The microwave setup for obtaining plasma-activated water (PAW) has been created. PAW contains significant concentrations of H2O2 and NO3−, has a reduced content of O2, high conductivity, a high redox potential and low pH. Likewise, the specific electrical conductivity and concentration of H2O2 and NO3− linearly depend on the treatment time. These parameters are simple and convenient markers for controlling the preparation of PAW. It has been established that PAW solutions with a concentration of 0.5–1.0% increase the germination energy, protect against fusarium and hyperthermia in cotton, wheat and strawberry seeds. In addition, PAWs have a positive effect on the growth rate of plants in the early stages of development. The use of PAW provides significant benefits over the chemical preparations Dalbron and Bakhor, so-called seed germination stimulators (SDS).