Vapor Pressure Deficit Sensitivity

Vapor Pressure Deficit (VPD) sensitivity describes a plant's physiological response to the difference between air saturation and actual humidity in the cultivation environment. Cannabis cultivars vary significantly in their tolerance to high or low VPD conditions—some lineages thrive in drier air (high VPD), while others perform better in more humid conditions (low VPD). VPD sensitivity is influenced by leaf surface area, stomatal density, and root vigor, traits often inherited from parent genetics. Breeders working in controlled environments increasingly document VPD performance as part of strain phenotype characterization. Understanding a cultivar's VPD profile is essential for optimizing transpiration, nutrient uptake, and structural integrity across growth stages.

Breeders select for VPD tolerance when developing cultivars for specific climate zones or controlled-environment systems. Lines showing robust performance across varying humidity ranges are particularly valuable for commercial and regional cultivation programs.