In regard to the abilities of Zoysia japonica Steud. in elongating stolons and covering a ground surface, some investigations were made on the materials collected from various locations in Japan. The results indicate that there exist large variations in both abilities, which are also varied by environmental conditions. Total length of stolons were about twice in a year and 90 times in two years as compared with that at planting. However, there were great variations in stolon elongation among the populations collected from various parts of Japan. Those variations in total length were different each other between the following two practices: one was a whole-sod planting and the other was planting of pieces taken from stolons. In the year of planting, the stolons did not rapidly cover a ground surface. Each population showed its specific pattern of coverage of a ground surface in accordance with the distance from the center and with the growing seasons. The 10 populations studied were divided into three groups based on the degree of spreading of stolons and covering of a ground surface. The degree of covering was significantly affected by planting methods. On the basis of those patterns, the populations tasted were divided into four groups.