When to plant in Mountlake Terrace, WA
USDA Zone 9aMountlake Terrace, Washington frost dates, USDA zone, and a full-year planting calendar, drawn from the nearest NOAA station and tuned to the local season.
With about 260 frost-free days, Mountlake Terrace supports back-to-back plantings; stagger sowings every few weeks to keep beds productive spring through fall. In zone 9a, frost is a minor factor for Mountlake Terrace — most perennials thrive, and annual vegetables can go out early and stay late.
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 Mountlake Terrace’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 Mountlake Terrace, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 22 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.
Mountlake Terrace planting FAQ
When is the last spring frost in Mountlake Terrace, WA?
On average, the last spring frost in Mountlake Terrace is around March 8 (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 Mountlake Terrace, WA?
The first fall frost in Mountlake Terrace typically arrives around November 23 (50% probability at 32°F). Harvest or protect frost-sensitive crops before then.
What hardiness zone is Mountlake Terrace in?
Mountlake Terrace is in USDA hardiness zone 9a. In zone 9a, winters are mild — many tender perennials overwinter here.
How long is the growing season in Mountlake Terrace?
Mountlake Terrace has about 260 frost-free days — a long growing season — between the average last spring frost (March 8) and first fall frost (November 23).
When should I plant tomatoes in Mountlake Terrace?
For Mountlake Terrace, sow tomatoes indoors about January 11–January 25 and move the seedlings out around March 15, after the last spring frost.
Never miss a window in Mountlake Terrace
An email when it’s time to start seeds, transplant, and sow — timed to Mountlake Terrace’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Alderwood Manor · 3 km
- Lynnwood · 4 km
- Lake Forest Park · 4 km
- Edmonds · 4 km
- Bothell West · 5 km
- Shoreline · 5 km
- Kenmore · 6 km
- North Lynnwood · 7 km
Frost dates recorded at SEATTLE SAND PT WSFO, 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 Mountlake Terrace, WA — Frost Dates & Zone 9a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USW00094290. Retrieved from https://blissgarden.com/washington/mountlake-terrace.