Humidity management is an important part of integrated pest management. It is vital to water just enough to prevent excess water of the floor of the greenhouse and watering early enough to allow plant surfaces to dry before entering the night. Additional care is needed to keep plants dry throughout the night when moisture can derive from condensation that drips from overhead structures onto the leaves or it forms on the leaves. Condensation on leaves occurs when the temperature of the leaf surface is below the dew point. Lower leaf temperatures are caused by temperature loss to cold clear skies at night. An energy curtain will reduce this energy loss or bottom heat can be provided. The dew point can also be lowered by air movement; to move humid air away from the leaves by ventilation that is enough to just slightly move the leaves. Bottom heat is useful also because it causes vertical air movement that pushes away high humidity. Moisture purging may also be necessary by forced ventilation. Finally, humidity can be reduced at the cost of additional heating. Effective environmental control reduces the pressure of disease and therefore reduced the use of plant chemicals. Ohio Florists' Association Bulletin 874. E-mail ofa@ofa.org www.ofa.org