A method for reducing moisture of a material includes applying microwave radiation combined with RF to the material to heat and evacuate moisture from the material during a heating cycle and optionally alternating heating cycles with drying/cooling cycles. In particular, a method is disclosed to reduce a moisture content level of a material that comprises introducing the material or plant vertically into a drying enclosure using a vertical feed mechanism. The method further includes irradiating a portion of the material or plant with microwave to heat and vaporize moisture within the material or plant during a heating cycle; combining or alternating the microwave with RF heating for a time interval during the heating cycle to reduce the moisture content level of the material or plant; and alternating the heating cycle with a cooling cycle. In certain aspects or embodiments, the system comprises at least an enclosure, a vertical track mechanism, a microwave delivery device, a radio-frequency emitter and power supply.