Lighting COB Watts- per plant or per square foot?

[BigSm0]

About 12 days of 4x COB (aprox 240W actual) and no signs whatsoever of burn or bleaching, no fox-tailing.

I think it may be partly strain, but I am guessing that mostly it is up to timing- once they are in full bloom, the extra watts are beneficial, but in early growth too much can stunt them.

Early on in veg and the beginning of flower you may not see any stress but come mid to late flower is when it comes on strong. As far as wattage goes and wattage per square foot I run below 20 watts per square foot on all my grows. Usually 15 watts per square foot, my autos are generally one cob per plant and they take up at least a 2x2 each. Autos and photos are different and efficient cobs vs hps is different.

 

[VitaMan]

Early on in veg and the beginning of flower you may not see any stress but come mid to late flower is when it comes on strong. As far as wattage goes and wattage per square foot I run below 20 watts per square foot on all my grows. Usually 15 watts per square foot, my autos are generally one cob per plant and they take up at least a 2x2 each. Autos and photos are different and efficient cobs vs hps is different.

Thanks BigSm0.
16 days of 4x60 watt and still no signs of stress on the mid-late flowering Blue Cheese plants, but I might be over-lighting that small space. The IP CBD is in very early flower and showing slight burn on the leaf tips.

I wish I could light 2 cobs, but this unit lets me light 1, 4, or 5 COBs. This is where your units would have been better....

 

[ReNN]

Should be fairly easy to rework the fixture to run the combinations of lights you wanted.

Sent from my ONEPLUS A6003 using Tapatalk

 

[Black Sail]

Burning and bleaching from LED's is usually caused by the diodes being run too hard, or having too tight a lense on it. This will give you hotspots when you run the light close enough to the canopy to get a decent PPF. It's not the LED's themselves, it's the way they're being run. I've run cxb3590's 8"-10" away from my canopy at 50W (<50% max power) without bleaching or burning, and I've run The Cannon 12"-14" away from canopy at 240W(<50% max power) without bleaching or burning. This is towards the end of flower, without any reflectors or lenses.

Some companies will put a tight lens on a weak diode so they can rep. a high PPFD over a tiny area. This will give you hotspots too, bleaches and burns along with it.

Watts per plant isn't a good measurement in my opinion, because what's a plant? Is it a 6 foot tall Jumanji monster or a 1 foot tall clone to flower in a Sea of Green? Watts per square foot isn't perfect either, but assuming you're dealing with high quality COBs then 37.5 watts per square foot is a tried and true method for maxing out your space.

I'm an organic grower so I like to have 4-6 big ass trees per 4' x 4' with 600 watts of COBs overhead. If you have enough power in your lighting you can get a full canopy with a good 2'-3' depth and get major yields. People get great results with 9-12 smaller plants in that space though...

My company's light is 240W, (my AFN Forum), and I'd say two big plants or three medium plants is perfect:smoking:

 

[Black Sail]

I think 55w per plant is enough..

Depends on what you mean by plant though... Big ol' bush, or clone to flower popsicle in a sea of green? Watts per square foot isn't perfect but its a wayyy better metric because watts per plant adds in all the uncertainty and ambiguity of not knowing what someone means when they say "a plant".