LED lighting and Hang Height / Bud Quality

im 2 Days away from starting week 5 of flower into my 3rd grow ever.

the other two grows I struggled with airy buds the first time and the plant went herm in late flower the 2nd grow, also with airy budz… possibly due to heat stress from hanging the lights too low idk.

Growing a completely different strain now and wanted to know what the recommended distance is to hang an LED grow light and where that distance is measured from?
to avoid heat stress and still provide enough light to get those dense dispensary quality budz

Is hanging the lights at different heights from each other a problem?

Current set up:
4x4 grow tent
69-77F/52-60%humidity

I have have a 300W full spectrum LED 24x24 square hanging centered over 2/3 of the the plant.
It is 9inches above the highest point (cola tip) on the plant, 12-13 inches above the rest of the cola tips and 22-24 inches above the canopy, leaves and stuff (base of the colas)

Also have a 200 W full spectrum LED 24x13 over the other 1/3 of the plant. this one is hanging lower cuz that part of the plant is not as tall. The distance above is the same, 12-13 over cola tips and 22-24onches above canopy.

Have a third light just off in the corner pointed at the center of the plant…its a 35W red LED spot light.





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It’s whatever your plants, lights and you can handle.

What I am seeing…
single stem main colas, significant difference between it and the rest of the plant. PPFD drops dramatically the further the plant is from the light. This results in poor bud quality for the lower stuff.

Learn to
Topping
LST
maybe scrog
It would have helped to supercrop / bend the main stems to decrease height.

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Man, that’s tough to answer, but my rule of thumb is 24” for veg, and 15” for flower. I use an hlg 350r. I use my dimmer from there to get the intensity I think is correct for the stage I’m in.

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I use the Photon app on my phone. It’s free I had to pay $5.99 one time fee for the LED Full Spectrum function. Tape a piece of paper over the photo lens on the front of your phone as a filter and it gives you Ppfd DLI illumination

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Thanks for sharing that app, helps a lot.

At what point on the plant do you take fhe ppfd measurement from?

The bud site closest to the light?….Getting 2200 ppfd there

The lowest bud sites? Im at 600-900 ppfd there

“Law of the Minimums”, controls the plant (and all life).

Plants are solar engineers and frugal. No wasted energy on low light living conditions.
The answer is, the plant will respond to more hours, more lights, or more love, your selection.
Good growing to you.

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@neelnkp




This is why I tie down my plants with Low Stress Training so I can keep my tops even. I normally check for their DLI air was suggested to me but I believe DLI I’m going to search the DLI table now

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@neelnkp just tap on the “where did I put that graph” link and it’ll take you to the thread. It’s the top graph. If you go to the top of the forum page hit the search icon type in DLI chart and hundreds of threads will pop up do some reading and find what works best for you. Best of luck growmie!!! :+1:t2::+1:t2:

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I added the DLI formula to the basic graph.

The easy way to convert PPFD to DLI is

PPFD X light hours X.0036
.0036 is a constant

I think many of us run higher PPFD / DLI at beginning of flower than shown.

This one is what @Nicky likes

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I had the same problem last grow with my led, i switched to 600watt hps an my buds got alot denser. But i wound prolly bring my lights as clise as possible without burning them.

Really week 5 is when they start putting on weight, they will mist likly start getting denser as time goes on. They look really good to me now tho.

All lights are different in quality and how much usable light they out out. Some lights require 12 inch, some 18, 24, and more even. I have the growers choice and can easily put it 6 inches away running at 100 percent . I am using co2 though .
But I would first contact your lights manufacturer and ask them what they suggest for hanging heights. Then I would invest in a par meter. Photobio phantom is a good one and reasonably priced. Then I would save 2 charts and try to follow them as best as you can. First being the dli chart , then the vpd chart on dimluxlighting website. That will cover everything other than what you do for nutes. I personally tried a couple different ones and different soils on my first grow that I’m about to chop next week. I have found that the all organic is so much easier and better . Next grow will be sohum living soil with greengro pride lands organic fertilizers . :+1:
Here’s where the instructions above got me .





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