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ConstantGreen
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re: PPFD Measurements & Analysis for LEDs
My question is... say the maximum photosynthetic rate for cannabis is 1500 PPFD with CO2. I'm pretty sure that study was done on single fan leaves, not whole plants. So does every leaf on the plant from top to bottom need to be radiated at 1500 PPFD to achieve maximum results? If so, penetration would be pretty important, to make sure those bottom branches are getting just as much light as the top branches. But it seems almost impossible to max out that way, you would need lights all around the sides and within the canopy.
I've had canopies so dense... there's no way light from the top can squeeze through more than 6 inches of dense foliage. So that raises the question of how deep should a packed canopy be. Or whether it should even be flat and dense.
Hello and welcome to 420 Mag! Replied to your questions individually in the quote.Hey folks, new here, got a question,
I know Lux and lumans and LEDs mean nothing in measuring sense, but what if,
You have 1000 par, but 500 lux? Does it matter that the intensity is so weak? as per Lux measurement? Ive seen Neils vidoes (BlackDiamond) and he talks about 60,000 lux, but at 60,000 lux, what if Par is 1400? For Lux not meaning much, why does a LED light builder talk so much about it?
Not sure why he talks about lux but it's not as precise as PAR for measuring grow light quality. Lux is a measurement of light visible to the human eye. PAR is a more specific range(400-700nm) within the visible light spectrum that plants use to grow. A lower or higher lux value doesn't matter, it's PAR that counts.
600 par but 100 lux, would mean what? What could one expect from these hypothetical numbers? Does intensity ( lux) mean penetration force?
That doesn't mean anything exactly, but it probably means the light source is deep red or deep blue. Reds and blues are harder for humans to see so they aren't worth many lux, but plants love red and blue light so it's worth a lot of PAR to them. Humans see green light the brightest, so green is worth the most lux, but plants do not absorb green light so well. So a green LED might give more lux than PAR. Lux alone doesn't tell you anything about penetration unless you measure it at multiple heights.
What if all flowers are on the surface, and need little penetration because of it?
Having all flowers on the surface in a flat canopy would be ideal. It limits your needs for penetration. But this is something I don't quite understand and want to learn more about too.
Brain picking, since par and Lux are worlds apart in the LED Land.
Thanks,
My question is... say the maximum photosynthetic rate for cannabis is 1500 PPFD with CO2. I'm pretty sure that study was done on single fan leaves, not whole plants. So does every leaf on the plant from top to bottom need to be radiated at 1500 PPFD to achieve maximum results? If so, penetration would be pretty important, to make sure those bottom branches are getting just as much light as the top branches. But it seems almost impossible to max out that way, you would need lights all around the sides and within the canopy.
I've had canopies so dense... there's no way light from the top can squeeze through more than 6 inches of dense foliage. So that raises the question of how deep should a packed canopy be. Or whether it should even be flat and dense.