoor grower who only uses a tent and lights to “quality check” last year’s crosses...

 

[Bean Genie]

LOL, I think we all share your skepticism and yet can’t help being intrigued! To be honest, the main reason I don’t want to try this is that I will inevitably get drunk and forget the plant is in the dark part of the cycle. It all just sounds too “out there” for a mostly-outdoor grower who only uses a tent and lights to “quality check” last year’s crosses...

Even if no one else can join in, I'm still down to try it. The clone I will use was a fluke freebie I grew in the windowsill anyway, from a freebie seed, and I have an empty tent once I chop its Mom down on Sunday. It will just make my journal more well rounded. I love science, and being the first to do something. Later this fall I'll be doing the first ever CBG auto as well as CBD autos, and a bunch more interesting stuff. It will fit right in!

 

[Elvin]

LOL, I think we all share your skepticism and yet can’t help being intrigued! To be honest, the main reason I don’t want to try this is that I will inevitably get drunk and forget the plant is in the dark part of the cycle. It all just sounds too “out there” for a mostly-outdoor grower who only uses a tent and lights to “quality check” last year’s crosses...

I've done the 24/0 before and it does make the plant grow like crazy.
The problem is the stretch goes away and your photo will grow like a short bushy Auto that receives hardly any darkness (or none). Even after the flip the plant does not start stretching like it does after a normal 18/6 veg.
I can see where that would be desirable but it is not for me. Bushy plants equals a lot of popcorn that does not get much light unless you really trim and that is not what I want to spend my time doing.
I can see how increasing hours of darkness in veg can be used to control stretch in a short tent (you could veg longer for a larger plant instead of having to flip early to keep it short) but that is all I'd use it for myself.

 

[VetSmoke85]

Even if no one else can join in, I'm still down to try it. The clone I will use was a fluke freebie I grew in the windowsill anyway, from a freebie seed, and I have an empty tent once I chop its Mom down on Sunday. It will just make my journal more well rounded. I love science, and being the first to do something. Later this fall I'll be doing the first ever CBG auto as well as CBD autos, and a bunch more interesting stuff. It will fit right in!

I could give it a go in my little cabinet once this auto is done too. By then the temperature here should be cool enough. I have some photo seeds and a 7 day programmable timer. My rig hardly uses any electricity and I've got plenty of meds to last a while so that won't be an issue for me. I'm always game to try something crazy. It'll only be a small plant but will see if it shortens the flowering time. Interesting.

 

[Grandma Weedstein]

Even if no one else can join in, I'm still down to try it. The clone I will use was a fluke freebie I grew in the windowsill anyway, from a freebie seed, and I have an empty tent once I chop its Mom down on Sunday. It will just make my journal more well rounded. I love science, and being the first to do something. Later this fall I'll be doing the first ever CBG auto as well as CBD autos, and a bunch more interesting stuff. It will fit right in!

Right on!

 

[Grandma Weedstein]

I've done the 24/0 before and it does make the plant grow like crazy.
The problem is the stretch goes away and your photo will grow like a short bushy Auto that receives hardly any darkness (or none). Even after the flip the plant does not start stretching like it does after a normal 18/6 veg.
I can see where that would be desirable but it is not for me. Bushy plants equals a lot of popcorn that does not get much light unless you really trim and that is not what I want to spend my time doing.
I can see how increasing hours of darkness in veg can be used to control stretch in a short tent (you could veg longer for a larger plant instead of having to flip early to keep it short) but that is all I'd use it for myself.

The debate here adds another twist to the 24 hour light question — the proposal is to light for 24 hours alternating with 12 hours darkness during flower.

 

[Grandma Weedstein]

I could give it a go in my little cabinet once this auto is done too. By then the temperature here should be cool enough. I have some photo seeds and a 7 day programmable timer. My rig hardly uses any electricity and I've got plenty of meds to last a while so that won't be an issue for me. I'm always game to try something crazy. It'll only be a small plant but will see if it shortens the flowering time. Interesting.

Please be sure to share a link on this thread — this is a fascinating question that gets to the heart of cannabis botany.

 

[013]

I thot the parameters were testing 24/12 against a regular run. Something like 18/6 dropped back to 12/12.

Copy and paste from first paragraph of Prof Lee’s article..... ok buddy which is it?

possible. The disadvantage is a proportionate reduction in harvested bud weight.m heading element

The alternative long light cycle technique shortens the flowering cycle of plants without sacrificing bud weight.