Does anyone know if light plays a factor in grow time of autos. I use 300 watts true watts in a 2x2 tent. And it always takes a long time for flowering usually anywhere from 12 to 16 weeks in flower Huge bud but still takes a long time
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I don’t think it will make much of a difference in grow time or quality whether on 12 or 18…. Maybe a few days. The difference I believe will be in yield and 18 hrs is just going to produce more yield imo.
The intensity and quality of light will affect quality and yield. 300 watt is plenty of horse power for a 2x2. Most lights out there now have a decent spectrum and use the same diodes and drivers.
I use 20 hrs on and 4 off. Bigger buds than 18
Use 20 hours on 4 off
I do 16 hrs On 3 hrs Off
That’s some moon rock math there. 
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If I keep my light for 18 hrs, then it will blast, so I do 16 hrs on 3 hrs for cool down, then again 16 hrs
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Hey, it’s your light. You wanna be on Martian hourly calendar, rock it. Most of us use a 24 hour cycle, so things happen more or less the same time each day. So on plus off would equal twenty four, as in earth hours…
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@Duggie it’s hard to say because many things control the speed at which autos mature. Pot size, lighting, environment, and substrate.
Temperatures and light intensity play a big role though. They don’t like it hot and if it’s too warm (high 70’s or more) with high intensity (DLI over 60 with no c02) they’ll fox tail and keep flowering and fox tailing and flowering and usually flower for a good 4 weeks beyond normal estimates.
18/6-24/0 is the most efficient time. 18/6 takes a bit longer for finish but I notice a difference in terpenes with less light duration and intensity near the end. 24/0 will usually give you the fastest flower and bigger yields but they don’t seem to terp up as much. This is why many who grow autos split the difference and go 20/4.
I’d really need to know more to help you out though.
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Yes autos love 24/7 light it will get u best out of them
I like 18 hrs but I sdim two hours before lights out and leave dimmed for the first two hours when they way wake. I bake em for 14 hrs straight.
Generally that is about the time they will start to look tired under high intensity light… 14 hrs and dim it on either side.
The problem is most people don’t have the time to be adjusting their lights and timers only have so many settings. A full ac infinity set up and you could do it from your iPhone…. I may try it in a smaller tent with one of their new lights.
Plants will let you know when they are starting to get stressed… my experience is that is after about 14 hrs of high intensity.
If you’re going for quality and terpy flowers go with 18 hrs with cool lights off temps. Yield go with 20 but maybe at slightly less intensity. Or if your environment is cold go with 20 .
Even in photoperiod veg I limit high intensity light to the middle part of their day.
Indoor too many hot spots, no clouds, no moving lights… you need to give them a break when they ask for it or your flowers will not reach their potential.
So I don’t think it is as important which cycle you use. The most important is limiting high intensity hours… when the fans start dropping with the lights still on and they start looking like you just watered them…. Then turn the lights down. And give ‘em a break cause they’re getting stressed af.
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@laf6502 I have several off off brand lights I have tested over the years. One that I got last year but just started using recently has a built in timer. I have always been skeptical of built in timers because you never know what they will do if there is a power outage. So I fire up this light and it has dimmer switch so I put it on 100% and select the timer for 18/6 and it cuts off and cuts back on very dim. I was confused so I turned timer off and it went back to 100%. I messed with it and messed with it. Same thing happened. Pulled it out of the tent. Put up other lights hooked to a trusted timer. Contacted the manufacturer and told them they have quality issue and they tell me the light has daylight function that slowly ramps up intensity for first hour and ramps down for last hour. Nothing in the documents mentioned this and I told them they may want to add that in there somewhere. Lol.
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It would make sense… I don’t like them waking up to 100%. Also, At high intensity they are transpiring a lot so I do think it is better to cool them off an hour before lights off.
I have a question about lighting.
I’m doing my first autoflowering cycle and now it’s started to flower. the doubt is whether I use a PPFD of 800…900 or a DLI of 30. I’m doing 20/4 and if I use a PPFD of 700 the DLI goes to 50 something, if I use a DLI of 30 the PPFD stays at 400 .how do i calculate?
Usually in flower you want to aim for a ppfd of 700 - 1000, anything above that would be a waste unless you are using CO2. I wouldn’t worry about DLI so much as the sun I think provides a DLI of 60 and it is pretty much impossible indoors atm to recreate…I also don’t think it is going to affect your plants either way that much. I also wouldn’t recommend a 20/4 schedule for your plants as I have found no difference in yields and have done 24/0…20/4…19/5…and now all the time 18/6. But everyone is different so find your own ground! KISS!
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I am also going to tell you what is really going to drag out your start to finish time in general. It is going to depend on how healthy your plants are throughout the grow. The more you stress them the longer they will take…the less the faster they will finish. All depends on what you want your end result to be. What I mean by stress, it could be induced by training or by nutrient deficiency. Overwatering, underwatering, overfeeding, underfeeding, too much light, too little light, not enough air, too much air, lol…don’t overcomplicate things. KISS! Genetics come into play also, 2 many variables to worry about so don’t worry. Have fun unless you are planning on making it a profession.
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I understood. the plant has been signaling a lot of light, I ended up decreasing it a little, also in this fifth week of flowering I reduced the daylight hours to 19 hours. she still points out some deficiency in nutrients, as this is the fifth week of flowering, I decided not to load too much on the food. but the fan leaves are falling dry
It is not hard to reach DLI in any stage indoors based on the amount of time the lights are on with autos. The beauty of controlling the environment. You can achieve similar DLI in a 12hr or 18 hr grow by light intensity. Your yield and quality will most certainly be affected by DLI… Don’t kid yourself.
Obviously for an Autoflower, it is easier to reach the target DLI in flower as you can run lights 6+ hours more than a photo period.
Personally, my plants seem to love the 8-900 par range average in flower and can withstand that intensity for a full 18hrs… Although, I personally reduce intensity for for the first and last 2 hour periods of lights on (As there are some hotter spots in the translighting and at the tallest cola exceeding 1000-1100 par)
I think on a 12 hr grow you might want to see the hot spots pushing 1200+…(some people grow autos and photos together) On an 18-20 hr grow, 7-900 throughout the lights on period should be sufficient to achieve optimal DLI at a comfortable light and heat intensity for the plants.
There is differing opinion and data out there. Based on my research and my organic growing style, this works for me. Maybe in a hydro high density grow you’d want to crush them more with light. In a low/medium density grow I just don’t see the need to run the tent at pars higher than that.
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