VPD Chart

VPD chart and calculator

VPD leaf 1.23 kPa

Leaf Temp under Dew Point: Danger Zone (Plant Disease)
VPD under 0.4 kPa: Danger Zone (Under Transpiration)
VPD from 0.4 to 0.8 kPa: Early Veg / Propagation (Low Transpiration)
VPD from 0.8 to 1.2 kPa: Late Veg / Early Flower (Healthy Transpiration)
VPD from 1.2 to 1.6 kPa: Mid / Late Flower (High Transpiration)
VPD over 1.6 kPa: Danger Zone (Over Transpiration)
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How to use the VPD chart

  1. Set the air RH and the air temperature with the sliders. Or click a cell on the chart (on a phone, tap it).
  2. Set the leaf temperature. If you do not measure it, set it 2 °C (3.6 °F) lower than the air temperature. To keep this difference when you change the air temperature, select “Link temperatures”.
  3. Read the leaf VPD above the sliders. The color of the value is the color of its zone on the chart.
  4. Find the point on the chart: the dashed lines cross at the air RH and the air temperature.
  5. Compare the point with the zones. The legend gives the VPD range of each color.
  6. To set a target VPD, right-click a cell and select “Set target”. On a phone, touch and hold the cell. Then select “Show me how”.
  7. To change the crop or the temperature unit, select “Chart settings” (the gear button on the chart).