The road slopes have various problems such as the risk of landslides and soil erosion, and research on stabilizing road slopes using plant greening has attracted the most attention. The overall objective of this research was to evaluate the effects of woody biomass based growing media on plant germination in a slope area. Moreover, we tried to find out what physicochemical properties of growing media affect plant germination on a slope. For experiment, we tested soil, soil mixed with growing media (1:1, w/w), and growing media by itself. Physical and chemical properties were evaluated after a month from the date of treatment application to the experimental slope site. Plant germination of Lespedeza cyrtobotrya was measured for plant growth evaluation. Physicochemical properties were altered by mixing the soil with growing media. Particularly, moisture content, organic matter and C/N ratio were significantly changed in soils mixed with growing media compared to soil alone. We confirmed that plant germination was high when growing media was mixed with the soil. There was a significant linear relationship between particle density and pH of all media tested and plant germination. In addition, in the same trend, the principal component analysis confirmed that the particle density and pH was positive component for plant germination rate, and the C/N ratio was found to be the negative component for plant germination. In conclusion, the particle density, pH and C/N ratio of the soil mixed with growing media was considered effective for plant germination in the experimental slope site, and this wood-based growing media provides a means to improve the harmony between the slope and the surrounding environment.