When to Plant a Vegetable Garden in Seattle: Frost Dates by Variety for Reliable Harvests

To plant a vegetable garden in Seattle, aim for late April to early May after the last frost—typically around April 15 for most of the city.

Seattle’s unpredictable weather can make or break your vegetable garden—plant too early, and frost ruins your crops; too late, and you miss peak harvest season. Timing is everything, but with the right frost date guide, you can maximize yields for tomatoes, lettuce, and more.

This guide breaks down the critical planting windows for Seattle’s USDA Zone 8a/8b, including cold-hardy greens like kale and peas that thrive early, versus heat-loving plants like peppers and basil that need warmer soil.

Learn how to adjust for microclimates, extend the season with row covers, and align your schedule with Seattle’s first fall frost—so you can enjoy a bountiful harvest from spring through fall.

Seattle’s frost dates by planting zone: critical timing for vegetable varieties

Seattle’s USDA Zone 8a/8b climate means last spring frost typically arrives between April 15–May 1, while first fall frost hits around October 15–November 1. These dates create a 180–200-day growing season, perfect for everything from cold-hardy peas to heat-loving tomatoes.

But timing isn’t one-size-fits-all—microclimates in urban areas like Ballard or West Seattle can delay frost by weeks compared to rural zones.

Understanding these frost dates helps you avoid common pitfalls like frost damage to seedlings or missed harvest windows. For example, basil and peppers need warm soil (60°F+) and won’t tolerate chilly nights, while kale and spinach thrive in cooler temps and can even survive light frosts.

Seattle’s rainy spring also means soil stays damp longer, delaying planting for heat-lovers until late May.

Here’s how to use frost dates to plan your garden: Start cold-hardy crops (peas, lettuce, spinach) as early as March 15 under row covers to protect from late frosts. Wait until May 15–June 1 for warm-season plants (tomatoes, peppers, basil), when soil temps consistently stay above 55°F.

Fall planting for broccoli and carrots should begin by July 15 to ensure harvest before frost.

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For heat-loving plants like tomatoes and peppers, soil temperature matters more than air temperature. Use a soil thermometer to confirm 60°F+ before planting—Seattle’s cool, damp springs often delay this until late May.

I’ve seen pepper seedlings stunted when planted too early, even if the air feels warm. To hedge your bets, start tomato and pepper seeds indoors in March and transplant after May 15.

Fall planting is equally critical. Broccoli and carrots sown by July 15 will mature before frost, while

Best vegetables to plant in Seattle’s spring vs. fall: month-by-month guide

Seattle’s spring and fall offer perfect windows for growing vegetables, but timing is key. Spring planting (March–May) focuses on cool-season crops, while fall planting (August–October) extends harvests into autumn. The secret? Succession planting—sowing seeds every 2–3 weeks to keep your garden productive.

For spring, start with hardy greens like lettuce and spinach in March, then transition to warm-weather crops like tomatoes and peppers by late April. In fall, prioritize cold-tolerant varieties such as kale and carrots, planting them by early September to harvest before the first frost.

Here’s your month-by-month breakdown for Seattle’s USDA Zone 8a/8b, including the best varieties and planting tips:

Pro tip: Extend your harvests by choosing fast-maturing varieties. For example, bush beans (50–60 days) and radishes (25–30 days) are perfect for succession planting in both seasons.

Seattle’s cool, wet climate rewards gardeners who plan ahead. By following this schedule, you’ll enjoy fresh vegetables from spring through fall—no gaps in your harvest! 🌱