Planting
When to plant a vegetable garden in Seattle can make all the difference between a lush, productive harvest and a disappointing failure. With its mix of chilly coastal breezes and inland heatwaves, Seattle’s planting schedule isn’t one-size-fits-all—especially when comparing neighborhoods just miles apart.
Most gardeners here start cool-season crops like spinach and peas as early as March, but warm-season favorites like tomatoes and peppers need to wait until after the last frost—usually around May 15 in most of the city.
The key? Understanding whether you’re in the cooler, wetter coastal zone or the slightly warmer inland areas.
In this guide, I’ll break down exactly when to plant your vegetable garden based on Seattle’s microclimates, so you can maximize your harvest from spring to fall. Whether you’re a first-time gardener or a seasoned green thumb, these timing tips will help you avoid common pitfalls.
From extending your growing season with row covers to choosing the right crops for each month, you’ll learn how to make the most of Seattle’s unique climate—without guessing. Let’s get started!
Seattle’s planting zones: coastal vs. inland timing differences
Seattle’s microclimates create dramatic differences in planting schedules—just 10 miles inland can mean 2-3 weeks earlier for warm-season crops. The coastal areas (like West Seattle or Ballard) stay cooler and wetter longer, while inland zones (like Redmond or Kirkland) warm up faster.
Understanding these differences helps you avoid frost damage or bolting in heat-sensitive crops.
Most of Seattle falls in USDA Zone 8a, but the last average frost date varies: March 15 for coastal areas and March 1 for inland spots. Similarly, the first frost hits coastal areas around November 15, while inland zones can see frost as early as October 25.
These dates are your planting anchors—cool-season crops go in 4-6 weeks before last frost, and warm-season crops wait until 2 weeks after.
For example, lettuce and spinach thrive in coastal Seattle’s cooler springs but may bolt prematurely in inland heat. Meanwhile, tomatoes and peppers can start 2 weeks earlier inland than on the coast.
Even potatoes, which love cool soil, need to be planted 2 weeks later in coastal zones to avoid rot from excess moisture.
Here’s how the key planting windows compare across Seattle’s microclimates:
Use these microclimate rules to adjust your schedule: If you’re in Ballard or West Seattle, hold off on planting peppers until April 15. Inland gardeners in Kirkland can start cucumbers by March 25.
For potatoes, coastal gardeners should plant by March 1, while inland areas can wait until February 20.
Another trick? Watch your neighbors’ gardens—when cherry blossoms peak, it’s a sign to plant warm-season crops in inland areas. On the coast, wait until dandelions bloom fully. These natural indicators often align better with local microclimates than calendar dates.
Soil temperature also plays a critical role. Warm-season crops like tomatoes need soil at 60°F+, which coastal areas hit around mid-April, while inland zones reach this by late March.
Use a soil thermometer to confirm—planting too early in cold soil can stunt growth or invite damping-off disease.
Pro tip: Start seeds indoors 6-8 weeks before your last frost date to give seedlings a head start. For coastal gardeners, this means January 15 for broccoli or kale, while inland gardeners can begin February 1. This extended growing window
Best vegetables to plant by month in Seattle’s climate
Seattle’s cool, wet springs and mild summers create a unique growing window for vegetables. Unlike hotter climates, you can grow cool-season crops year-round with protection, while warm-season veggies thrive in summer’s brief warmth.
Let’s break down the best plants to sow each month, tailored for coastal (Zone 8a) and inland (Zone 8b) Seattle.
Start with hardy greens in February—spinach, kale, and peas love Seattle’s cool air. By March, expand to root vegetables like carrots and broccoli, which tolerate light frosts. Inland areas can plant early potatoes 2-3 weeks sooner than coastal zones due to faster warming soils.
| Month | Coastal Seattle | Inland Seattle | Key Tips |
|---|---|---|---|
| February | Peas, Spinach, Kale, Lettuce | Peas, Spinach, Onions, Radishes | Use row covers for frost protection |
| March | Broccoli, Carrots, Beets, Potatoes | Broccoli, Potatoes, Cabbage, Leeks | Test soil—amend with compost if clay-heavy |
| April | Green Beans, Cucumbers (late), Zucchini | Tomatoes, Peppers, Eggplant (after May 1) | Wait for soil temps >50°F for warm crops |
| May | Tomatoes, Peppers, Basil, Corn | Same + Early Succession Planting | Mulch to retain moisture and cool roots |
| September | Kale, Spinach, Radishes, Arugula | Same + Fast-Maturing Beets | Harvest warm-season crops before frost |
June through August is prime time for warm-season vegetables like tomatoes, peppers, and corn. Coastal areas should prioritize shade-tolerant varieties (e.g., ‘Stupice’ tomatoes) due to shorter daylight. Inland gardens can grow heat-loving crops like okra or sweet potatoes, but watch for pests like squash bugs that thrive in Seattle’s humidity.
Don’t overlook fall planting—September and October are perfect for cool-season crops. Try garlic in October for next year’s harvest or overwintering onions. Use cold frames to extend harvests into November for greens like Swiss chard.
Pro tip: Succession plant fast growers like radishes or lettuce every 2 weeks to avoid gluts. Seattle’s long growing season (165 frost-free days) lets you grow two full crops of most vegetables—plan accordingly!