May in the Pacific Northwest is a gardener’s sweet spot. Soil temperatures have climbed above 45°F in most of western Washington and Oregon, rainfall is still plentiful, and the long, mild days ahead favor exactly the crops that wilt the moment summer arrives elsewhere. If you’ve been waiting for the right moment to fill your beds, this is it — but the window for cool-season crops is narrower than it looks.
If you garden in the PNW and want a full-season planting framework, year-round vegetable gardening in the Pacific Northwest is worth bookmarking before you read on. It’s the broader context for everything below.
Why May Is Prime Time for Cool-Season Crops Here
The Cascade Range and Puget Sound moderate temperatures in ways that baffle gardeners from other regions. While zones 8a and 8b technically match parts of the Southeast, our summers are far cooler and our springs far wetter. That means:
- Frost risk drops to near zero in lowland western Oregon and Washington by early May, but it lingers in the foothills and eastern valleys.
- Soil moisture is still high enough that new transplants rarely need supplemental watering in the first few weeks.
- Daytime highs in the 55–65°F range are ideal for lettuce, brassicas, and peas — crops that turn bitter or bolt in July.
The practical upshot: plant cool-season crops now, harvest through June and into July, then transition beds to warm-season starts (tomatoes, beans, squash) in late May or June once the soil has warmed further.
The Best Cool-Season Crops to Direct-Sow in May
Peas
May is actually a second chance for peas if you missed the traditional St. Patrick’s Day planting. In the PNW, a mid-April through mid-May direct sow still gives you a productive crop before summer heat shuts them down. Sugar snap and snow pea varieties like ‘Oregon Sugar Pod’ and ‘Cascadia’ are bred for this climate.
Sow seeds 1 inch deep and 2 inches apart along a trellis or fence. They’ll germinate in 7–14 days in cool soil and don’t need fertilizer if your beds have reasonable organic matter.
Leafy Greens
Lettuce, spinach, arugula, and chard all thrive in May’s mild temperatures. The risk isn’t cold — it’s premature bolting if an early-summer warm spell arrives. Choose heat-tolerant lettuce varieties (‘Nevada’, ‘Jericho’, ‘Coastal Star’) and succession-plant every 2–3 weeks to extend harvest.
Direct sow spinach thickly and thin to 3 inches; thinnings are edible. For arugula, a light scatter-and-rake approach works fine. Expect harvest in 30–45 days for most greens.
Brassicas: Broccoli, Cabbage, Cauliflower, Kale
If you started seeds indoors in March or early April, May is transplant time for broccoli and cabbage. If you didn’t, you can still direct sow fast-maturing varieties — look for ‘De Cicco’ broccoli (48 days) or fast-heading cabbage in the 60–70 day range.
Kale can be direct sown now and harvested as baby greens in 3–4 weeks, or left to mature into full heads. ‘Lacinato’ (dinosaur kale) handles PNW rain and slug pressure better than curly types in most years.
A note on slugs: Brassica seedlings are slug magnets in our wet spring conditions. Copper tape around raised beds, iron phosphate bait (safe for pets and wildlife), and row cover for the first two weeks dramatically improve survival rates. For a thorough approach to the problem, see slug and snail management in Pacific Northwest vegetable gardens.
Radishes and Turnips
Radishes are the instant-gratification crop of May. French Breakfast and Cherry Belle varieties mature in 22–28 days. Direct sow in short rows every week or two and you’ll have a steady supply through June. Turnips take a bit longer (45–60 days) but store well and handle light frost if one does sneak through.
Cilantro and Dill
Both prefer cool weather and bolt in summer heat, making May their ideal planting window in the PNW. Direct sow both herbs where they’ll get morning sun and some afternoon shade. Succession-plant cilantro every 3 weeks; once it bolts, let it set seed (coriander) or pull and replant.
What to Hold Off On
This list isn’t about caution for caution’s sake — it’s about matching crops to the conditions we actually have in May, not the conditions we wish we had.
- Tomatoes and peppers: Transplant after your last frost date and, more importantly, after soil temperatures reach at least 60°F consistently. In western Washington, that’s typically late May through early June for lowland gardens. Rushing this loses weeks of growth to cold-stunted plants.
- Beans: Germination is poor below 60°F soil temperature. Wait until late May at the earliest; first week of June is safer for most PNW lowland areas.
- Squash and cucumbers: Same logic as beans. These crops stall in cold soil and are far more productive when planted into genuinely warm ground.
Bed Prep for a May Planting
If you haven’t already worked your soil since winter, a quick prep session makes a real difference. PNW soils are often waterlogged into April; by May they should be workable but may still have heavy structure from winter rain compaction.
- Loosen soil to 8–10 inches with a broadfork or garden fork. Avoid rototilling wet soil — it destroys structure.
- Work in 2–3 inches of finished compost. PNW soils tend toward acidity (pH 5.5–6.5), which suits most vegetables fine, but compost helps even out drainage and fertility.
- Rake smooth and let the bed settle for a day before planting if time allows.
Row Covers: A May Essential in the PNW
Even without frost risk, row covers (lightweight spunbond fabric, 0.5–0.9 oz) pull double duty in May: they protect transplants from slug feeding at night and buffer against the occasional cold snap in foothills gardens. They also accelerate germination by keeping soil a few degrees warmer.
Remove covers once plants are established (2–3 weeks) or when daytime temperatures consistently reach 70°F — whichever comes first. Leaving covers on too long in June traps heat and promotes disease in our already-humid conditions.
A Simple May Planting Schedule
The exact timing depends on your specific location — lowland Puget Sound, the Willamette Valley, and coastal Oregon all have slightly different rhythms. Use this as a starting framework.
| Week | Direct Sow | Transplant |
|---|---|---|
| Week 1 (May 1–7) | Radishes, lettuce mix, spinach, peas | Broccoli, cabbage |
| Week 2 (May 8–14) | Arugula, dill, cilantro, kale | Cauliflower, chard |
| Week 3 (May 15–21) | Second radish sowing, more lettuce | — |
| Week 4 (May 22–31) | Turnips, third lettuce succession | Early tomatoes (if soil is ready) |
Keep Growing Through the Season
For more on working with what the Pacific Northwest actually gives you — persistent rain, mild summers, and a long shoulder season — see growing vegetables in the Pacific Northwest rainy climate.
If you want a structured planting calendar that goes beyond a single season, the Harvest Home Gardening Books collection at GardeningByZone includes region-focused guides with month-by-month planting schedules for the Pacific Northwest and beyond. Worth having on the shelf before summer planning starts.