Not sure there’s a single right answer, since there are as many different grow styles as people… just looking for general observations. Tell me about your experience growing autos.
Do you think autos do better under 24-hour light, or do they prefer to get a little rest?
If they do need rest, is 20/4 good, too much, or not enough? 18/6 and 22/2 are also options I’d be open to.
Should I just pull up an online dice-roller and roll 1d4 to decide for me? 
I think all plants need some rest when they start to age. I would recommend 19 to 20 hours for autos. If that’s to much you will see it in the plants.
I’m running my autos on 18/6, the fogdogs start dooping by hour 16 the rk62 seems to handle it well.
My veg/auto area turns off midnight to 4:00am.
What I have often wondered is what a 10/2/10/2 type cycle would do to auto’s. Cram more “days” into a day
That’s good to know, I wasn’t even sure if autos had a DLI to watch for or not. I’m guessing it’s gotta be higher than for photos generally, but they can still get too exhausted to want more light and just give up for the day… for seedlings and the first week or two of veg, they don’t seem to be getting tired yet. Will they still do better with 20/4 though, to give them a little time for root-building? I seem to remember reading somewhere that they mostly extend their roots during the dark.
That might play merry hell with photos, I guess… I wonder if that would be enough to send them into flower while still giving them a lot of light, and if it would actually be effective? That would be an interesting experiment. Probably someone’s done it already, but I’m not feeling the Google-fu right now… for autos, I obviously have no experience, but I’m not sure why it would make much of a difference from 20/4. It shouldn’t speed up their flowering, since that’s based on real time, not our abstract calendars which can be remade at the drop of a zucchetto or the death of an emperor. Would the DLI be reset by two hours of rest like that?
First couple weeks I was running 24hr, they didn’t start showing fatigue till they started flowering so I moved down to 18/6 I’m not going lower because I don’t want to lose yield on the rk62 and she’s liking it more than the fogdogs don’t.
Perfect, at least I know what to do right now. 
I’ll keep them in 24-hour, then see when they start getting exhausted and adjust from there. That 10/2/10/2 idea sounds interesting though, I might have to work in an experiment on what that does at some point… I could see it being useful to extend the light-tolerance of flowering plants, especially if it somehow works on photos, but I could just as easily see it causing herms everywhere you look.
I’m admittedly just kinda winging it with the autos. Fogdogs got fucking huge. Like 5ft tall now at 6ish weeks
Doesn’t sound too bad, for just winging it. Pretty sure mine won’t be anywhere near that impressive, I’ve nearly killed half of them just getting them into the soil.
I think they only got so tall cause I swapped the mh out for hps to early, some really long node spacing on the top half😅
I’ve been running my autos on 18/6 lately. Previously I ran 20/4, I get a similar yield and a slightly smaller bill.
18/6. Both plants and lights in my opinion need a rest.
Your the first i see besides myself to mention the legs on the fogdogs… I see it as well.
I originally started running autos to aid in keeping my grow up to temp, so it was 24/0 in the colder months and dropping to 18/6 when the flowering started and days grew warmer. Really dont see a difference.
Looks like I’m on team 24/0 by myself. Simplifies my environment in a Canadian basement. Usually have to dim my lights to keep the DLI in range but my plants have always been happy.
Same as GCBudz, I’ve run 18/6 many times. Not really seeing a quantifiable difference between the two, more just what fits your grow better.
Ok, sounds like the consensus is they can’t use 24 hours of light at full intensity, at least while flowering. Whether you reduce the hours or the lights, seems kinda 6 of one vs half a dozen of the other… I’ll probably go with the hours since the environment shouldn’t be too tough to control either way.
I’ll try out 24 hour days for a little while during the first weeks from seed, and if I start seeing them get tired before flower I’ll tone it down.
Read an article, made some sense, 12/12 is my experiment this winter.
Seed to harvest
Been running autos on 12/12 lights for 2 years tried all the rest it’s all the same,strong seeds will grow any light
Setting shit seeds won’t
I’m going back to 600w as soon as my new tents here, got it dimmed to 250 hanging in the bathroom rn for my seedlings, the 1000 is to much for em at their height. Just over a foot away and as high as it gets. I think they have another 4-6 weeks to go.
You’ll get better yields and potency if you move up to 18/6, but if it works for ya I ain’t gonna hate.