PAR vs. DLI for Autos

Better to have more than needed, you never know if you’ll ever decide to go or try photoperiod strains. And you can sometimes, depending on variant run into overheating and your crisping up the top leaves wondering what da heck is going on, so it helps to raise the lighting. With that Xtra power your not losing anything because of it. I’ve had strains that don’t care if your 12 inches above them and others that weren’t happy unless the lighting was 18-24 inches away. I’m kinda partial to the bar style lighting as it seems the heat escapes a lot easier with the added air flow between the bars. Im currently using two Mars Hydro 1000 in my 4x2 tent which honestly have been kicking ass to my surprise. I’m dam near tempted to grab a Hydro 3200 though. Just because, not that I need it. Wife thinks I’m nuts, have a nice bar fixture (Growers Choice) and 2 Mars Hydro 2000 just sitting in the garage collecting dust. But I’m all into my 4x2 at the moment. First World Problems…lol.

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This is the chart from the same source for autos. Higher number is for people using CO2, the lower ones are for the rest of us. It’s a good reference, but definitely not exact. Every grow with every strain is different. I’m growing zkittlez autos right now (18/6) and they don’t like the light closer than 24" or the DLI over 40. Tried to up the light again today (lowered to 21", even turned it down a notch later) and they still don’t like it at four weeks into flower. HLG 350R at 24" and 7/9 intensity seems to be the sweet spot for them. They look good and are making steady progress there so I’ll probably raise the light and turn it back up before bed.

The main thing is reading your plants. If they look happy and are growing well then leave your setup as it is. These charts are basically a starting point for noobs like me. Lol. If your plants seem to like more or less light then that’s what you give them.

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Hi. New here. Great thread.
I’ve got some autos in a 4 by 2 with a grow light science progrow 320 light. Might be overkill but here is my question

If I’m looking to hit my max dli without co2 on 18 hrs of light, I can turn this light to 60 percent and still get over 600 ppfd This would really lower power cost and help with temps etc when it’s really hot here. Per the numbers, I’m maxed at useable dli at the 60 percent power level

Is there anything to gain at a higher ppfd and thus higher dli or am I better off staying near the max daily light integrity but not above.

I am in supersoil and the plants are very young. If I use less power I’m able to cool a few degrees lower-from 77 to 73 or 74 (at hottest part of day)

I know I’ll have to find optimal via trial and error but I plan on more of a perpetual grow so looking for best scenario for all stages.

Thx

I’m in the same boat. 320 watts but only need 60 percent to max out dli.

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I think your good where your at, If you wanted to experiment with more DLI then go 24 hours. I have a 320 watt light in my 4x2 as well, love the efficiency of that unit. If you want to try Photos (like I am right now) then you have the light for it. You might think the 320 is overkill but the par map has to be the best you can find for your tent. Corner to corner even lighting is key to a high yield in my opinion. Hard to find that in lower watt lighting systems. Don’t ever let someone tell you you have to much lighting.

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Yeah. If I can ask you a question…did you run the 320 light on autos? If so, did you run the light at 100 percent or less. I’m 5 days into the seedlings and have it at 60 percent power and 20 inches from the plants. The plants seem to be doing well.

You are right about the coverage of this light via the par map. Can’t be beat. Im going to work on last to try to cover the canopy as evenly as possible. Probably won’t do a screen as I’ll do a perpetual grow starting a new plant for every plant that is within a few weeks of maturity.

If my numbers are correct I should be max dli at 18 hours s at 60 percent (no co2) and can probably stay here raising the light as the plants grow. For smaller plants I will use plant stands as needed. Oh well we will see. Running a supersoil with natures living soil, 1/3 earth, perilte, and coco each. Covered the super soil with coco cause that stuff stinks bad. Also started seeds in same soil less nutrients (4 inch peat pots) 3 gallon fabric pots and temps about 77. 70 at lights off. Ph tap water to 6.2 or distilled. Dropping ph now with white vinegar till my stuff arrives. Coco was buffered w cal mag but my water profile here is pretty good.

Oh and always trying to resist the temptation to overwater. Got 4 started.

Blueberry auto, purple punch, forbidden Runtz and grapefruit auto. Next up mimosa cake.

What ILGM seeds do you use? Am mainly an indica guy.

Next thinking of grabbing a mix pack of berry autos. Thanks for the reply.

I’ve only tried the Pineapple Express photos from ILGM. Little expensive so I now grab my beans mostly from Seedsman. I will say the ILGM Pineapple Express was some really good smoke. Flavor, tons of flavor.

My last 2 autos, White Widow and Lemon Haze were grown under two Mars Hydro 1000’s and I wish I had my new light up when those were going. It arrived 2 weeks before I harvested, and I noticed immediately what could’ve been had I done the whole grow with the new light. No shadows on the sides anymore. I use to be a photographer so I notice shadows easy. And with this new light they were none existent. I got 2 jars out of it so all good.

Wow, 60 percent… seems a little high. I’m at about 20 inches and am running it at 40% for a PAR of 300 for my photos I just started. We might have the same light, I got the Hydra 3200 I mentioned above here.

I kinda did the same as you with the soil, I have a thread here about it. My grow

It’s tough for me to help growers that use a super soil and then grow with a synthetic bottled style. With bottled nutes you need a 20 to 30 % runoff and there goes all the super you added to the soil, just doesn’t make sense to me…ok done with my little rant.

Yeah I get ya. By the way. I’m not using bottled nutrients to fert. I just used cal mag to buffer the coco for the first time. This is just what I’ve read to do. Might be overkill. I am at a point going to be looking into some good flower nutrients for this supersoil and prefer to stay with dry stuff.

I know that the there is a natures own super soil flower blend for ferts but I’m nervous to top dress with their stuff cause damn it smells. I won’t need this for about a month but if you have any ideas I’d like to know.

As an update the plants are liking the 60 percent setting at 20 inches. Probably time to water tonight!!

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Perfect, I just had to use some Cal mag the other day, It’s the LED lighting, because we use it we need to cal mag the ladies sometimes, some strains cruise with no problems, other need it like a bad meth habit.

Some of that stuff smells really bad is right, but after a week it’s gone. Neem Seed Meal for example, wreeks like the devil’s ass… :weary:

and yeah if that 60% is working continue on, autos can handle it. Ruderales strains sit in 18 hours of light in nature so add as much as you can give it.

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Yep. I figure I’ll push the upper end of sanity with the DLI till the ladies tell me to back off.
Thx

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That’s what I’m doing. No problems yet

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Three weeks into flowering

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Damn. Nice

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As for this question, the answer was already given by one of our community members and you can read all about it at this thread about how to start using DLI for indoor growing.

That said, if you want to read more about the optimal lighting, please take a look at our guide about maintaining optimal lighting for cannabis plants.

@Logan.ILGM thanks!


Hey guys! Here is the chart I use for DLI. MAKES EVERYTHING SIMPLE. AND YES THERE IS A DIFFERENT RANGE FOR AUTOS COMPARED TO PHOTOS.
ALSO, MAKE SURE YOU PAY ATTENTION TO THE DIFFERENCES BETWEEN THE NUMBER OF DLI WITH CO2 VERSUS WITH NO CO2

That chart isn’t for autos. This one is. And par for autos should not be over 700 max imo.

I use the same chart. With my autos I target 45 dli over 20 hours.

I use PAR readings and run lights 18/6. Not a expert but plants are doing great.
300 seedlings
600 veg
900 flowers

Thanks to all who posted information. First time grower, and using the advice here, it kind of took the guess work out of my lighting. Lights went off in my head, knowing I am on a 20 hour lights on (autoflower) schedule, let me back off the intensity I was running.