The floral longevity of unpollinated, hand self‐, and hand cross‐pollinated flowers was compared in two varieties of Impatiens hypophylla, which contrasts with their mating systems. When flowers were emasculated and hand‐pollinated every day after anthesis, their longevity was reduced. In the absence of emasculation and hand pollination, the staminate phase of the flowers of both varieties was 1 d longer. After the staminate phase, flowers of the outcrossing variety dropped their androecium, exposing the stigma and initiating the pistillate phase, which lasted for ∼2 d. In contrast, flowers of the mixed‐mating variety self‐pollinated autonomously and then terminated their flowering. Under great seasonal variation in the pollinator visitation rate, which was observed in their natural populations, the outcrossing variety should maximize expected outcross success through the phenology of floral sex phases, whereas the mixed‐mating variety self‐pollinated ovules that were not outcrossed within the staminate phase. Based on these results, I suggest that the autonomous self‐pollination in I. hypophylla induced differences both in the selfing coefficient and in floral longevity between the varieties.