18 and 6 or 24

[Dirtdemon]

What are people’s thoughts on veg light cycle 24-0 or 18-6.
Myself I find that the plants are happier an healthier in 18-6. I never did a side by side comparison. Hmm maybe I’ll try that next winter. I am curious as to others thoughts on the subject.

 

[Bilbobudkin420]

The weather here dictated that I had my girls on 24h due to the crazy weather patterns here but now summers pretty much here Ive put em all to flower (12/12) but it gets so hot that the next round I do will have to have some darkness during the hottest hours. Its been going up to like 32-34C when the lights were on at like 2pm in the tent and they really didnt enjoy it lol. As soon as ive put em to flower theyve perked up again. But I reckon this is cos of the heat although im sure the break from light is welcome

 

[TorturedSoul]

I don't run more than 18 hours of light [EDIT: I occasionally do for seedlings and when rooting cuttings (although will just as often just stick them in the corner of the general grow space, so...)]. Yes, cannabis can exist as either a C₃ or a C₄ plant, but I believe that it gets a benefit from a regular dark period each day.

I did do some reading a while back that causes me to wonder if I'm incorrect in one of my assumptions (that one of those categories of plant species actually requires a dark period in the first place). On the other hand... I'm poor, lol. I don't relish the thought of contributing any more to the electric company's board of directors' vacation funds than I actually have to. While it may be that, in theory, I could shorten my vegetative period by - for example - 50% by running 24 hours of light per day instead of 18 (which would be... 50% more hours of light and, therefore, DLI)... It'd also mean that my house was that much hotter constantly. I have enough trouble sleeping as it is. Say what you want about the practice of running lights at night "because it's cooler then" - and I do understand the concept. But if I run lights at night, I'm not sleeping at night. At least not without running the air conditioner. And then it's a question of being able to (pay to) run the air conditioner OR run the lights. I might have to run it during hot days, of course. But I might not. Cannabis can take the heat better than I can, LMFAO. I melt above 68°F. Not really, of course - but I am miserable. Now... being used to being miserable ( ), I can deal with it. But, as mentioned, I cannot sleep, baring critical exhaustion. Plants are just fine at higher temperatures. And they'll still survive at higher temperatures than that.

I also like to get some age on cannabis plants before switching them to the flowering phase (personal choice). Ergo, the potential benefit of being able to force 50% more growth... is not a benefit TO ME.

As in all things in this universe, lol, YMMV, of course.

[Edit #2: Oh, for f*ck's sake. This forum... Correcting of screwed up "smilies" in progress...]

 

[Bilbobudkin420]

I don't run more than 18 hours of light [EDIT: I occasionally do for seedlings and when rooting cuttings (although will just as often just stick them in the corner of the general grow space, so...)]. Yes, cannabis can exist as either a C₃ or a C₄ plant, but I believe that it gets a benefit from a regular dark period each day.

I did do some reading a while back that causes me to wonder if I'm incorrect in one of my assumptions (that one of those categories of plant species actually requires a dark period in the first place). On the other hand... I'm poor, lol. I don't relish the thought of contributing any more to the electric company's board of directors' vacation funds than I actually have to. While it may be that, in theory, I could shorten my vegetative period by - for example - 50% by running 24 hours of light per day instead of 18 (which would be... 50% more hours of light and, therefore, DLI)... It'd also mean that my house was that much hotter constantly. I have enough trouble sleeping as it is. Say what you want about the practice of running lights at night "because it's cooler then" - and I do understand the concept. But if I run lights at night, I'm not sleeping at night. At least not without running the air conditioner. And then it's a question of being able to (pay to) run the air conditioner OR run the lights. I might have to run it during hot days, of course. But I might not. Cannabis can take the heat better than I can, LMFAO. I melt above 68°F. Not really, of course - but I am miserable. Now... being used to being miserable rolleyes, I can deal with it. But, as mentioned, I cannot sleep, baring critical exhaustion. Plants are just fine at higher temperatures. And they'll still survive at higher temperatures than that.

I also like to get some age on cannabis plants before switching them to the flowering phase (personal choice). Ergo, the potential benefit of being able to force 50% more growth... is not a benefit TO ME.

As in all things in this universe, lol, YMMV, of course.

Oh believe me... these plants were way big enough to flower. They were big enough a couple weeks ago lol. These gonna be some monsters

 

[TorturedSoul]

I hope they don't get too big. Remember the stretch that occurs during the first 40% of the flowering period. I've... managed to forget the significance of that a time or two. Tended to not go especially well .

 

[Perfect Sun LED]

Over the years, I have tried many cycles for veg and flower, for photos and autos. I found 18-6 works best for veg and best for autos. You can get flower time a bit short for photos by slowly going from 12/12 to 11-13, but not much. My lights already reduce the time because of the sun spectrum.

 

[TripleBeam]

18/6. Plants need darkness.

 

[Fuzzy Duck]

24/0 Mmm gave it go just the once & that is all i have to say about that !

I use 16/8, just makes it a little cheaper on the electric bill But ye plants need sleepy, sleepy time... i'm not sure if anybody has done a survey on what cannabis requires for lights off/night time hours yet for best growth ?

 

[TorturedSoul]

i'm not sure if anybody has done a survey on what cannabis requires for lights off/night time hours yet for best growth ?

I saw one... must have been a year and a half or so ago. Sets of identical plants (clones), mirrored grows. Lighting schedule varied from 16/8 to 24/0 in the vegetative phase. Harvests were weighed and the winner was... Well, I wish I'd thought to bookmark the thing, lol. I think it worked out that it got better to 18 hours, then some slight improvement to 20 hours, then slightly less ("diminishing returns") after that. I can't swear to the specifics, but I do remember that above 20 hours of light worked out to be a waste of electricity. Not sure about time (whether or not the upper end ended up being slightly shorter grows) - and this was only ONE experiment. But, yes, it has been done. Someone with decent web-searching ability ought to be able to find it. It was on a cannabis forum, but IDK which one.

Anyway, be careful to pay attention to the actual setup/conditions when looking at people's "experiments," because they don't always use clones from the same mother, don't always have identical grows, don't even always use the same lighting. (Which would make the results questionable at the very least.) And look for ones that go all the way through to harvest. That might seem to be counterintuitive, but it isn't, IMHO.