Plants absorb CO2 and evaporate water into the atmosphere via the leaf stomata. High VPD values will lead to tremendous stress and closing of the stomata resulting in less CO2 uptake
VPD and HPS
Although your light source is not a direct factor in your VPD equation, it can affect your reaction to correct your VPD value when its off….
Where under HPS you usually will experience high VPD you will need to use a humidifier to correct that in the daytime.
VPD and LED
Under LED it’s more likely that you need a de-humidifier to boost up the evaporation rate and raise the temperature at night to maintain the correct VPD and prevent mould.
We have created a VPD monitoring device unlike any other.
The device consists of a display unit and a “sensor module” which should be placed above the canopy.
True VPD means that the sensor has a built-in leaf temperature sensor. No leaf temperature means no true VPD! Now you can finally monitor the true VPD, ambient & leaf temperature, humidity, and dew point; all your plants’ vital signs.