Ideal Relative Humidity for Greenhouses
The ideal relative humidity for greenhouses is generally between 50% to 70%.
What happens if humidity is too high?
When greenhouse humidity exceeds 70-80%, condensation forms on plant leaves, creating the perfect breeding ground for fungal diseases like Botrytis (gray mold) and powdery mildew. It also reduces the plant's ability to transpire, which limits nutrient uptake.
What happens if humidity is too low?
If the relative humidity drops below 50%, plants transpire too quickly, losing more water than they can absorb. This leads to wilting, stunted growth, and crispy leaf edges.
Frequently Asked Questions
- How can I lower humidity in my greenhouse?
- The most effective methods are increasing ventilation (opening vents and using exhaust fans), watering plants early in the day so the surface dries before nightfall, and using a commercial dehumidifier.
- Does temperature affect greenhouse humidity?
- Yes. Warm air holds more moisture than cold air. As the temperature drops at night in a greenhouse, the relative humidity spikes, often leading to condensation on the walls and plants.