Winthrop 1 WSW, WA Frost Dates & Growing Season

The two dates every Winthrop 1 WSW garden is planned around, plus ready-computed planting windows for the most popular crops.

Last spring frost
May 15
~50% chance of frost after
First fall frost
Sep 22
~50% chance of frost before
Growing season
130 days
frost-free stretch
USDA zone
≈ 6b
estimated from nearby reference
Risky (1 year in 10)MedianSafe (9 years in 10)
Last spring frost Apr 30 May 15 Jun 1
First fall frost Oct 2 Sep 22 Sep 10
Hard freeze (28°F), median last May 1 · first Oct 3

Computed from NOAA 1991–2020 climate normals at the WINTHROP 1 WSW station. "Safe" means frost past that date happens only about one year in ten. Your exact garden can still run days either way with elevation and terrain — check your own ZIP with the frost date lookup.

Planting windows for Winthrop 1 WSW

Computed from Winthrop 1 WSW's own frost dates. Click any crop for the full zone-6 growing guide — varieties, spacing, fall plantings, and more.

CropStart seeds indoorsTransplantDirect sow
🍅 Tomatoes Mar 20 – Apr 3 May 22 – May 29
🫑 Peppers Mar 6 – Mar 20 May 29 – Jun 5
🥬 Lettuce Apr 3 – Apr 17 Apr 17 – May 1 Apr 17 – May 15
🫛 Peas Apr 3 – Apr 17
🥕 Carrots Apr 24 – May 15
🥦 Broccoli Mar 27 – Apr 10 Apr 24 – May 8
🥬 Kale Apr 3 – Apr 17 Apr 17 – May 1 Apr 17 – May 1
🥒 Cucumbers Apr 17 – Apr 24 May 22 – May 29 May 22 – May 29
🥒 Zucchini Apr 17 – Apr 24 May 22 – May 29 May 22 – May 29
🫘 Green Beans (Bush) May 22 – May 29
🌽 Sweet Corn May 22 – May 29
🌿 Basil Apr 3 – Apr 17 May 22 – May 29 May 29 – Jun 5
🧄 Garlic Fall: Aug 11 – Sep 8

Want this for all 50 crops, or as a printable seed-shelf schedule? Use the planting calendar and the seed starting scheduler — both can use Winthrop 1 WSW's dates automatically after a lookup.

Reading the season in Winthrop 1 WSW

At about 130 frost-free days, Winthrop 1 WSW rewards efficiency: start warm-season crops indoors, favor short-season varieties, and lean on cold-tolerant crops — peas, kale, roots — that shrug off the shoulder-season frosts on either end.

Frequently asked questions

When is the last frost in Winthrop 1 WSW, WA?

The average last spring frost in Winthrop 1 WSW is around May 15, based on 1991–2020 climate normals. That's a median — about half of years see a later frost, so tender crops are safest going out a week or two after this date.

When is the first frost in Winthrop 1 WSW, WA?

The average first fall frost in Winthrop 1 WSW arrives around Sep 22. Crops still in the garden need to mature before then, and frost-tender plants need harvesting or protection as the date approaches.

How long is the growing season in Winthrop 1 WSW?

About 130 frost-free days on average, from May 15 to Sep 22. That favors short-season varieties and transplants for warm-season crops, with cool-season vegetables doing the heavy lifting in spring and fall.

What USDA zone is Winthrop 1 WSW in?

USDA zone 6b on the 2023 Plant Hardiness Zone Map. Note that zones describe winter cold, not frost timing — these frost dates are the numbers to plan plantings around.