Growth enhancement characteristics of plants are investigated using an atmospheric discharge plasma. Atmospheric pressure plasma torch is consisted of alumina ceramics tube and the steel mesh electrodes wound inside and outside of the tube. The growth enhancement was observed in the length of stem and root of plants after the plasma irradiation to seeds. The stem length increases approximately 2.8 times after the cultivation time of 24 h. And the effect is found to be maintained for 40 h, after sowing seeds. The mechanism of the growth enhancement would be the redox reaction inside plant cells induced by oxygen radicals.