So you adjust the plant height to be wherever you need to be to be at 2 degrees leaf temp difference, and take whatever par number you have at that point? And in theory you could increase par (and thus leaf temperature) on the ones 3 degree below cuz they can come up a degree to ideal?
This is kind of like using the light more as a temperature control device isn’t it?
Another question: the difference between 3 degrees below or exactly at 2 where you want or 1 below air temp - what kind of effects in the plant are we talking about with that small of a difference? Besides that it tells you whether to raise or lower a plant? How bad would it be if you were constantly at 3 degrees below, for example? Vs a plant that was kept at 2 degrees below the whole time?
I have never actually tried to run a single plant warmer, but I have run a single plant cooler, which puts it farther away from the light its whole life. It is a lesser plant all round as you would expect.
I have never used PPFD as a guide before, always VPD and leaf temp, so you teaching me PPFD is also a factor now too, and I am finding that by using VPD to determine light intensity I am ending up right about where you said I would want my PPFD.
Here is an interesting observation. The tallest pheno is closest to the light and at 1030 PPFD and could handle 1 degree more of light, the 2 mid height phenos are at 950 PPFD and could handle 1 degree more light, shortest pheno is at 850 PPFD and can't handle any more light.
It may be coincidence, but if they were all on the floor then the tallest pheno would be handling the most PPFD properly, the 2 middle height ones would be handling the lesser amount of PPFD because they are shorter properly, and the shortest pheno which would be farthest from the light and at the lowest PPFD, would be handling the lowest PPFD properly.
In my tent right now, the taller the pheno the more light it can handle to get to the 2 degree differential. Its like height amongst phenos dictates the phenos ability to handle light or, the amount of PPFD a plant can handle dictates its phenotypical expression.
Either tall phenos can handle more light, or phenos that can handle more light grow taller to get it.
Pretty cool. I must watch this over a few grows. Adding PPFD measurements to the mix is very educational. Thanks
@Jon 
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Later today I will adjust all heights and then get my leaf temps back to a uniform 2 degree differential. My canopy won't be even in height, but it will be even by leaf temps, then we can watch and see which plants do what.
I'm pretty sure I need to strip the mulch off too.
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