Substantial differences in germination rates of 10 Impatiens wallerana cultivars were demonstrated. Over the temperature range 15–30 °C, germination curves of the fast-germinating cultivars showed strong temperature dependence, whereas the slow-germinating cultivars showed only minor responses to temperature. The optimum germination temperature for all cultivars was 25 °C. Although continuous light (1200 lx) significantly enhanced germination, the degree of response was relatively small and cultivar-specific. Gibberellic acid (3 × 10−5 to 1.5 × 10−3 M) could substitute for the light requirement in these cultivars. A strong positive correlation between the rate of germination and the level of seedling establishment was demonstrated.