Idaho Lawn Care Calendar

Idaho 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
Boise Aug 22 – Sep 6 Apr 3 – Apr 24 180 days
Idaho Falls Aug 2 – Aug 17 Apr 18 – May 9 145 days
Coeur d’Alene Aug 19 – Sep 3 Apr 1 – Apr 22 179 days
🌾 Overseed in ID⛳ Aerate in ID🛡️ Apply Pre-Emergent in ID🧪 Fertilize in ID🧹 Dethatch in ID🍂 Stop Mowing in ID❄️ Winterize in ID

All Idaho station records (124)

Every NOAA weather station in Idaho 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 Idaho

Across the 127 Idaho locations with complete 1991–2020 frost normals, the average last spring frost — the anchor for pre-emergent and spring work — ranges from Apr 2 (Brownlee Dam) to Jun 22 (Mccall), a spread of about 12 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 Idaho lawn year in one paragraph

Spring in Idaho 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 Idaho, when to aerate in Idaho, when to apply crabgrass pre-emergent in Idaho, and more above.