Dasysiphonia japonica is a red algae species that has recently invaded the northeastern coast of North America, spreading over 435 miles from Rhode Island to Maine in just 15 years. The invasion has resulted in a significant reduction in native algal and sessile species richness, and it now constitutes 14% of subtidal benthic communities. To investigate the factors promoting the rapid invasion of D. japonica, we conducted a study on its reproductive rate under summer and winter environmental conditions. We collected samples weekly from the field, weighed them, and allowed them to grow and reproduce asexually in growth chambers under summer (16-hour days at 14℃) and winter conditions (10-hour days at 4℃). After a week, we weighed the samples and counted the clonal fragments. The experiment was duplicated four times. ANOVA analysis confirmed that seasonal conditions significantly influence the number of clones produced per unit mass, with D. japonica producing significantly more clones per unit mass under summer conditions. These findings suggest that further research is necessary to explain how D. japonica has proliferated so quickly on the northeastern coast of North America. Additionally, our observations indicate that D. japonica has increased survivability in winter conditions, which may contribute to its success as an invasive species.