Seed moisture content is the most reliable indicator of seed maturity and harvest timing in grass seed crops. There are two significant times during harvest that knowledge of seed moisture is critical: at swathing and at combining. Swathing within the correct range of seed moisture content will maximize seed yield and minimize seed losses during harvest. Taking an accurate measurement of seed moisture content is a key component of economic grass seed crop management. This publication covers these two topics relating to seed moisture: (1) The role of seed moisture in grass seed harvest systems. (2) How to accurately measure seed moisture on the farm.