Warm-Season Vegetable

When to Plant Tomatoes in Washington

America's favorite garden vegetable (technically a fruit). Nothing beats a sun-warmed tomato straight off the vine.

The Short Answer

Washington State's dramatic east-west climate divide means tomato growing is two entirely different endeavors on either side of the Cascade Range. Western Washington — Seattle, Tacoma, Olympia — is a challenging tomato environment: cool summers, cloudy skies, and soil temperatures that stay stubbornly low well into June. Eastern Washington — the Yakima Valley, Tri-Cities, Spokane — is hot, sunny, and irrigated, producing conditions more like California's Central Valley. The key to western Washington tomatoes is accepting the limitations and choosing accordingly.

Washington Frost Dates

Your planting dates depend on which part of Washington you're in. Here are the frost date ranges by region:

Region Zones Last Frost (Spring) First Frost (Fall)
Western Washington (Seattle/Tacoma) 8a, 8b Mar 25 - Apr 15 Oct 25 - Nov 15
Puget Sound 8b, 9a Mar 15 - Apr 5 Nov 1 - Nov 20
Eastern Washington 5b, 6a, 6b, 7a Apr 25 - May 15 Sep 25 - Oct 15
Central Washington 6a, 6b, 7a Apr 20 - May 10 Oct 1 - Oct 20

Tomatoes Planting Schedule for Washington

Western Washington (Seattle/Tacoma) (Zones 8a, 8b)

Average last frost: Mar 25 - Apr 15 · Average first frost: Oct 25 - Nov 15

Start Seeds Indoors
6 wks before frost
Transplant Outside
2 wks after frost
Direct Sow
2 wks after frost

Puget Sound (Zones 8b, 9a)

Average last frost: Mar 15 - Apr 5 · Average first frost: Nov 1 - Nov 20

Start Seeds Indoors
6 wks before frost
Transplant Outside
2 wks after frost
Direct Sow
2 wks after frost

Eastern Washington (Zones 5b, 6a, 6b, 7a)

Average last frost: Apr 25 - May 15 · Average first frost: Sep 25 - Oct 15

Start Seeds Indoors
6 wks before frost
Transplant Outside
2 wks after frost
Direct Sow
2 wks after frost

Central Washington (Zones 6a, 6b, 7a)

Average last frost: Apr 20 - May 10 · Average first frost: Oct 1 - Oct 20

Start Seeds Indoors
6 wks before frost
Transplant Outside
2 wks after frost
Direct Sow
2 wks after frost

Growing Tomatoes in Washington

State-Specific Growing Tips

In western Washington (Zones 8a-8b), don't let the relatively mild frost dates fool you — the issue isn't frost danger, it's soil and air temperature. Wait until soil temperature reaches 60°F (often not until early June in the Puget Sound region) before transplanting. Use black plastic mulch to pre-warm soil for 2-3 weeks before transplanting. Plant against south-facing walls to capture reflected heat. In eastern Washington (Zones 6a-7a), transplant from mid-May and enjoy conditions that most tomato varieties love — hot days, cool nights, low humidity, and intense sun. The Columbia Basin's volcanic soils are excellent for vegetables with drip irrigation.

Recommended Varieties for Washington

Western Washington demands early, cool-tolerant varieties. Stupice (55 days, Czech origin, sets fruit in cool weather), Glacier (55 days), Early Girl (50 days), and Legend (developed at Oregon State for Pacific Northwest conditions) are the standards. Cherry tomatoes — Sungold, Sweet Million, and Sweetie — are far more reliable than large slicers in Puget Sound gardens. Eastern Washington gardeners have the luxury of growing any variety, including long-season heirlooms like Brandywine and Cherokee Purple. WSU Extension's variety trial data is exceptionally useful for both sides of the state.

Common Challenges in Washington

In western Washington, the primary challenge is insufficient heat — not pests or disease. Cool nights below 55°F slow fruit ripening and reduce overall yield. Late blight can appear during wet autumns, ending the season abruptly. In eastern Washington, spider mites and aphids thrive in the hot, dry conditions. Irrigation management is critical — the region receives less than 8 inches of rain annually. Wind protection helps in both the Columbia Gorge and the Palouse. Blossom end rot from inconsistent watering is common in eastern Washington's fast-draining soils.

Growing Tips

Pinch off suckers for indeterminate varieties. Stake or cage for best results. Water at the base, not overhead, to prevent blight.

Companion Planting

Plant tomatoes alongside these companions for better growth:

Basil Carrots Peppers Marigolds

Keep tomatoes away from:

Brassicas Fennel Dill

The Bottom Line

Tomatoes can be grown successfully in Washington with proper attention to regional frost dates and local growing conditions. Timing varies across the state — Western Washington (Seattle/Tacoma) gardeners work with a last frost around Mar 25 - Apr 15, while Central Washington sees frost end around Apr 20 - May 10. Choose varieties suited to your region, amend your soil based on its specific needs, and monitor for the pests and diseases most common in your area. For exact dates based on your zip code, use our free planting date finder.

Related Guides

Tomatoes Growing Guide National planting guide with all states Washington Planting Calendar All plants for Washington Tomatoes in Alabama Alabama planting dates Tomatoes in Alaska Alaska planting dates Tomatoes in Arizona Arizona planting dates Tomatoes in Arkansas Arkansas planting dates
Note: All dates are based on NOAA 30-year Climate Normals and represent historical averages, not predictions for any specific year. Always check your local weather forecast before planting frost-sensitive crops. Learn about our data sources.

Last reviewed: March 29, 2026

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