When to plant in Monmouth, OR
USDA Zone 8bEverything below — frost dates, hardiness zone, and what to plant when in Monmouth, Oregon — is derived from the closest NOAA station with complete climate normals.
In zone 8b, Monmouth supports a wide range of perennials year-round; the frost dates above are what set your annual vegetable timing.
The average last spring frost in Monmouth is now 5 days earlier than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
DALLAS 2 NE · 1991–2020The date the last spring and first fall frost occur, by threshold and probability. A 90% date is later in spring — and earlier in fall — than a 10% date; the 50% · 32°F row is what most gardeners plan around. These are Monmouth’s own odds, recorded at DALLAS 2 NE.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 23 | May 6 | Apr 19 | Sep 29 | Oct 13 | Nov 1 |
| 32°F | May 5 | Apr 16 | Mar 21 | Oct 13 | Nov 1 | Nov 22 |
| 28°F | Apr 8 | Mar 7 | Feb 2 | Oct 31 | Nov 20 | Dec 15 |
Download this table as CSV ↓ — every threshold and probability, plus this city’s planting-window dates.
What to plant now
TODAY · JULY 19Full-year planting calendar
Each bar is the exact window to take a planting action in Monmouth, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 19 km · complete 32°F normalsWhen stations disagree by more than a few days, that spread is real microclimate variation — elevation, water, urban heat. Judge which station best matches your own yard.
Monmouth planting FAQ
When is the last spring frost in Monmouth, OR?
Monmouth's average last spring frost falls near April 16 — the 50% mark at 32°F in the 1991–2020 normals. Hold tender transplants until the risk has passed, then plant out.
When is the first fall frost in Monmouth, OR?
In Monmouth, the first 32°F freeze of fall lands around November 1 on average. Time your last harvests and any season-extension cover before it.
What hardiness zone is Monmouth in?
Monmouth is in USDA hardiness zone 8b. In zone 8b, winters are mild — many tender perennials overwinter here.
How long is the growing season in Monmouth?
Monmouth has about 199 frost-free days — a moderate growing season — between the average last spring frost (April 16) and first fall frost (November 1).
When should I plant tomatoes in Monmouth?
For Monmouth, sow tomatoes indoors about February 19–March 5 and move the seedlings out around April 23, after the last spring frost.
Never miss a window in Monmouth
An email when it’s time to start seeds, transplant, and sow — timed to Monmouth’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Independence · 3 km
- Dallas · 10 km
- Salem · 18 km
- Four Corners · 22 km
- Keizer · 23 km
- Hayesville · 25 km
- Albany · 27 km
- Corvallis · 32 km
Frost dates recorded at DALLAS 2 NE, 12 km from the city center · 1991–2020 NOAA climate normals · zone from the USDA/PRISM 2023 map. How we compute this.
BlissGarden. "When to Plant in Monmouth, OR — Frost Dates & Zone 8b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00352112. Retrieved from https://blissgarden.com/oregon/monmouth.