AbstractTen varieties of forage grasses, including perennial and Italian ryegrasses, tall and meadow fescues, cocksfoot and timothy, grown in seed‐production drills were sequentially harvested from 14 days after peaks of flowering. Seed germination capacities were generally good in seed samples harvested early in the mattiration period, with the exception of timothy. PeaJc yields of germinable seed were usually obtained some time after shedding had begun; delay in harvesting resulted in further seed losses, some of which were substantial. The maxima of individual seed weights mostly did not coincide with, and were frequently later than the peaks of germinable seed yields. Endospenns did not generally harden until after the maxima of germinable seed yields. Endosperm development stages were found to be reliable guides to assessment of correct harvest date, and it is suggested that examination of endosperm consistencies be used to corroborate assessment of harvesting times tising moisture meter