Cascade 1 NW, ID Frost Dates & Growing Season

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

Last spring frost
May 30
~50% chance of frost after
First fall frost
Sep 19
~50% chance of frost before
Growing season
112 days
frost-free stretch
USDA zone
≈ 5b
estimated from nearby reference
Risky (1 year in 10)MedianSafe (9 years in 10)
Last spring frost May 10 May 30 Jun 21
First fall frost Oct 4 Sep 19 Sep 3
Hard freeze (28°F), median last May 6 · first Oct 2

Computed from NOAA 1991–2020 climate normals at the CASCADE 1 NW 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 Cascade 1 NW

Computed from Cascade 1 NW's own frost dates. Click any crop for the full zone-5 growing guide — varieties, spacing, fall plantings, and more.

CropStart seeds indoorsTransplantDirect sow
🍅 Tomatoes Apr 4 – Apr 18 Jun 6 – Jun 13
🫑 Peppers Mar 21 – Apr 4 Jun 13 – Jun 20
🥬 Lettuce Apr 18 – May 2 May 2 – May 16 May 2 – May 30
🫛 Peas Apr 18 – May 2
🥕 Carrots May 9 – May 30
🥦 Broccoli Apr 11 – Apr 25 May 9 – May 23
🥬 Kale Apr 18 – May 2 May 2 – May 16 May 2 – May 16
🥒 Cucumbers May 2 – May 9 Jun 6 – Jun 13 Jun 6 – Jun 13
🥒 Zucchini May 2 – May 9 Jun 6 – Jun 13 Jun 6 – Jun 13
🫘 Green Beans (Bush) Jun 6 – Jun 13
🌽 Sweet Corn Jun 6 – Jun 13
🌿 Basil Apr 18 – May 2 Jun 6 – Jun 13 Jun 13 – Jun 20
🧄 Garlic Fall: Aug 8 – Sep 5

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 Cascade 1 NW's dates automatically after a lookup.

Reading the season in Cascade 1 NW

At about 112 frost-free days, Cascade 1 NW 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 Cascade 1 NW, ID?

The average last spring frost in Cascade 1 NW is around May 30, 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 Cascade 1 NW, ID?

The average first fall frost in Cascade 1 NW arrives around Sep 19. 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 Cascade 1 NW?

About 112 frost-free days on average, from May 30 to Sep 19. 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 Cascade 1 NW in?

USDA zone 5b 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.