We investigated patterns of dormancy and reproduction over time in two long-lived grassland perennial species, Calochortus lyallii Baker and Calochortus macrocarpus Dougl. Three populations of each species were monitored over 5 years near Osoyoos, British Columbia, at the northern range limit for C. lyallii and near the elevational limit for C. macrocarpus. On average, C. macrocarpus bulbs flowered less frequently but had higher fruit set and produced more seeds per capsule than C. lyallii bulbs. In C. lyallii, low fruit set was related primarily to premature abortion of buds and flowers, whereas the potentially higher seed production of C. macrocarpus was largely offset by deer herbivory. Prolonged bulb dormancy was common in both species, with up to 18% of C. lyallii and 26% of C. macro carpus bulbs dormant in a given population and year. Dormancy episodes typically lasted a single year, although episodes as long as 4 years were also recorded. In both species dormancy was synchronized across sites, implying that it was not a random occurrence within populations but a response to the same external factor(s). Population surveys involving geophytes should consider the possibility that the visible population is not necessarily indicative of actual population size, and that a population may still be extant even when no individuals are observed.Key words: Calochortus, bulb dormancy, herbivory, range limits, geophyte, population persistence.