Tiarella polyphylla D. Don is a native plant distributed only in Ulleung Island in Korea and has been traditionally used for medicinal purposes, although it is also used ornamentally. This study was conducted to determine the requirements for dormancy break and germination and to classify the type of seed dormancy. The experiments were performed with cold stratification (0 or 12 weeks at $5^{\circ}C$), warm stratification (0, 4, 8, or 12 weeks at $23^{\circ}C$, followed by 8 weeks at $5^{\circ}C$, and then incubation at $23^{\circ}C$), and $GA_3$ treatments (0, 10, 100, or 1000 mg/L). The treated seeds were incubated on aseptic media at room chamber ($23^{\circ}C$, a 16h photoperiod of fluorescent lamps with $40{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$). The seeds were dispersed in nature as underdeveloped embryos with no physical barrier to absorb water to prevent water absorption. However, the seeds did not germinate for 30 days after sowing without any pre-treatments. Thus, the seeds had morphological dormancy (MD) and physiological dormancy (PD). The final germination percentage following cold stratification (0 or 12 weeks) was 66.7% and 45.6%, respectively. The cold stratification delayed seed germination by about 3 weeks. In the warm stratification experiment (0, 4, 8, or 12 weeks), the final germination percentage was 21.1%, 27.8%, 41.1%, and 57.8%, respectively, 20 weeks after sowing. The embryos of the T. polyphylla seed grew in relatively warm temperatures ($23^{\circ}C$). $GA_3$ application overcame seed dormancy and promoted germination. Following $GA_3$ treatment (0, 10, 100, or 1000 mg/L), the final germination percentage was 33.3%, 45.0%, 42.5%, and 72.5%, respectively. These results suggest that the T. polyphylla seeds had non-deep simple morphophysiological dormancy (MPD) and $GA_3$ treatment could be used as a substitute for warm stratification for breaking seed dormancy. To our knowledge, this is the first report of seed dormancy characteristics of the genus Tiarella native to Korea.