When to plant in Seattle, WA
USDA Zone 9aSeattle, Washington frost dates, USDA zone, and a full-year planting calendar, drawn from the nearest NOAA station and tuned to the local season.
A generous ~260-day season lets Seattle gardeners direct-sow more and still ripen long-maturity crops like melons and winter squash. Zone 9a is warm enough that Seattle can grow subtropical perennials, and the short (or absent) frost period barely limits the annual calendar.
Frost probability
SEATTLE SAND PT WSFO · 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 Seattle’s own odds, recorded at SEATTLE SAND PT WSFO.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | Apr 26 | Apr 4 | Mar 17 | Oct 24 | Nov 5 | Nov 22 |
| 32°F | Mar 29 | Mar 8 | Feb 13 | Nov 4 | Nov 23 | Dec 16 |
| 28°F | Mar 1 | Feb 11 | Dec 27 | Nov 17 | Dec 11 | Jan 17 |
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 Seattle, 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.
Seattle planting FAQ
When is the last spring frost in Seattle, WA?
Plan for the last spring frost in Seattle around March 8 (the date it has a 50% chance of a 32°F freeze). Anything frost-sensitive should go out after it.
When is the first fall frost in Seattle, WA?
Expect Seattle's first fall frost near November 23 — a 50% chance of 32°F by that date. Bring in or cover tender crops ahead of it.
What hardiness zone is Seattle in?
Seattle is in USDA hardiness zone 9a. In zone 9a, winters are mild — many tender perennials overwinter here.
How long is the growing season in Seattle?
There are roughly 260 frost-free days in Seattle (a long growing season), running from the average last frost around March 8 to the first fall frost near November 23.
When should I plant tomatoes in Seattle?
In Seattle, start tomato seeds indoors around January 11–January 25, then transplant seedlings outdoors around March 15 once the danger of frost has passed.
Never miss a window in Seattle
An email when it’s time to start seeds, transplant, and sow — timed to Seattle’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Mercer Island · 11 km
- Bainbridge Island · 12 km
- White Center · 12 km
- Kirkland · 14 km
- Bellevue · 15 km
- Shoreline · 15 km
- Burien · 16 km
- Bryn Mawr-Skyway · 16 km
Frost dates recorded at SEATTLE SAND PT WSFO, 10 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 Seattle, WA — Frost Dates & Zone 9a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USW00094290. Retrieved from https://blissgarden.com/washington/seattle.