| City | Aerate + overseed | Pre-emergent | Season |
|---|
| Billings | Aug 2 – Aug 17 | Apr 19 – May 10 | 144 days |
| Missoula | Aug 2 – Aug 17 | Apr 19 – May 10 | 144 days |
| Great Falls | Aug 2 – Aug 17 | Apr 15 – May 6 | 148 days |
All Montana station records (213)
Every NOAA weather station in Montana 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 Montana
Across the 216 Montana locations with complete 1991–2020 frost
normals, the average last spring frost — the anchor for pre-emergent and spring
work — ranges from Apr 30 (Norris Madison Pwr House) to Jun 18
(Tizer Gardens), a spread of about 7 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 Montana lawn year in one paragraph
Spring in Montana 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 Montana, when to aerate in Montana, when to apply crabgrass pre-emergent in Montana, and more above.