Ideal Lighting Cycle for Autos?

Starjunstarted grow question 10mo ago

On my first grow and I have been doing 24/7 with the lights (auto flowers) but it seems like that is not ideal based on other people’s growing experience. It seems like most people prefer 18/6 or 20/4 for their lighting cycles, is this true?

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BudMunchiesanswered grow question 10mo ago

You’re right—although autoflowering cannabis plants can be grown under 24 hours of continuous light (24/0), it’s generally not considered ideal. Most growers have found that autoflowers perform best under a lighting schedule of either 18 hours of light followed by 6 hours of darkness (18/6) or 20 hours of light followed by 4 hours of darkness (20/4). Cannabis plants, even autoflowers, benefit from having some darkness each day. During these dark periods, plants perform important metabolic processes that support overall growth and health, including root development and nutrient uptake. Without a dark cycle, plants may experience unnecessary stress, slower growth, and reduced overall vigor. A lighting schedule like 18/6 or 20/4 offers a good balance—maximizing growth with ample photosynthesis during the day, while also allowing essential recovery and metabolic processes during the short nighttime period. Between these two options, many growers prefer 20/4 for autoflowers to squeeze in a bit more growth potential without significantly sacrificing rest. If you’re currently running 24/0, consider transitioning to either 20/4 or 18/6. This often results in healthier, more vigorous plants, and ultimately, better yields and quality. Hope this helps your grow buddy!

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00110001001001111Oanswered grow question 10mo ago

Proper dli with 'enough' darkness. More hours of light does not necessarily mean more yield. Your environment creates a ceiling for photosynthesis, which limits how much DLI you can provide each day without damaging the plant. 18/6? 16/8? irrelevant if you are giving the same DLI. I wouldn't go more than 18hours/day of light unless your light is incredibly underpowered and the boost to DLI outweighs the lack of a dark cycle. "Dark cycle processes" can and do occur in the light, so 24/0 can work okay but not ideal. Also, irrelevant whether you are growing autoflowers or photoperiods outside of a long enough dark cycle causing flower phase for photoperiods. Both can handle the same levels of DLI. It's just a subspecies or variant and not that much different otherwise. I feed autos the same exact way i feed photos. I provide light the same exact way with same power and distance hung. they react the same way, grow the same way etc etc. I love the fact that people think they are faster, and the businesses that gladly take advantage of that misunderstanding, lol. 14-16 weeks for a small plant isn't faster.

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ATLien415answered grow question 10mo ago

m0use really expounded on the topic well, I concur with the DLI approach (in fact I have some diaries that take the DLI approach to light delivery and take it to extremes, like 8 hours on 16 hours off; the DLI approach has never been wrong yet). theoretically if you could have the plant ready to receive the DLI and could safely deliver the entire day's worth of light in a single second, then you'd be growing top shelf gas god level fuego with a 23 hour 59 minute and 59 second night cycle; this same exact math is the reason why 9/10 homegrowers (in a wildly generous estimate) using CO2 are wasting their time and money we often forget that the plant conducts activities at night... a 24 hour light cycle with no break is always wrong. the plant will try to establish a rhythm and will be stressed; this is also why pure darkness at the end of the grow is 100% grow-bro-science (the plant will still behave according to the established cadence and nutrient transport will still occur in the would-have-been daytime as if during the day, much like other species and their circadian rhythm) IME as long as your lights math right, the best flowers I grow are with the longest night periods

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Hashyanswered grow question 10mo ago

I'd say 1st 2 weeks go 20/4 then 18/6 for the rest of its life. Autos like most plants still need a rest period.

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Eggie420answered grow question 10mo ago

Yes the most standard Cycle is 18/6 but also 20/4 is possible.

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Ninjabudsanswered grow question 10mo ago

20/4 works good if the plants get stressed go to a 18/6

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