When to plant in Oregon City, OR
USDA Zone 9aHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for Oregon City, Oregon — all computed from Oregon City's nearest NOAA weather station.
With about 245 frost-free days, Oregon City supports back-to-back plantings; stagger sowings every few weeks to keep beds productive spring through fall. Zone 9a is warm enough that Oregon City can grow subtropical perennials, and the short (or absent) frost period barely limits the annual calendar.
Frost probability
OREGON CITY · 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 Oregon City’s own odds, recorded at OREGON CITY.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 4 | Apr 15 | Mar 26 | Oct 16 | Oct 31 | Nov 20 |
| 32°F | Apr 11 | Mar 18 | Feb 19 | Oct 30 | Nov 18 | Dec 12 |
| 28°F | Mar 7 | Feb 12 | Jan 1 | Nov 16 | Dec 8 | Jan 5 |
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 Oregon City, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 17 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.
Oregon City planting FAQ
When is the last spring frost in Oregon City, OR?
On average, the last spring frost in Oregon City is around March 18 (50% probability at 32°F, from 1991–2020 NOAA normals). Wait until after this date to set out tender plants like tomatoes and peppers.
When is the first fall frost in Oregon City, OR?
In Oregon City, the first 32°F freeze of fall lands around November 18 on average. Time your last harvests and any season-extension cover before it.
What hardiness zone is Oregon City in?
Oregon City is in USDA hardiness zone 9a. In zone 9a, winters are mild — many tender perennials overwinter here.
How long is the growing season in Oregon City?
There are roughly 245 frost-free days in Oregon City (a long growing season), running from the average last frost around March 18 to the first fall frost near November 18.
When should I plant tomatoes in Oregon City?
In Oregon City, start tomato seeds indoors around January 21–February 4, then transplant seedlings outdoors around March 25 once the danger of frost has passed.
Never miss a window in Oregon City
An email when it’s time to start seeds, transplant, and sow — timed to Oregon City’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- West Linn · 5 km
- Gladstone · 5 km
- Oatfield · 8 km
- Oak Grove · 9 km
- Canby · 11 km
- Lake Oswego · 12 km
- Milwaukie · 12 km
- Happy Valley · 12 km
Frost dates recorded at OREGON CITY, 2 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 Oregon City, OR — Frost Dates & Zone 9a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00356334. Retrieved from https://blissgarden.com/oregon/oregon-city.