When to plant in St. Helens, OR
USDA Zone 8bSt. Helens, Oregon frost dates, USDA zone, and a full-year planting calendar, drawn from the nearest NOAA station and tuned to the local season.
Zone 8b means many perennials and even some tender shrubs overwinter in St. Helens, while your frost dates still decide when annuals go out.
The average last spring frost in St. Helens is now 9 days earlier than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
SAINT HELENS RFD · 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 St. Helens’s own odds, recorded at SAINT HELENS RFD.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | Jun 9 | May 6 | Apr 18 | Oct 6 | Oct 24 | Nov 10 |
| 32°F | May 26 | Apr 18 | Mar 20 | Oct 21 | Nov 7 | Nov 26 |
| 28°F | May 6 | Mar 24 | Feb 20 | Nov 3 | Nov 24 | Dec 16 |
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 St. Helens, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 24 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.
St. Helens planting FAQ
When is the last spring frost in St. Helens, OR?
St. Helens's average last spring frost falls near April 18 — 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 St. Helens, OR?
The first fall frost in St. Helens typically arrives around November 7 (50% probability at 32°F). Harvest or protect frost-sensitive crops before then.
What hardiness zone is St. Helens in?
St. Helens is in USDA hardiness zone 8b. In zone 8b, winters are mild — many tender perennials overwinter here.
How long is the growing season in St. Helens?
There are roughly 203 frost-free days in St. Helens (a moderate growing season), running from the average last frost around April 18 to the first fall frost near November 7.
When should I plant tomatoes in St. Helens?
In St. Helens, start tomato seeds indoors around February 21–March 7, then transplant seedlings outdoors around April 25 once the danger of frost has passed.
Never miss a window in St. Helens
An email when it’s time to start seeds, transplant, and sow — timed to St. Helens’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Ridgefield · 12 km
- Felida · 18 km
- Mount Vista · 20 km
- Salmon Creek · 20 km
- Battle Ground · 23 km
- Hazel Dell · 23 km
- Five Corners · 27 km
- Minnehaha · 27 km
Frost dates recorded at SAINT HELENS RFD, 4 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 St. Helens, OR — Frost Dates & Zone 8b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00357466. Retrieved from https://blissgarden.com/oregon/st-helens.