• A slight breeze, such as a greenhouse fan, will also increase the evaporation rate. Position your orchid and Kool-Log so that the evaporation rate doesn’t exceed the transpiration rate of the log. You want the surface of the log to remain moist.

• And finally, humidity has a large affect on evaporative cooling. Using a Kool-Log in the Desert Southwest might give a 20 to 30 degree temperature drop on the surface of a Kool-Log. The rates of evaporation and cooling decrease as the humidity goes up. At 100% humidity no evaporation or cooling can take place. However, even in the typically hot and humid summers of the Southeastern U.S., my cool growing orchids have shown significant improvement in both growth and flowering on their Kool-Logs.​