The best time to seed a cool-season lawn is in the late summer to early fall. Adequate soil moisture, warm soil, and limited weed pressure allow for excellent seedling growth. Normally, we recommend seeding between August 15 and September 15 as the optimum seeding window. However, due to our cool summer and a relatively cool forecast for August, we are recommending that you can start seeding anytime now and there is no need to wait until mid-August.
It is critical to seed as early as possible within this window. Even when seeding within this window, waiting one week later to seed may mean the turf will take 2 more weeks to mature as germination and subsequent growth slows later in the fall as temperatures cool. Additionally, annual bluegrass and other winter annual weeds will be more problematic with fall seeding dates than late summer seeding dates.
Seeding early (later summer) allows the turf to maximize its establishment and rooting prior to the next summer’s heat and drought.
For more information about establishment, see:
Aaron Patton, Turfgrass Extension Specialist