24 hours of light or 18/6 ????

I always do 24/0 for about 10-14 days then switch to 12/12

My plants get huge within those 10-14 days, nearly double what I see most people's plants are at 2 weeks.

superbak3d said:

I always do 24/0 for about 10-14 days then switch to 12/12

My plants get huge within those 10-14 days, nearly double what I see most people's plants are at 2 weeks.

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I believe that is because you know what you're doing, have excellent light intensity, and keep your plants healthy and strong. I don't believe it's the extra light hours, itself.

I run 24 hrs only... the plants will grow 30% faster with 24 hr light, compared to 18/6 .... you can save $ on the electric bill with 18/6 but the 30% is worth it to me, and they are ready faster, everyone likes that...

I would like to add that I'm not claiming 18/6 to be the absolute best. I'm just pressing for info. I've used 24/0, myself, and wasn't impressed. Yes, they grew great, but not noticeably better than 18/6, so I switched back. I'd like to see some side-by-side comparisons, or something similar, because I'm more than willing to change my opinion, if proven wrong. I'm all for learning, always.


Also, I believe that under controlled experimenting, that neither 18/6 or 24/0, would be the best setup. IMO, it would end up being a slightly longer photoperiod than 18/6, perhaps something like 19.5/4.5, or 20/4. Who knows, it could even end up being 24/0, IDK. What I am saying, is that I've never seen any clear proof that 24/0 is the best setup, and was hoping to see some real evidence, either confirming, or disproving, that.

Ed Rosenthals book "Got a question ask Ed ..the encyclopedia of marijuana" .... test result proved the same plant grows 30% bigger under 24 hrs compared to 18/6 .... its a wrap, facts are fact ; test and result its an easy to do btw...

^Okay, now ask Mr Ed, how 25% more light, is capable of achieving a 30% increase in growth? IDK, but I still have my doubts?

Hmm....I stuck my foot in my mouth, on that one, didn't I? That's a 33 1/3% increase in light. My bad.lol

At any rate, he is basically saying that there is basically nothing happening during the dark period, which is total BS. Yes, I realize that the his numbers say there is 3 1/3% growth there, which is practically nothing.

I wouldn't doubt that there is some increase in growth, using 24/0, but it's nowhere near 30%.

ive done both. I used to do 24 all the time but just found that it only adds a few extra days to get to a certain height. The benefits of havin a lights out period def outways the few days you gain from 24 hours. less heat if you leave your fans on it really gives your space time to cool.. any foliar sprays or pest control issues you have are always best given just before lights out or leaf burn can occur.

well thats my view anyway xx

Heres my opinion:

I think 18/6 is better.


I used to use 24/0...i was growing 3 plants under fluros on 24hrs...But their growth was slow.

So i switched it to 18/6...and i noticed faster, bushier growth within a few days of the switch.

Thats just my experience.

and as for electricity you have a cheaper rate from 10 untill 10 during the night thats 12 hours so for 18 hours you need another 6 hours at the more expensive day rate to run 24 you would be having 12 hours at the more expensive day rate may not seem much but if you work it out for the year i bet you anything that it works out cheaper on 18 hours!!!!!!!

LetricBud said:

Heres my opinion:

I think 18/6 is better.


I used to use 24/0...i was growing 3 plants under fluros on 24hrs...But their growth was slow.

So i switched it to 18/6...and i noticed faster, bushier growth within a few days of the switch.

Thats just my experience.

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On second grow now - did 18/6 from start on first grow b4 switch and 24/0 on this ~ up to other day when i thought about the leccy bill. From what i have seen, the plants have seemed to grow more bushy since switching to 18/6, tbh i didnt see all that much growth on the 24/0. I suppose i thought about it like this ~ What does mother nature do? certainly not natural to be in a constant state of light, and many outdoor growers have monsters. I think it might actually do the plants some good to have a state of rest, just like most things in life lol I know i feel healthier for having my rest hehe

Just my 2p's worth- but i dont claim to be an expert in any way

^Agreed. My plants grow as much at night,(or very close) as they do during lights on. Typically, if they've grown 1/4" during 'lights on', they grow about 1/4" during 'lights out', that very same night. It's not stretch, either. My plants are very bushy...

Agent Provocateur said:

On second grow now - did 18/6 from start on first grow b4 switch and 24/0 on this ~ up to other day when i thought about the leccy bill. From what i have seen, the plants have seemed to grow more bushy since switching to 18/6, tbh i didnt see all that much growth on the 24/0. I suppose i thought about it like this ~ What does mother nature do? certainly not natural to be in a constant state of light, and many outdoor growers have monsters. I think it might actually do the plants some good to have a state of rest, just like most things in life lol I know i feel healthier for having my rest hehe

Just my 2p's worth- but i dont claim to be an expert in any way

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well put, Provocateur

yea i rly think the rest period helps.

i get clones at 2-3inches put em in soil and under 400watts 24/0 then after a week 22/2 then after another week 20/4 then one more week 19/5 and i stay there till i switch to 12/12..all to there own..and just so u all know darkness allows roots to grow faster

they use theirt stored energy at night from the light time so less light then less ni9ght time energy to use, plants dont rest.