Wyoming is cool-season turf country — kentucky bluegrass, tall fescue, perennial ryegrass, fine fescue. Click a city for its full month-by-month calendar.
| City | Aerate + overseed | Pre-emergent | Season |
|---|---|---|---|
| Cheyenne | Aug 2 – Aug 17 | Apr 23 – May 14 | 140 days |
| Casper | Jul 31 – Aug 15 | Apr 19 – May 10 | 142 days |
| Jackson | Jul 2 – Jul 17 | May 30 – Jun 20 | 72 days |
Every NOAA weather station in Wyoming with complete 1991–2020 frost normals — pick the one nearest you (similar elevation matters more than plain distance).
Across the 129 Wyoming locations with complete 1991–2020 frost normals, the average last spring frost — the anchor for pre-emergent and spring work — ranges from Apr 28 (Basin) to Jun 24 (Moose 1 NNE), a spread of about 8 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.
Spring in Wyoming 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 Wyoming, when to aerate in Wyoming, when to apply crabgrass pre-emergent in Wyoming, and more above.