| City | Aerate + overseed | Pre-emergent | Season |
|---|
| Portland | Oct 2 – Oct 17 | Feb 4 – Feb 25 | 279 days |
| Eugene | Aug 24 – Sep 8 | Mar 21 – Apr 11 | 195 days |
| Bend | Jul 22 – Aug 6 | May 16 – Jun 6 | 106 days |
| Medford | Aug 30 – Sep 14 | Mar 18 – Apr 8 | 204 days |
All Oregon station records (168)
Every NOAA weather station in Oregon 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 Oregon
Across the 172 Oregon locations with complete 1991–2020 frost
normals, the average last spring frost — the anchor for pre-emergent and spring
work — ranges from Jan 31 (Brookings) to Jun 11
(Burns Municipal Airport), a spread of about 19 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 Oregon lawn year in one paragraph
Spring in Oregon 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 Oregon, when to aerate in Oregon, when to apply crabgrass pre-emergent in Oregon, and more above.