When to Plant Lettuce in Seattle, WA
Published: April 21, 2026
Lettuce Planting Dates for Seattle, WA
| Start seeds indoors | April 9–16 |
| Last frost (average) | May 7 |
| Transplant outdoors | April 9–19 |
| Direct sow outdoors | March 26–April 5 |
| Minimum soil temperature | 40°F |
| Expect first harvest | May 9 – June 8 |
| Fall crop planting | August 20–30 |
| Fall crop harvest | September 19 |
| First fall frost (average) | October 1 |
Best Lettuce Varieties for Seattle, WA
For Zone 4b Seattle, the best-performing lettuce varieties are Arctic King, Winter Marvel, and Tom Thumb — all short-season varieties chosen for cool-climate reliability. These varieties are typically stocked by local nurseries and are the safest bets for gardeners new to lettuce in Seattle.
Growing Lettuce in Seattle
Seattle sits in Zone 4b, with an average last frost of May 7 and first fall frost around October 1 — giving a 147-day frost-free growing season. Cool-season crops like lettuce benefit from Seattle's cooler spring and fall windows, when temperatures stay in the 55–75°F sweet spot that produces the best flavor and least bolting.
Seattle's cooler summers are close to ideal for lettuce. The same conditions that limit tomato and pepper yields benefit cool-season crops — slower bolting, sweeter flavor, and longer harvest windows. The fall lettuce crop in Seattle is often more productive than the spring crop.
Seattle's well-draining loam soils are among the best for lettuce growing — focus on annual organic matter additions (2 to 3 inches of compost) and consistent moisture during drier months. Water lettuce at 1 inches per week; loam holds moisture evenly without the drought-crack cycle of heavy clay or the rapid-drain losses of pure sand.
Lettuce Calendar for Seattle
| Month | Task |
|---|---|
| April | Start seeds indoors under grow lights |
| May | Last frost — harden off seedlings outdoors |
| April | Transplant outdoors into warm soil |
| May | Expect first harvest window to open |
| August | Start fall crop — transplants or direct sow |
| October | First fall frost — harvest remaining, end of outdoor season |
Lettuce Tips for Seattle Gardeners
- •Direct sow very shallowly — lettuce seeds need light to germinate; cover with just 1/8 inch of soil.
- •Cut outer leaves 1 inch above the crown for "cut-and-come-again" harvests lasting weeks.
- •Fall plantings in Seattle often out-produce spring plantings — cooler temperatures slow bolting and concentrate flavor. Light frost can actually improve the taste of lettuce.
Common Lettuce Pests in Seattle
- •Aphids — peaks July in Zone 4b (active June–August); clusters on leaf undersides; blast with a strong water spray or apply neem oil.
- •Slugs — peaks July in Zone 4b (active June–August); active at night; set beer traps or use iron phosphate pellets.
- •Cutworm — peaks July in Zone 4b (active June–August); cuts seedlings at soil line; protect stems with paper collars or diatomaceous earth.
Check plants every 2–3 days during peak season — early intervention prevents most infestations from becoming serious.
What to Plant with Lettuce in Seattle
In Seattle's cold climate, Carrot and Radish are the most beneficial plants to grow alongside lettuce. Carrot shares root-zone space without competing because carrot roots run deeper than most companions. Keep lettuce away from Fennel — it releases root chemicals that inhibit growth of most neighbors. In short-season gardens, interplanting companions at transplant time maximizes each bed's productive weeks.
Frequently Asked Questions
When should I plant lettuce in Seattle, WA?
In Seattle (Zone 4b), start lettuce seeds indoors around April 9–16 and transplant outdoors around April 9–19. The city's average last frost of May 7 is the anchor date — count 4 weeks back for seed starting and 4 weeks back for transplanting.
What zone is Seattle, WA for lettuce growing?
Seattle is USDA Zone 4b. For lettuce, this means a frost-free growing season of roughly 21 weeks running from May 7 to October 1. Cool-season crops like lettuce thrive in this zone with both spring and fall planting windows available.
When is lettuce harvest season in Seattle?
Expect the first lettuce harvest in Seattle around May 9, with harvest continuing through June 8. This is based on 30–60 days from transplant or direct sow. A fall crop planted August 20–30 adds a second harvest around September 19.
How long does it take to grow lettuce in Seattle, WA?
From transplant or direct sow to first harvest, lettuce takes 30–60 days in Seattle's climate. Based on a typical planting date of April 9–19, expect your first harvest around May 9. Seattle's cooler Zone 4b climate often lands at the slower end of this range — cooler nights slow fruit development.
What soil does lettuce need in Seattle?
Seattle's loam soil is near-ideal for lettuce. Work in 2–3 inches of compost before planting to boost organic matter and nutrient content. Minimal amendment is needed beyond that — loam holds moisture evenly without the drought-crack cycle of clay or the nutrient-loss issues of sandy soil.