Portland Troutdale Airport, OR Frost Dates & Growing Season

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

Last spring frost
Mar 16
~50% chance of frost after
First fall frost
Nov 20
~50% chance of frost before
Growing season
249 days
frost-free stretch
USDA zone
≈ 9a
estimated from nearby reference
Risky (1 year in 10)MedianSafe (9 years in 10)
Last spring frost Feb 18 Mar 16 Apr 12
First fall frost Dec 17 Nov 20 Oct 30
Hard freeze (28°F), median last Feb 14 · first Dec 15

Computed from NOAA 1991–2020 climate normals at the PORTLAND TROUTDALE AP 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 Portland Troutdale Airport

Computed from Portland Troutdale Airport'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 Jan 19 – Feb 2 Mar 23 – Mar 30
🫑 Peppers Jan 5 – Jan 19 Mar 30 – Apr 6
🥬 Lettuce Feb 2 – Feb 16 Feb 16 – Mar 2 Feb 16 – Mar 16
🫛 Peas Feb 2 – Feb 16
🥕 Carrots Feb 23 – Mar 16
🥦 Broccoli Jan 26 – Feb 9 Feb 23 – Mar 9
🥬 Kale Feb 2 – Feb 16 Feb 16 – Mar 2 Feb 16 – Mar 2
🥒 Cucumbers Feb 16 – Feb 23 Mar 23 – Mar 30 Mar 23 – Mar 30
🥒 Zucchini Feb 16 – Feb 23 Mar 23 – Mar 30 Mar 23 – Mar 30
🫘 Green Beans (Bush) Mar 23 – Mar 30
🌽 Sweet Corn Mar 23 – Mar 30
🌿 Basil Feb 2 – Feb 16 Mar 23 – Mar 30 Mar 30 – Apr 6
🧄 Garlic Fall: Oct 9 – Nov 6

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 Portland Troutdale Airport's dates automatically after a lookup.

Reading the season in Portland Troutdale Airport

With roughly 249 frost-free days, Portland Troutdale Airport 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 20 is late enough that fall planting is a full second season, not an afterthought.

Frequently asked questions

When is the last frost in Portland Troutdale Airport, OR?

The average last spring frost in Portland Troutdale Airport is around Mar 16, 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 Portland Troutdale Airport, OR?

The average first fall frost in Portland Troutdale Airport arrives around Nov 20. 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 Portland Troutdale Airport?

About 249 frost-free days on average, from Mar 16 to Nov 20. That comfortably fits long-season crops like melons and winter squash, plus spring and fall plantings of cool-season vegetables.

What USDA zone is Portland Troutdale Airport 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.