Environment
Cannabis VPD Chart by Growth Stage
Vapor Pressure Deficit (VPD) is the single best metric for tuning your environment. Hit the right window and your plants transpire freely, eat more, and grow faster.
| Stage | Target VPD | Temp | RH |
|---|---|---|---|
| Clone / Seedling | 0.4 – 0.8 kPa | 75–80°F | 70–80% |
| Early Veg | 0.8 – 1.1 kPa | 75–82°F | 60–70% |
| Late Veg | 1.0 – 1.3 kPa | 75–82°F | 55–65% |
| Early Flower | 1.0 – 1.4 kPa | 73–80°F | 50–60% |
| Mid Flower | 1.2 – 1.5 kPa | 72–78°F | 45–55% |
| Late Flower / Ripen | 1.4 – 1.6 kPa | 68–75°F | 40–50% |
Clone / Seedling
0.4 – 0.8 kPa
Roots are still developing. Keep humidity high so leaves don't pull water faster than roots can replace it.
Early Veg
0.8 – 1.1 kPa
Plants are establishing structure. Slightly drier air encourages stronger root growth.
Late Veg
1.0 – 1.3 kPa
Dial humidity down gradually. Plants should be transpiring strongly.
Early Flower
1.0 – 1.4 kPa
Stretch phase. Plants want similar VPD to late veg, just slightly cooler.
Mid Flower
1.2 – 1.5 kPa
Buds are bulking. Lower RH helps prevent mold; VPD stays moderate.
Late Flower / Ripen
1.4 – 1.6 kPa
Push terpenes and color. Cooler nights, lower RH, but watch for stress at the high end.
Want a printable VPD chart?
PDF cheat sheet you can hang in the grow room.