When to Plant a Vegetable Garden in Seattle: Frost-Free Timeline by Crop Type

Planting

Planting a vegetable garden in Seattle means timing your crops to avoid the last frost on March 15 and the first one in mid-November — a window that rewards patience with a summer of homegrown bounty.

Seattle’s unpredictable weather can make or break your vegetable garden—planting at the wrong time means stunted growth or lost crops, while perfect timing unlocks a bountiful harvest. Here’s your frost-free planting schedule tailored to Seattle’s unique climate zones, from cool coastal areas to warmer inland regions.

Most gardeners in Zone 8a start cool-season crops like lettuce and peas indoors by February, while warm-season favorites such as tomatoes and peppers wait until after Memorial Day to avoid frost damage. The key? Knowing when to start seeds and when to transplant for maximum success.

Below, I break down the best planting windows by crop type, including succession planting tips and how to extend your harvest with row covers. Whether you’re a beginner or a seasoned gardener, this guide will help you grow a thriving 🌱 vegetable garden all season long.

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Seattle’s frost-free planting zones: when to start seeds indoors vs. outdoors

Seattle’s USDA Zones 7b-9a create a unique gardening puzzle—cool coastal breezes clash with warmer inland pockets, making timing everything. The average last frost date hovers around March 15, but microclimates can shift this by 2-3 weeks.

Inland areas like Redmond (Zone 9a) may see frost-free conditions by March 1, while West Seattle (Zone 7b) might linger until April 1. Understanding these zones helps you avoid frost damage to warm-season crops or bolting greens from early heat.

For indoor seed starting, I begin 4-8 weeks before transplanting, depending on the crop. Cold-hardy greens like kale and spinach can handle direct sowing in early March, while tomatoes and peppers need warm indoor conditions starting in February.

The key is matching your seedling maturity with Seattle’s frost-free window, which typically runs from late April to October.

Best vegetables to plant in Seattle by season: a month-by-month guide

Seattle’s cool, wet springs and mild summers create a unique growing window that rewards gardeners who plan carefully. Unlike warmer climates, we can’t plant everything in early spring—some crops need to wait until after Memorial Day to thrive.

The key is succession planting and knowing which veggies tolerate our unpredictable weather.

For example, leafy greens like kale and peas can handle early spring plantings, while tomatoes and peppers need to wait until soil temperatures stay above 55°F. Below, I’ve broken down the best planting times by month, including succession planting schedules to keep your harvests coming all season.

March: Start cool-season crops indoors—lettuce, spinach, and broccoli. Harden off seedlings by late April for outdoor planting.
April: Direct-sow radishes, carrots, and peas. Use row covers to protect early plantings from late frosts.
May: Plant potatoes, onions, and early cabbage. Wait until after May 20 for tomato and pepper seedlings to avoid frost.
June: Sow beans, cucumbers, and summer squash. Succession plant lettuce every 2 weeks for continuous harvests.
July: Extend season with fall crops like kale and Swiss chard. Start broccoli and cauliflower indoors for fall planting.
August: Plant garlic and cover crops like clover. Succession plant radishes and spinach for fall harvests.
September: Direct-sow cool-season crops for winter harvests. Use cold frames to extend growing season.

One of my favorite tricks for Seattle gardeners is succession planting. For example, lettuce can be sown every 2 weeks from April through August, ensuring a steady supply. Similarly, beans should be planted every 3 weeks for continuous pods. This method maximizes your garden space and reduces waste.

To extend your growing season, row covers and cold frames are game-changers. I’ve used lightweight row covers to protect broccoli and cabbage from late spring frosts, and cold frames to keep spinach and kale growing well into November.

These tools add 2-4 weeks to your harvest window, making the most of Seattle’s short growing season.

Don’t forget about fall planting! While many gardeners focus on spring, cool-season crops like carrots, beets, and Brussels sprouts thrive in Seattle’s mild autumn. Plant these in late August or early September for harvests in October and November.

With the right timing, you can enjoy fresh veggies well into the winter months.

For a foolproof approach, I recommend keeping a gardening journal to track planting dates, weather conditions, and harvest times. This helps you refine your schedule each year. For example, if tomatoes struggled in a cool June, you’ll know to wait until July next time. Happy gardening!

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Crop	Indoor Start Date	Outdoor Transplant Date	Direct Sow Date	Notes
Lettuce	March 1	March 15 (hardy)	March 1 - Sept 1	Succession plant every 2 weeks
Spinach	February 15	March 1 (cold-tolerant)	March 1 - April 30	Bolt-resistant varieties for summer
Kale	February 1	March 1 (hardy)	February 1 - Sept 15	Sweetens after frost
Tomatoes	February 15	May 15 (after last frost)	N/A (transplant only)	Use row covers for early starts
Peppers	March 1	May 20 (warm soil)	N/A (transplant only)	Need 80°F+ soil to thrive
Cucumbers	March 15	May 10 (warm soil)	N/A (transplant or direct)	Trellis for space-saving
Carrots	N/A (direct sow)	March 15 - Sept 1	March 1 - April 30, Sept 1	Loose soil prevents forking
Beans	N/A (direct sow)	May 15 (warm soil)	May 15 - July 1	Succession plant every 3 weeks
Broccoli	February 15	March 15 (hardy)	March 1 - April 30	Harvest before bolting
Basil	March 1	May 10 (after frost)	N/A (transplant only)	Heat-loving; avoid frost
Peas	N/A (direct sow)	March 1 - April 30	March 1 - April 30	Trellis for vertical growth