a method of drying fresh plant material wherein the fresh plant material containing a desired heat labile compound is exposed to microwave energy at an intensity and for a time sufficient to remove a majority of the water from the plant material without degrading a majority of the heat labile compound . the method is particularly suited to in - field drying of freshly harvested plant material to reduce the weight and volume of the plant material for savings transportation costs to an extraction facility while preserving at high levels the amount and activity of the desired heat labile compound .