A dehumidification system is a more cost-effective way to control humidity than venting outside air, as the highest humidity points inside the greenhouse often correspond with the lowest outside temperatures, leading to higher heating costs to maintain greenhouse temperature.
The fall and spring are times when humidity related diseases usually peak in greenhouses. Sunny days increase the transpiration of moisture from leaf surfaces and evaporation from soil and the warm air holds the moisture in the vapor form.
At night as the air cools to the dew point, condensation occurs and water droplets are formed on cooler surfaces such as the leaves and glazing. This moisture promotes the germination of fungal pathogen spores such as Botrytis and powdery mildew.
The key to successfully suppressing diseases is to keep the plant canopy dry, especially from dusk to dawn. This can be accomplished with dehumidification systems. Humidity management is a valuable tool to prevent diseases and save on energy costs in greenhouses.
