Hello all, the VPD is a critical measurement that helps the cultivator achieve stomata control with higher brix levels. Your plants will transpire at lights out if the VPD is not correct.Transpiration will cause a host of negative issues. Water can form on the leaves and that will cause yellowing of leaves and a host of other issues such as bud rot ( Botrytis Cenera) I am enclosing some links for your learning pleasure.
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