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Wisconsin

SO Lets start with PPFD, in simple terms this is a measure of light that is usable to plants. Now we can take a PPFD reading along with the hours our grow light is on, and get DLI (Daily Light Integral) Which is a measure of how much light a plant receives over a 24 hour peroid. SO we can run a higher PPFD for 12 hours and get the same DLI as running a lower PPFD for 18 hours...........................

2/19/2024 10:23:36 AM

Wisconsin

SO I got a new grow tent and a new grow light. I cranked the grow light to run about 600 ppfd for 18 hours about 39 DLI and boy were the plants pissed. I went down to 450 PPFD for a bout a 29 DLI and the plants were better but I had to turn it down to around 320 PPFD for around a 21 DLI and they looked ok...........

2/19/2024 10:26:13 AM

Wisconsin

SO it got my wondering what was my last grow light running at? When I checked it I was surprised to see that it was around 600 PPFD but I had only ran it from 12 hours a Day which gave me around a 26 DLI.

2/19/2024 10:28:16 AM

Wisconsin

I am currently running a test where my new light is just under 600 PPFD for 12 hours to give me the 26 DLY that worked well before....

2/19/2024 10:29:36 AM

Wisconsin

SO anyways I'm curious if anyone has any data on what readings have worked for them in the past.

Please note the optimum of these readings can changed, based on water, nutrients, temp and CO2 level (im not supplimenting CO2)

2/19/2024 10:31:00 AM

Beaver WV

what kind of meter do you have and where to purchase one? Amazon?

2/19/2024 2:49:45 PM

Wisconsin

Theres an app you can get for free on your Phone called photone, but it should be calibrated with a meter that is good. I think an Apogee meter would be a good one, I'm thinking about getting one and we could calibrate many peoples phones at seminars and then we can compare to each other. Having said that my "meter" might be off a little.

2/19/2024 2:57:02 PM

Beaver WV

Sounds good and thx. Will see if Amazon has them

2/19/2024 3:00:09 PM

Walla Walla Wa.

Yes Amazon has them for about 603.00

2/19/2024 5:13:00 PM

Westmoreland, KS

I've been testing with different lights at different heights...I'll use my photone app tonight and let you know what the reading is at plant lvl...my starts have been great this year I was thinking it was the height of the light but we'll try to get more scientific with it.

2/19/2024 5:17:45 PM

Chihuahua Mexico

I also have the question here. although the question is little different. Does the same work with the sun during the season? to know what percentage of shade mesh one can put?

2/19/2024 5:42:32 PM

Grittyville, WA

I dont know much about the technical stuff, but ultimately plants are designed for normal sunlight, and a normal photo period... test your meter outdoors and see what it says? Thats your baseline:)

2/19/2024 7:43:10 PM

Westmoreland, KS

I was around 300 at 18 hours and 20 dli

2/19/2024 9:37:49 PM

Lloydminster/AB

I haven’t ran the experiment yet but I had mine at over 600 Ppfd. Pumpkins seemed ok but my tomatoes fried. I changed to 18 hours a day and that helped the tomatoes. My peppers seemed to deal with the light ok. Ive added some distance and I think I should be around 450 ppfd now.

2/21/2024 10:23:27 PM

Fair Oaks, CA

I tried the Photone light app but it's $80 in order to read Full Spectrum LEDs and requires a diffuser to add on to your phone.

I found the Lux-525 app to work well on my iphone, no diffuser required either.

2/26/2024 7:01:25 PM

Grittyville, WA

Did you gain the wisdom you were seeking? The WR is back to the USA, and back to the great outdoors... Just missing one last thing, we're past due for someone with a beard to be #1?

2/27/2024 6:32:22 PM

Roseville CA

Hey Mike ive used Photone for a few years and I have really dialed in the PPFD. Basically, I've used the same grow light, and it goes to 100%, so I use the dimming + height of the light to adjust the PPDF. What I do, is as the seedlings emerge I start the PPFD at 320, and have it on for like the daylight hours so around 12-16 hours, depending on when I wake up. Then, around every day, I slowly increase the PPFD by around 50. What it does, is help the plants slowly get used to the sun because the sunny day is like 2200-2400 PPFD, so in like a few days if I can get the plants to get comfy with like 450-500 PPFD before I start hardening them to go outside, that helps the transition to the outdoors. (I found this my experimenting on seedlings before I planted my real ones.)

3/8/2024 9:13:11 AM