Silverton, OR Frost Dates & Growing Season

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

Last spring frost
Mar 28
~50% chance of frost after
First fall frost
Nov 10
~50% chance of frost before
Growing season
227 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 1 Mar 28 Apr 19
First fall frost Dec 1 Nov 10 Oct 25
Hard freeze (28°F), median last Feb 25 · first Nov 28

Computed from NOAA 1991–2020 climate normals at the SILVERTON 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 Silverton

Computed from Silverton'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 31 – Feb 14 Apr 4 – Apr 11
🫑 Peppers Jan 17 – Jan 31 Apr 11 – Apr 18
🥬 Lettuce Feb 14 – Feb 28 Feb 28 – Mar 14 Feb 28 – Mar 28
🫛 Peas Feb 14 – Feb 28
🥕 Carrots Mar 7 – Mar 28
🥦 Broccoli Feb 7 – Feb 21 Mar 7 – Mar 21
🥬 Kale Feb 14 – Feb 28 Feb 28 – Mar 14 Feb 28 – Mar 14
🥒 Cucumbers Feb 28 – Mar 7 Apr 4 – Apr 11 Apr 4 – Apr 11
🥒 Zucchini Feb 28 – Mar 7 Apr 4 – Apr 11 Apr 4 – Apr 11
🫘 Green Beans (Bush) Apr 4 – Apr 11
🌽 Sweet Corn Apr 4 – Apr 11
🌿 Basil Feb 14 – Feb 28 Apr 4 – Apr 11 Apr 11 – Apr 18
🧄 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 Silverton's dates automatically after a lookup.

Reading the season in Silverton

With roughly 227 frost-free days, Silverton 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 Silverton, OR?

The average last spring frost in Silverton is around Mar 28, 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 Silverton, OR?

The average first fall frost in Silverton 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 Silverton?

About 227 frost-free days on average, from Mar 28 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 Silverton 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.