Washington Lawn Care Calendar

Washington is cool-season turf country — kentucky bluegrass, tall fescue, perennial ryegrass, fine fescue. Click a city for its full month-by-month calendar.

CityAerate + overseedPre-emergentSeason
Seattle Sep 18 – Oct 3 Feb 20 – Mar 13 249 days
Spokane Aug 13 – Aug 28 Apr 5 – Apr 26 169 days
Yakima Aug 5 – Aug 20 Apr 17 – May 8 149 days
🌾 Overseed in WA⛳ Aerate in WA🛡️ Apply Pre-Emergent in WA🧪 Fertilize in WA🧹 Dethatch in WA🍂 Stop Mowing in WA❄️ Winterize in WA

All Washington station records (151)

Every NOAA weather station in Washington with complete 1991–2020 frost normals — pick the one nearest you (similar elevation matters more than plain distance).

Not sure which station to trust? Use the ZIP code lookup for the quick answer, or pick the station whose terrain most resembles your yard.

Lawn timing geography of Washington

Across the 154 Washington locations with complete 1991–2020 frost normals, the average last spring frost — the anchor for pre-emergent and spring work — ranges from Feb 26 (Olga 2 SE) to Jun 6 (Davenport), a spread of about 14 weeks driven by elevation, latitude, and terrain. The same job can be weeks apart at opposite ends of the state, which is why a state-level date is only a starting point — pick the location nearest your yard and plan from its calendar.

The Washington lawn year in one paragraph

Spring in Washington is for prevention and restraint: crabgrass pre-emergent as soil approaches 55°F, one light feeding after green-up, and otherwise letting the lawn grow. Summer is defense — mow tall, water deeply or let it go dormant. Early fall is when lawns are actually built here: aerate, overseed, and give the main feeding while warm soil and cool air do the establishment work, then a winterizer feeding and a final mow around first frost close the year. Details by task: when to overseed in Washington, when to aerate in Washington, when to apply crabgrass pre-emergent in Washington, and more above.