I think most LED manufacturers show PPFD maps at various heights above a 2-D flat plane, typically a table or the bottom of a tent. Since we live in a 3-D world dont we want to know what the PPFD is at the lowest distance above the canopy and also at the bud sites farthest from the light? Penetration matters right? Thats the only reason I can think of that they would map the PPFD at 6" above the canopy or is there something I am missing?
So what is the max PPFD a plant can take at the top? Depending on the light of course but if a plant can take 1350 PPFD at the top with the light 6 inches above it then at 18 inches below its getting 700-800 PPFD if should be some monster 18 inch long buds right? Anyway, I have always worried about the top of the canopy and it seems like the light at the bottom is equally important.
That's a good point. I could be completely wrong but in my opinion the buds that develop in the lower portions of the plant don't develop the same potency as the top buds that receive the most interest light. That is why I first started to Scrog, to expose more of the bud sites to the most intense light that I can. Any of the buds that develop below the main level of my canopy I generally use for edibles and save the top of the colas for smoking.
I agree and a SCROG does allow for the most even light distribution. With HIDs I know the range for Lux is between 40k & 80k so I would shoot for 60k at the top when maybe I should have gone for 80k so the lower buds would have gotten more light or stronger light and grown to a better potential. Now my head hurts, time to stop thinking and start drinking more