Ross Dam, WA Frost Dates & Growing Season

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

Last spring frost
Apr 8
~50% chance of frost after
First fall frost
Nov 10
~50% chance of frost before
Growing season
216 days
frost-free stretch
USDA zone
≈ 9a
estimated from nearby reference
Risky (1 year in 10)MedianSafe (9 years in 10)
Last spring frost Mar 16 Apr 8 Apr 30
First fall frost Nov 25 Nov 10 Oct 26
Hard freeze (28°F), median last Mar 11 · first Nov 25

Computed from NOAA 1991–2020 climate normals at the ROSS DAM 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 Ross Dam

Computed from Ross Dam's own frost dates. Click any crop for the full zone-9 growing guide — varieties, spacing, fall plantings, and more.

CropStart seeds indoorsTransplantDirect sow
🍅 Tomatoes Feb 11 – Feb 25 Apr 15 – Apr 22
🫑 Peppers Jan 28 – Feb 11 Apr 22 – Apr 29
🥬 Lettuce Feb 25 – Mar 11 Mar 11 – Mar 25 Mar 11 – Apr 8
🫛 Peas Feb 25 – Mar 11
🥕 Carrots Mar 18 – Apr 8
🥦 Broccoli Feb 18 – Mar 4 Mar 18 – Apr 1
🥬 Kale Feb 25 – Mar 11 Mar 11 – Mar 25 Mar 11 – Mar 25
🥒 Cucumbers Mar 11 – Mar 18 Apr 15 – Apr 22 Apr 15 – Apr 22
🥒 Zucchini Mar 11 – Mar 18 Apr 15 – Apr 22 Apr 15 – Apr 22
🫘 Green Beans (Bush) Apr 15 – Apr 22
🌽 Sweet Corn Apr 15 – Apr 22
🌿 Basil Feb 25 – Mar 11 Apr 15 – Apr 22 Apr 22 – Apr 29
🧄 Garlic Fall: Sep 29 – Oct 27

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 Ross Dam's dates automatically after a lookup.

Reading the season in Ross Dam

With roughly 216 frost-free days, Ross Dam gardens fit long-season crops — melons, winter squash, sweet potatoes — with room left for spring and fall rounds of greens and roots. The first frost around Nov 10 is late enough that fall planting is a full second season, not an afterthought.

Frequently asked questions

When is the last frost in Ross Dam, WA?

The average last spring frost in Ross Dam is around Apr 8, 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 Ross Dam, WA?

The average first fall frost in Ross Dam arrives around Nov 10. 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 Ross Dam?

About 216 frost-free days on average, from Apr 8 to Nov 10. That comfortably fits long-season crops like melons and winter squash, plus spring and fall plantings of cool-season vegetables.

What USDA zone is Ross Dam in?

USDA zone 9a 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.