The paper presents the results of an experiment on the effect of cold plasma (He+Air) pre-sowing stimulation of seeds of onion type Wolska on the process of germination. Four groups of seeds characterized by the different exposure times (60, 120, 240 and 480 seconds) as well as untreated seeds - control were used. Pre-sowing plasma stimulation of seeds improved the germination parameters such as: germination capacity and germination energy for all tested groups relative to control. The highest germination parameters were obtained for seeds stimulated with plasma for the exposure times of 120 s. Analysis of the data showed a statistically significant impact of RF plasma on the seeds germination parameters of onion