Washington vegetable planting calendar 2027: frost dates and when to plant

In Washington, the average last spring frost is April 29 in Olympia and March 13 in Seattle (NOAA 1991-2020 normals). Below are planting dates for Olympia and Seattle for 27 common vegetables and herbs, worked out the way the Rowtime app does it: NOAA's average frost dates for the nearest weather station, with the planting rules of state extension guides. Dates are for the 2027 season.

Rowtime: Garden Planner works these dates out for your own ZIP code in Washington, shows where each one comes from, and recalculates when a planting slips. Get Rowtime on the App Store.

Dates are estimates. Check your local extension office before you plant, and use your own frost records if you have them. Dates shift by a week or more within a state, so pick the city closest to your conditions.

Olympia Seattle

Olympia

When to plant tomatoes in Olympia?

In Olympia, Washington, the average last spring frost is April 29 and the average first fall frost is October 14 (NOAA 1991-2020 normals, OLYMPIA AP station, 2.2 km from ZIP 98501). Planting dates here follow the planting table for western Washington from Washington State University Extension, not frost dates. For tomatoes, start seeds indoors April 8 to April 22 and plant out seedlings June 1 to June 15. Dates are for the 2027 season; sources last checked October 21, 2026.

Olympia Seattle

Seattle

When to plant tomatoes in Seattle?

In Seattle, Washington, the average last spring frost is March 13 and the average first fall frost is November 17 (NOAA 1991-2020 normals, SEATTLE BOEING FLD station, 8.2 km from ZIP 98104). Planting dates here follow the planting table for western Washington from Washington State University Extension, not frost dates. For tomatoes, start seeds indoors April 8 to April 22 and plant out seedlings June 1 to June 15. Dates are for the 2027 season; sources last checked October 21, 2026.

Olympia Seattle

Sources

Planting rules, in the order Rowtime tries them here:

• Oregon State University Extension Service, Vegetable Gardening in Oregon (Table 1. Planting dates, quantity to plant, and space for garden vegetables) (EC 871). Checked October 21, 2026.
• Washington State University Extension, Home Vegetable Gardening in Washington (Table 5. Suggested planting calendar for vegetable crops in the Pacific Northwest) (EM057E). Checked October 21, 2026.

Frost dates, locations and zones:

• NOAA National Centers for Environmental Information, U.S. Climate Normals 1991-2020 annual/seasonal (freeze probabilities).
• U.S. Census Bureau, 2025 Gazetteer Files: ZIP Code Tabulation Areas.
• PRISM Group, Oregon State University / USDA ARS, 2023 USDA Plant Hardiness Zone Map ZIP code listings. PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed 20 Oct 2026.

How the dates are worked out: a guide's rule such as "two weeks after the last frost" is applied to the station's NOAA date. Purdue's dates are 10% dates, so they are counted from the station's 10% date. When a guide gives no last date, the window closes early enough for the crop's longest days to harvest before the first fall frost. When a guide gives no first date for a fall planting, no fall window is shown. "Season too short" means the guide's window would close before it opens at this station's frost dates.

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