Low Humidity / High VPD Stress

Leaves cup and curl upward as the plant tries to reduce surface area and limit moisture loss. Plants in very dry air (below 40% RH) or with high VPD will show this first in the upper canopy.

What usually causes it

• Relative humidity below 40%
• High temperature combined with low humidity (high VPD)
• Insufficient humidification in dry climates

Related product categories

• Climate & Ventilation
• Humidifiers & Dehumidifiers

Terms worth knowing

• VPD (Vapour Pressure Deficit)

Walk the questions if you are not sure this is the match. The notes above are the same ones the tool ends on.