The humidity in the enviroment is the amount of water vapor present in the air. Most growers know that humidity in excess of 85% percent increases the probability of the appearance of bud mold. The humidity is also critical during germanation when the seedlings are extremely fragile. Humidty should be kept over 80% at this stage in the plants life to prevent the soil from drying too fast. Experimentation has shown that a relative humidity of 65% to 80% increases growth rate. Below this level the plants develop extremely narrow and tissue paper thin leaves to try to prevent excess loss of water. Above 80% relative humidity the plant have trouble disposing of toxic chemicals through evaporation.