What Planting Zones Are in Washington?
Washington spans USDA hardiness zones 6a to 9b, where the average coldest winter night ranges from −10 °F to 30 °F (−23.3 °C to −1.1 °C). Zone 8b covers the most ZIP codes, 37%, and zones 6b to 9a together cover 87% of the state.
- Zone 6a2% · 17 ZIPs
- Zone 6b12% · 88 ZIPs
- Zone 7a18% · 125 ZIPs
- Zone 7b4% · 30 ZIPs
- Zone 8a7% · 47 ZIPs
- Zone 8b37% · 263 ZIPs
- Zone 9a19% · 137 ZIPs
- Zone 9b<1% · 1 ZIP
Bars show each zone's share of the 708 Washington ZIP codes in the official 2023 USDA ZIP code table; select a zone for its temperatures and hardy plants.
What Hardiness Zone Are Washington Cities In?
Seattle is in zone 9a, Spokane is in zone 7a, Tacoma is in zone 8b and Vancouver is in zone 8b. The table lists the zone, winter low and average frost dates for 20 Washington cities, using the ZIP code nearest each city center.
| City | ZIP | Zone | Winter low | Last frost | First frost |
|---|---|---|---|---|---|
| Seattle | 98121 | 9a | 20 °F to 25 °F | Mar 13 | Nov 17 |
| Spokane | 99201 | 7a | 0 °F to 5 °F | Apr 26 | Oct 12 |
| Tacoma | 98402 | 8b | 15 °F to 20 °F | Mar 8 | Nov 14 |
| Vancouver | 98661 | 8b | 15 °F to 20 °F | Mar 29 | Nov 9 |
| Bellevue | 98005 | 9a | 20 °F to 25 °F | Mar 8 | Nov 23 |
| Kent | 98031 | 8b | 15 °F to 20 °F | Mar 20 | Nov 10 |
| Everett | 98201 | 8b | 15 °F to 20 °F | Mar 24 | Nov 2 |
| Spokane Valley | 99216 | 7a | 0 °F to 5 °F | Apr 26 | Oct 15 |
| Renton | 98057 | 9a | 20 °F to 25 °F | Mar 13 | Nov 16 |
| Federal Way | 98023 | 8b | 15 °F to 20 °F | Mar 8 | Nov 14 |
| Yakima | 98902 | 7a | 0 °F to 5 °F | Apr 8 | Oct 23 |
| Bellingham | 98225 | 8b | 15 °F to 20 °F | Apr 1 | Nov 2 |
| Kennewick | 99336 | 7b | 5 °F to 10 °F | Mar 28 | Oct 30 |
| Lacey | 98503 | 8b | 15 °F to 20 °F | Apr 29 | Oct 14 |
| Bremerton | 98312 | 8b | 15 °F to 20 °F | Mar 29 | Nov 14 |
| Longview | 98632 | 8b | 15 °F to 20 °F | Apr 8 | Nov 5 |
| Wenatchee | 98801 | 7a | 0 °F to 5 °F | Apr 4 | Oct 28 |
| Mount Vernon | 98273 | 8b | 15 °F to 20 °F | Mar 24 | Nov 3 |
| Pullman | 99163 | 6b | −5 °F to 0 °F | May 6 | Sep 29 |
| Tumwater | 98501 | 8a | 10 °F to 15 °F | Apr 29 | Oct 14 |
Zone: 2023 USDA ZIP code table for the ZIP code nearest each city's Census center point. Frost dates: 50% (median) dates from the nearest NOAA station, 1991–2020 normals. Cities: the largest Washington places by 2024 Census population estimates, spread across the state, plus the largest place in each common zone. Large cities can span two half zones.
Which Parts of Washington Are in Each Zone?
Zone 6a, the coldest Washington zone, covers 2% of ZIP codes around Colville, Chewelah and Newport. Zone 9a, the warmest with towns, covers 19% around Seattle, Bellevue and Renton. The table lists the largest places in every zone.
| Zone | Avg. coldest night | Share of ZIPs | Largest places in this zone |
|---|---|---|---|
| Zone 6a | −10 °F to −5 °F | 2% (17) | Colville, Chewelah, Newport, Oroville |
| Zone 6b | −5 °F to 0 °F | 12% (88) | Pullman, Ellensburg, Liberty Lake, Cheney |
| Zone 7a | 0 °F to 5 °F | 18% (125) | Spokane, Spokane Valley, Yakima, Wenatchee |
| Zone 7b | 5 °F to 10 °F | 4% (30) | Kennewick, Pasco, Richland, West Richland |
| Zone 8a | 10 °F to 15 °F | 7% (47) | Tumwater, Lynden, North Bend, Chehalis |
| Zone 8b | 15 °F to 20 °F | 37% (263) | Tacoma, Vancouver, Kent, Everett |
| Zone 9a | 20 °F to 25 °F | 19% (137) | Seattle, Bellevue, Renton, Kirkland |
| Zone 9b | 25 °F to 30 °F | <1% (1) | Rural ZIP codes only |
Places: incorporated places with 1,000+ residents, assigned the zone of the ZIP code nearest their Census center point.
What Do the Hardiness Zones Mean for Washington Gardeners?
A Washington gardener in zone 9b sees winter lows about 35 °F milder than one in zone 6a, so a shrub or perennial that thrives in one part of the state can die in another. Choose plants rated to your own ZIP code's zone or colder.
Hardiness zones follow latitude, elevation and large bodies of water rather than state lines. Higher ground and inland valleys that trap cold air usually sit in colder half zones, while cities, coasts and large lakes moderate winter lows. Within Washington, a plant labelled “zones 6–9” survives winter in at least 87% of ZIP codes, but plants at the edge of their range benefit from mulch and a sheltered spot. Enter a ZIP code in the USDA hardiness zone finder by ZIP code to check your exact half zone before buying perennials.
A zone describes winter cold only. Summer heat, humidity, rainfall and soil decide whether a cold-hardy plant thrives, and planting dates for vegetables follow frost dates, not zones: two Washington towns in the same zone can have last frosts weeks apart.
What Plants Grow Well Across Washington?
134 plants in PlantoScan's catalogue are hardy in every zone from 6b to 9a, the zones that cover 87% of Washington ZIP codes. Popular examples include hydrangea, chrysanthemum and poppy.
Hydrangea
Hydrangea macrophylla
Zone 5 – 9
AI generated
Chrysanthemum
Chrysanthemum morifolium
Zone 5a – 9b
PlantoscanAI generated
Poppy
Papaver somniferum
Zone 3a – 9b
AI generated
Carnation
Dianthus caryophyllus
Zone 5a – 9b
AI generated
Azalea
Azalea indica
Zone 6a – 9b
AI generated
Arugula
Eruca sativa
Zone 5a – 10b
AI generated
Alfalfa
Medicago sativa
Zone 3a – 10a
AI generated
Japanese Maple
Acer palmatum
Zone 5a – 9b
AI generated
Wisteria
Wisteria sinensis
Zone 5a – 9b
AI generated
Hardiness ranges come from PlantoScan's plant database; gardeners in Washington's colder or warmer edge zones should check each plant's full range.
When Is the Last Frost in Washington?
Across most Washington ZIP codes, the average last spring frost falls between March 8 and May 13, from March 8 in Tacoma to May 6 in Pullman. Tender vegetables such as tomatoes go out 1 to 2 weeks after the local date.
The last and first frost dates for Washington cities include the safer 90% planting date, the fall frost date, growing season length and a tomato planting table for each city.
Frequently Asked Questions
- What planting zone is Washington?
- Washington spans USDA hardiness zones 6a to 9b on the 2023 USDA Plant Hardiness Zone Map. Zone 8b is the most common, covering 37% of the state's 708 ZIP codes, and zones 6b to 9a together cover 87%.
- What hardiness zone is Seattle, Washington?
- Seattle is in USDA hardiness zone 9a (ZIP 98121), where the average coldest winter night reaches 20 °F to 25 °F. Its average last spring frost is March 13 and its first fall frost November 17.
- What hardiness zone is Spokane, Washington?
- Spokane is in USDA hardiness zone 7a (ZIP 99201), where the average coldest winter night reaches 0 °F to 5 °F. Its average last spring frost is April 26 and its first fall frost October 12.
- What hardiness zone is Tacoma, Washington?
- Tacoma is in USDA hardiness zone 8b (ZIP 98402), where the average coldest winter night reaches 15 °F to 20 °F. Its average last spring frost is March 8 and its first fall frost November 14.
- What is the coldest hardiness zone in Washington?
- Zone 6a (−10 °F to −5 °F) is the coldest zone in Washington, found in 17 ZIP codes around Colville and Chewelah. The warmest is zone 9b (25 °F to 30 °F).
Zones: 2023 USDA Plant Hardiness Zone Map ZIP code table, USDA Agricultural Research Service and the PRISM Climate Group, Oregon State University, used without changes. Frost dates: NOAA National Centers for Environmental Information, 1991–2020 U.S. Climate Normals. City locations and populations: U.S. Census Bureau Gazetteer files and Vintage 2024 population estimates. PlantoScan is not affiliated with or endorsed by these agencies.