| City | Aerate + overseed | Pre-emergent | Season |
|---|
| Denver | Aug 13 – Aug 28 | Apr 9 – Apr 30 | 165 days |
| Colorado Springs | Aug 9 – Aug 24 | Apr 12 – May 3 | 158 days |
| Grand Junction | Aug 24 – Sep 8 | Mar 24 – Apr 14 | 192 days |
All Colorado station records (207)
Every NOAA weather station in Colorado 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 Colorado
Across the 210 Colorado locations with complete 1991–2020 frost
normals, the average last spring frost — the anchor for pre-emergent and spring
work — ranges from Apr 14 (Grand Junction) to Jun 21
(Boulder 14 W), a spread of about 10 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 Colorado lawn year in one paragraph
Spring in Colorado 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 Colorado, when to aerate in Colorado, when to apply crabgrass pre-emergent in Colorado, and more above.