The easy part of the answer is: Bouteloua dactyloides (Buffalograss) sets seed about 2 weeks after it blooms. The difficult part of the answer is: It can bloom beginning in April and bloom opportunistically when conditions are right until the first frost. Depending on the location that could be as late as November or December. In their book, Grasses of the Texas Hill Country, the Loflins say: "Bloom time starts in April and sets seed shortly after flowering up to the first frost. In some regions it produces seed throughout the year."