This paper reports the stimulation of wheat seedling growth by using plasma-treated water. A nanosecond pulsed generator in a gas bubble-in-liquid system with a point-to-plate electrode was employed to treat de-ionised (DI) water, producing mainly hydrogen peroxide (H2O2) in the water when argon gas was used, and nitrate (NO3-) when air was used. The H2O2 and NO3- generated, respectively, in argon and air plasma-treated water significantly increased the growth parameters such as biomass, leaf length, and the relative chlorophyll content of the wheat seedling. The total biomass of the seedlings grown in potting mix after 4 weeks was augmented by 61 and 87%, respectively, for argon plasma-treated water and air plasma-treated water compared with the control (untreated DI water). In hydroponics, the biomass of the seedling increased 27 and 38%, respectively, for the argon and the air after 2 weeks in comparison to the control. In potting mix, the shoots and roots of the seedlings responded differently to the treated water: the biomass of shoot increased 33% for air plasma-treated water compared with the argon, while that of root increased 17% for argon plasma-treated water compared with the air. A separate experiment in hydroponics with chemical solutions of H2O2 and NO3- matching with the concentrations of the H2O2 and NO3- generated in the plasma-treated water showed similar stimulation of wheat seedling growth.