When to plant in Sammamish, WA
USDA Zone 8bEverything below — frost dates, hardiness zone, and what to plant when in Sammamish, Washington — is derived from the closest NOAA station with complete climate normals.
Sammamish's nearest full-normals station sits about 16 km out, so treat these as a close estimate — local microclimate can nudge your first and last frost. In zone 8b, Sammamish 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 Sammamish is now 6 days earlier than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
SNOQUALMIE FALLS · 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 Sammamish’s own odds, recorded at SNOQUALMIE FALLS.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 13 | Apr 26 | Apr 8 | Oct 4 | Oct 22 | Nov 7 |
| 32°F | Apr 21 | Mar 30 | Mar 4 | Oct 22 | Nov 7 | Dec 1 |
| 28°F | Mar 25 | Feb 27 | Jan 16 | Nov 6 | Nov 29 | Dec 31 |
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 Sammamish, 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.
Sammamish planting FAQ
When is the last spring frost in Sammamish, WA?
Plan for the last spring frost in Sammamish around March 30 (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 Sammamish, WA?
In Sammamish, the first 32°F freeze of fall lands around November 7 on average. Time your last harvests and any season-extension cover before it.
What hardiness zone is Sammamish in?
Sammamish is in USDA hardiness zone 8b. In zone 8b, winters are mild — many tender perennials overwinter here.
How long is the growing season in Sammamish?
Sammamish has about 222 frost-free days — a long growing season — between the average last spring frost (March 30) and first fall frost (November 7).
When should I plant tomatoes in Sammamish?
For Sammamish, sow tomatoes indoors about February 2–February 16 and move the seedlings out around April 6, after the last spring frost.
Never miss a window in Sammamish
An email when it’s time to start seeds, transplant, and sow — timed to Sammamish’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Issaquah · 6 km
- Bellevue · 9 km
- Union Hill-Novelty Hill · 10 km
- Redmond · 11 km
- Newcastle · 12 km
- East Renton Highlands · 14 km
- Snoqualmie · 14 km
- Mercer Island · 15 km
Frost dates recorded at SNOQUALMIE FALLS, 16 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 Sammamish, WA — Frost Dates & Zone 8b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00457773. Retrieved from https://blissgarden.com/washington/sammamish.