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Nonfl owering or sparse fl owering orchardgrass (Dactylis glomerata L.) would greatly simplify management of intensive rotational grazing systems. Our objective was to quantify seed production on nonfl owering orchardgrass clones selected in cold-winter climates, but grown for seed in mild-winter climates. We evaluated 98 orchardgrass clones for seed production traits at four locations. Most plants (~92%) fl owered at the three northern locations, but only 38% fl owered at Parlier, which may have a winter insuffi ciently cold for adequate fl oral induction and vernalization. Mean panicle number was lowest (11%) for plants selected at the location with the warmest winter conditions, and highest (37%) for plants selected at the location with the coldest winter conditions. These results confi rm our expectations that the most desirable plants (nonfl owering under cold winters and normal fl owering under mild winters) should arise from selection under more severe winters. Selection for nonfl owering under mild winter conditions simply leads to nonfl owering plants under all conditions. These results demonstrate that individual orchardgrass genotypes are capable of dual phenotypic expression, fl owering in mildwinter climates or expressing the nonfl owering trait in cold-winter climates and that the expression of this trait depends on both the selection and evaluation location.