I’m confused about vpd(vapor pressure deficit). It seems to be there are conflicting opinions out there. Attached I have two recommended charts for vpd. One is more general and states for a temp of 77 Fahrenheit/25 Celsius the ideal humidity is 70%-75%. On the other chart it states for plants in mid flower the ideal humidity for the same temperature is 45%-55%. That’s a huge difference! What is right?? Thank you.
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They both are.
Active veg requires a lot of humidity. As the plant flowers the humidity needs to be lower to prevent issues with bud rot.
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Top one looks nearly identical to the one I have, but it’s not the same. Mine doesn’t have farenheit temps listed
Edit… damn i hate not being able to expand images lol. After downloading, it looks like exact chart I have. That one is corrected for running leds. The other chart is probably set for running something like hps. Most led lights don’t have the ir that hps does, therefore lower leaf temperatures. In order to maximize transpiration different canopy temps and vpd are required.
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the bottom chart is for high growth plants,
the top chart has been relabeled for cannabis use,
that one will get u were u want to be.!!
if u keep looking u will find many different VPD charts, use them loosely, let your plants tell u what they want.!
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I appreciate your response. So the top chart (the one with mid and late flower on it) is the one you use and it’s specifically for led? Also what’s “ir”?
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That was my understanding when i downloaded it, specifically for white leds. Ir is infrared light.
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