USDA zone 7b in Washington
USDA plant hardiness zone 7b covers 13 locations across Washington (average annual extreme minimum 5 to 10 °F): Bickleton, WA, Centerville, WA, Chelan Falls, WA, Clarkston Heights-Vineland, WA, Desert Aire, WA, Elmer, WA, and 7 more. Average last spring frost across this group ranges March 24 (Desert Aire) to May 19 (Centerville), and growing seasons run 126–222 days (Centerville to Desert Aire) — even within one state, because hardiness sets winter survival, not planting dates. The table below gives every Washington location's own frost dates; the printable planting calendar uses Bickleton, this group's median-season location.
- USDA zone
- 7b5 to 10 °F
- Last frost range
- Mar 24–May 19avg, 32°F
- First frost range
- Sep 25–Nov 4avg, 32°F
- Growing season range
- 126–222days
Locations in this group
Every location below shares this zone and a nearby weather station, but keeps its own frost dates — find your town for its own numbers, or use the ZIP planner on the home page for an instant personalized answer.
| Location | Also covers | Nearest station | Last frost | First frost | Season (days) |
|---|---|---|---|---|---|
| Bickleton * | Arlington | Arlington | Apr 6 | Oct 21 | 196 |
| Centerville | Klickitat | Goldendale | May 19 | Sep 25 | 126 |
| Chelan Falls | — | Chelan | Apr 17 | Oct 22 | 187 |
| Clarkston Heights-Vineland | Asotin, Juliaetta | Lewiston Nez Perce Co Ap | Apr 6 | Oct 26 | 200 |
| Desert Aire | Beverly | Priest Rapids Dam | Mar 24 | Nov 4 | 222 |
| Elmer | — | Coulee Dam 1 Sw | Apr 22 | Oct 21 | 180 |
| Grandview | Prosser | Prosser | Apr 14 | Oct 22 | 189 |
| Kennewick | Finley | Kennewick | Mar 28 | Oct 30 | 216 |
| Outlook | — | Moxee City 10 E | May 4 | Oct 10 | 155 |
| Richland | West Richland, Benton | Richland | Apr 6 | Oct 24 | 200 |
| Starbuck | — | Dayton 1 Wsw | Apr 28 | Oct 13 | 168 |
| Wallula | — | Ice Harbor Dam | Apr 7 | Oct 22 | 199 |
| Wishram | Klickitat | The Dalles Muni Ap | Apr 11 | Oct 26 | 197 |
* Bickleton is this group's median-season location — the calendar below is computed from its data.
Data: NOAA NCEI U.S. Climate Normals 1991–2020 (public domain) and USDA Plant Hardiness Zone Map 2023. Planting windows synthesized from U.S. Cooperative Extension guides.
Planting calendar (Bickleton, representative)
Computed from Bickleton's average frost dates — the median-season location in this Washingtonzone 7b group. hatched = start seeds indoors, solid green = plant out, teal = a fall sowing, and the terracotta dot marks the estimated first harvest. Ranges are extension-guide planning guidance, not guarantees — your own location's dates may run a week or two earlier or later (see the table above).
- Start indoors
- Plant out
- Fall sowing
- First harvest
| Crop | Frost tolerance | Start indoors | Plant out | First harvest | Fall planting | Season fit |
|---|---|---|---|---|---|---|
| Tomato | Tender | Feb 9 – Feb 23 | Apr 13 – Apr 20 | Jun 12 – Jul 2 | — | matures comfortably |
| Pepper | Very tender | Jan 26 – Feb 9 | Apr 20 – Apr 27 | Jun 19 – Jul 19 | — | matures comfortably |
| Cucumber | Tender | Mar 9 – Mar 16 | Apr 13 – Apr 20 | Jun 2 – Jun 22 | — | matures comfortably |
| Summer squash / zucchini | Tender | — | Apr 13 – Apr 20 | May 28 – Jun 12 | — | matures comfortably |
| Bush bean | Tender | — | Apr 13 – Apr 20 | Jun 2 – Jun 12 | Aug 22 – Sep 1 | matures comfortably |
| Sweet corn | Tender | — | Apr 6 – Apr 20 | Jun 5 – Jul 5 | — | matures comfortably |
| Basil | Very tender | Feb 23 – Mar 9 | Apr 13 – Apr 20 | May 13 – May 28 | — | matures comfortably |
| Lettuce | Half-hardy | Feb 23 – Mar 9 | Mar 9 – Mar 23 | Apr 23 – May 8 | Aug 8 – Aug 23 | matures comfortably |
| Pea | Hardy | — | Feb 23 – Mar 9 | Apr 19 – May 4 | Jul 29 – Aug 13 | matures comfortably |
| Spinach | Hardy | — | Feb 23 – Mar 9 | Apr 4 – Apr 14 | Aug 18 – Aug 28 | matures comfortably |
| Carrot | Half-hardy | — | Mar 16 – Mar 23 | May 15 – Jun 4 | Jul 19 – Aug 8 | matures comfortably |
| Broccoli | Half-hardy | Feb 9 – Feb 23 | Mar 9 – Mar 23 | May 3 – May 23 | Jul 24 – Aug 13 | matures comfortably |
Which crops fit this growing season
Using Bickleton's own 196-day growing season (32°F, NOAA 1991–2020 median) against each crop's real days-to-maturity range: 12 of 12 crops mature here with comfortable margin. A different location in the table above with a longer or shorter season will get a different mix — the ZIP planner on the home page gives your own.
Frost & freeze dates (Bickleton)
From NOAA's 1991–2020 Climate Normals at station USC00350265. The median (p50) is the average date; the 90%-safe column is the date the freeze has passed in about 9 years out of 10 — the conservative date to plant after or harvest before.
| Threshold | Last spring — avg | Last spring — 90%-safe | First fall — avg | First fall — 90%-safe | Season (days) |
|---|---|---|---|---|---|
| 36°F | Apr 27 | May 10 | Oct 11 | Oct 25 | 168 |
| 32°F (freeze) | Apr 6 | Apr 28 | Oct 21 | Nov 7 | 196 |
| 28°F | Mar 19 | Apr 8 | Nov 3 | Nov 22 | 230 |
| 24°F | Mar 1 | Mar 20 | Nov 17 | Dec 12 | 262 |
Growing degree days
Growing degree days (GDD) accumulate warmth above a base temperature over the year — a better predictor of crop development than the calendar alone. This group's median GDD (base 50°F) across all 13 locations is 3,125; Bickleton's own reading is shown below.
| Model | °F·days | Used for |
|---|---|---|
| Base 50°F (warm-season) | 3,323 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 5,795 | cool-season crops (brassicas, greens) |
Hardiness zone 7b in Washington
Zone 7b means an average annual extreme minimum winter temperature of about 5 to 10 °F on the USDA's 2023 map — the number that tells you which perennials, shrubs, and trees reliably survive an average winter here. It does not set your planting dates, which come from the frost calendar above. Washington spans 8 hardiness zones in this dataset — see all Washington locations for the full range, including zones6a, 6b, 7a, 8a, 8b, 9a, 9b.
Explore zone 7b in other states at zone 7b, or see all USDA hardiness zones.
Frequently asked questions
- What does USDA hardiness zone 7b mean in Washington?
- Zone 7b means an average annual extreme minimum winter temperature of 5 to 10 °F — the standard USDA measure of which perennials survive winter. 13 locations in Washington fall in this zone. It does not set planting dates; see the frost calendar below for that.
- Where in Washington's zone 7b is the growing season longest?
- Desert Aire runs the longest season on this page at about 222 days; Centerville is shortest at about 126 days — they share the same hardiness zone, but they sit at different weather stations, so their frost calendars differ.
- When should I plant tomatoes in Washington's zone 7b?
- Using Bickleton's frost dates (this page's median-season location): start seeds indoors about Feb 9 – Feb 23, then transplant outside about Apr 13 – Apr 20. Your own location in the table above may differ by a week or two — use the ZIP planner on the home page for your exact station's dates.
- Does every location in Washington's zone 7b have the same frost dates?
- No — they do not all share a weather station, so frost dates vary by a week or more across the 13 locations listed (see the table above for each location's own dates).
Sources & method
Frost, freeze, growing-season, and growing-degree-day figures are NOAA NCEI U.S. Climate Normals 1991–2020, one reading per location's own nearest station (see the table above). The hardiness zone is the USDA Plant Hardiness Zone Map 2023, matched to each location's ZIP. Planting windows are computed by counting from the average last and first frost using per-crop offsets synthesized from U.S. Cooperative Extension guides — the full method and citations are on the methodology page.