Vapor Pressure Deficit Vpd

Vapor Pressure Deficit (VPD) is an environmental measurement—not a strain trait—that describes the difference between the amount of moisture the air can hold versus the amount it actually contains. In cannabis cultivation, VPD is a key parameter breeders and growers monitor because it influences transpiration rates, nutrient uptake, and plant development. Different cultivars respond variably to VPD ranges; some lineages have been selected for performance in high-VPD environments while others thrive in low-VPD conditions. Understanding a strain's VPD preferences requires observing phenotypic expression across controlled environments rather than relying on genetics alone, since the same cultivar may exhibit different characteristics under different atmospheric conditions.

Breeders working in regulated or controlled-environment agriculture often track how parent lines perform across specific VPD ranges, selecting for stability and vigor in target conditions. This data informs decisions about which crosses may suit indoor, outdoor, or hybrid production systems where VPD varies significantly.