The 24/0 - 18/6 discussion

Alright, someone please give me a good reason not to go 24/0 for veg!!!!
Not anecdotal stories. Science! I have used 24 hours and it has been amazing. I need to know what the difference is, if any, using 6 hours of dark.

Thanks!

Also, are there threads about this topic already? if so link and I will delete this one.

the best growth is to closely duplicate nature, does the sun shine anywhere on plants 24/7? No....Simple as that. There is a reason for the "downtime" & the plants do most of their growing during this time. Every living thing needs rest, plants included.

This is anecdotal though. Plants do not need rest like we do. Photosynthesis requires light. I don't see the reason to rest them during vegetative growth. We are not simulating nature here. We are growing them in a controlled, manipulated environment. What type of growth supposedly occurs in the dark during the vegetative phase?

The only logical reasons I know of to go 6 dark are for electricity and heat concerns. 24 on doesn't cause Hermies. Doesn't slow growth. In fact, it is 6 more hours a day of photosynthesis.

i did use 24/7 but i noticed little growth of my plant then turned to 18/6 and my plant was growing day by day

keeping lights on for 24 hours is a waste of electricity they many not need to sleep but i want to mimic the sun by giving the plants a power down time aka darkness

they need to rest like us plus you will get very skinny long plants if u do so not worth it at all dont do 24 hrts straight never

I an 3 for 3 with 24/0. Dense, healthy, huge girls! I need to know why they need dark!

Ask Ed: Ed Rosenthal

One way in which plants are categorized is by the way they gather and handle carbon dioxide. Cannabis is a C3 plant. It uses the CO2 it gathers during the light period, when it is photosynthesizing. Plants designated C4 also gather CO2 during the dark period for use during the light period. Many C3 plants, including cannabis, do not need a rest period. They continue to photosynthesize as long as they are receiving light.

The plant's photosynthetic rate determines its growth rate because the sugars are used by the plant to build tissue and for energy. Cannabis under continuous light will grow 33% faster than the same plants on an 18-6 light regime

the real arguement for 18/6 is that 24/0 showed no more growth than 18 hours in testing ... save a little on the light bill and give 6 hours of dark .... same diff . less juice .....


no I dont have the link on hand .. but if u wanna call me on it , ill look for it ....

I do both and notice bugger all difference other than an annoying light while trying to sleep, a higher electricity, more money on nutes etc due to drinking more. No noticeable growth difference, i find it hard to find a reason to bother with 24/0, only reason i'm doing it now is to force re-veg. Personally my short opinion is this though, why do people care so much, there is no discernible difference else we'd all be doing it and be teaching people to do this.

I just want to know either way! Everything I have read, that isn't opinion, says that 24 hours of light is best. Cannabis doesn't need darkness at all. Only to trigger and maintain the flowering cycle. Does anyone have any evidence otherwise?

tip top toker said:

I do both and notice bugger all difference other than an annoying light while trying to sleep, a higher electricity, more money on nutes etc due to drinking more. No noticeable growth difference, i find it hard to find a reason to bother with 24/0, only reason i'm doing it now is to force re-veg. Personally my short opinion is this though, why do people care so much, there is no discernible difference else we'd all be doing it and be teaching people to do this.

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Because we're trying to accomplish something here. I don't believe that there is no difference. Light causes photosynthesis to occur. Therefor there IS a difference.

Jamblay said:

Because we're trying to accomplish something here. I don't believe that there is no difference. Light causes photosynthesis to occur. Therefor there IS a difference.

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Everything you have read scientifically points towards it being beneficial, but a lot of folk have put the science into practice and concluded that there's fuck all noticeable difference so why bother. I'm not trying to be mr argumentitive, if there was a desirable difference, then i'd do it, it would only make sense, but i don't so just use 18/6.

One thing i've not read up on is that root growth occurs more in the dark period than the light, but i've not read any studies on that, or if i did i forgot it all haha, but i'll see if there's anything behind that or just a wives tale.

I had the same question a couple years back. I have two separate veg rooms so i put it to the test to see the difference. The only difference between the two rooms was not in plant growth, but in energy consumption. So the only reason I use an 18/6 schedule is because it saves some power and promotes the same amount of growth. I'm not going to tell you that it will make your plants grow faster because i don't think it will. Try this same experiment on your own and document plant growth by taking measurments of leaves and plant height and stem width. A lot of folks believe that there is only one way to do things, so you are better off finding out for yourself. Respect

So it sounds like you're happy with your 24/0. If you have been doing 24/0 and you're happy why create a debate about it. If you want real evidence, proof, science!, then try it out for yourself and see.

Jamblay said:

This is anecdotal though. Plants do not need rest like we do. Photosynthesis requires light. I don't see the reason to rest them during vegetative growth. We are not simulating nature here. We are growing them in a controlled, manipulated environment. What type of growth supposedly occurs in the dark during the vegetative phase?

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Actually, that's exactly what I'm shooting for every indoor grow.

i like to watch the plants wake up while im smoking my first in the morning........

Yeah I have been very successful with 24/0. I was looking for reasons why I shouldn't or evidence that 18/6 is better. Or if there is any cycle that is superior. I have also read about root growth occurring more rapidly during the dark phase, but in my experience root growth has been just amazing in the Fox Farm Ocean Forest dirt. I'm switching to airpots, so it should be less of a concern. I wasn't trying to rile anyone up! It's just a frustrating topic for me. Electricity wise, its like 20 bucks a month. I've only got either a 600 hps or 400 mh on at any given time. I guess what I'm after is... is 18/6 better?
Evolutionarily speaking, cannabis does not seem to require dark for any function during veg. Flowering, of course. But Veg? A lot of people want to mimic nature, but I contend that this isn't the point of an indoor grow. At least in my view. I'm trying to use scientific methods to enhance nature.

wayno30 said:

i like to watch the plants wake up while im smoking my first in the morning........

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I do too! I'm on 7am to 7pm dark right now.

ya i just veg with 24 one less timer to worry bout

I'm not saying not to do 24 hours ... I just think its a waste of energy with nothing more to show for it ... if it works for ya and you dont mind paying a little higher energy bill ... by all means carry on ........