Ideal VPD Ranges by Growth Stage

• Seedlings: 0.4 – 0.8 kPa

• Vegetative Stage: 0.8 – 1.2 kPa

• Flowering Stage: 1.2 – 1.6 kPa

Temperature vs Humidity Relationship

• High temperature + low humidity → High VPD

• Low temperature + high humidity → Low VPD

Balance both for optimal plant growth.

Visual Chart 

Common Grower Mistakes

• Ignoring VPD completely

• Using fixed humidity values

• Not adjusting for plant stage

• Poor ventilation