Device and method suitable for disinfecting herbs using plasma are disclosed. The device comprises a chamber and two sets of electrodes in an opposed position one relative to the other, inside the chamber. Each electrode in one set has a counterpart electrode in the other set, the two electrodes positioned facing each other and being configured to connect to a RF HV power supply, to produce a plasma-generating EM field in the space between the electrodes. The device further comprises a dielectric carrier positioned inside the chamber in the space between the two sets of electrodes, the carrier being dimensioned and configured to carry herbs in granular form such as powder or particles thereon. A portable sealable container comprising a unidirectional valve is also disclosed, configured to store herbs thereinside during plasma treatment in the device, and to store the disinfected herbs after treatment under vacuum. A device for disinfecting herbs by evaporating a disinfection agent in an evacuated chamber is also disclosed where plasma is used in any of several methods to enhance, improve and expedite the disinfection process.