Mastering Measurements of VPD

Special Advertising Section - Special Report: Humidity and Climate Control

November 22, 2021

There is a growing understanding around monitored levels of humidity results in thriving plants, and gone are the days of keeping grow rooms as dry as possible to avoid mold and mildew.

Cultivators benefit from applying vapor pressure deficit, or VPD, in grow rooms because it enables them to encourage plant growth and optimize the environment by monitoring the relationship between plant transpiration, humidity, and temperature.

To understand VPD, it is first important to grasp transpiration, which is the biological process where moisture travels from plant roots to leaf pores, where it evaporates into the air as water vapor. In hot and dry conditions, plants transpire more, just as humans sweat in the heat, resulting in increased water use and watering requirements.

VPD correlates directly to plant transpiration rates, so by controlling VPD, growers can control how quickly moisture and nutrients travel through plants. Increased VPD results in increased water and nutrient uptake through plant roots, which, at the appropriate life stage, boosts plant growth.