What Is VPD

Vapor Pressure Deficit (VPD) is the difference between the current amount of moisture in the air and the maximum amount of moisture the air can hold when it is fully saturated at a given temperature. This measurement is expressed in kilopascals (kPa) and reflects the dryness of the air relative to its temperature.

Why Does VPD Matter?

VPD is a crucial factor in plant growth, as it directly influences the rate of transpiration, nutrient uptake, and overall plant health. When VPD is within the ideal range, your plants can breathe easily and absorb nutrients efficiently.

However, incorrect VPD can negatively impact plant health. A VPD that is too high causes excessive water loss, leading to dehydration. Conversely, a VPD that is too low creates overly humid conditions, which can hinder the plants’ breathing, cause root rot, and encourage fungal growth.
The Ideal VPD of Every Growth Stage

For indoor growers, Leaf Vapor Pressure Deficit (LVPD) is more important than the room’s VPD. Due to transpiration, plant leaves are typically 3°F to 5°F cooler than the surrounding air, resulting in a slight difference between LVPD and the room’s VPD. This cooling effect, caused by foliar evaporation, makes LVPD a more accurate measure of conditions directly affecting plant growth.

To determine the optimal VPD, you should consider the plant’s growth stages. Here are the recommended Leaf Vapor Pressure Deficit (LVPD) levels for each stage of the plant's life cycle. Note that variations may occur between different strains.

Kit Includes:

• 1 x Gorilla Dual VPD Humidity + Dehumidifier Controller
• 1 x AlorAir Storm DP Yellow Dehumidifier
• 1 x Humidifier Large - Hydro Flow 50 Fogger
• 1 x AutoPot Tank - Flexi Tank 100L
• 1 x Multiflow Kool Tube 12.5mm id (16mm od) (per metre)
• 1 x Euro Plug Adaptor White 3A