Rustic 9WSW, CO Frost Dates & Growing Season

The two dates every Rustic 9WSW garden is planned around, plus ready-computed planting windows for the most popular crops.

Last spring frost
Jun 5
~50% chance of frost after
First fall frost
Sep 16
~50% chance of frost before
Growing season
103 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 24 Jun 5 Jun 20
First fall frost Sep 29 Sep 16 Sep 5
Hard freeze (28°F), median last May 22 · first Sep 26

Computed from NOAA 1991–2020 climate normals at the RUSTIC 9WSW 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 Rustic 9WSW

Computed from Rustic 9WSW'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 10 – Apr 24 Jun 12 – Jun 19
🫑 Peppers Mar 27 – Apr 10 Jun 19 – Jun 26
🥬 Lettuce Apr 24 – May 8 May 8 – May 22 May 8 – Jun 5
🫛 Peas Apr 24 – May 8
🥕 Carrots May 15 – Jun 5
🥦 Broccoli Apr 17 – May 1 May 15 – May 29
🥬 Kale Apr 24 – May 8 May 8 – May 22 May 8 – May 22
🥒 Cucumbers May 8 – May 15 Jun 12 – Jun 19 Jun 12 – Jun 19
🥒 Zucchini May 8 – May 15 Jun 12 – Jun 19 Jun 12 – Jun 19
🫘 Green Beans (Bush) Jun 12 – Jun 19
🌽 Sweet Corn Jun 12 – Jun 19
🌿 Basil Apr 24 – May 8 Jun 12 – Jun 19 Jun 19 – Jun 26
🧄 Garlic Fall: Aug 5 – Sep 2

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 Rustic 9WSW's dates automatically after a lookup.

Reading the season in Rustic 9WSW

At about 103 frost-free days, Rustic 9WSW 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 Rustic 9WSW, CO?

The average last spring frost in Rustic 9WSW is around Jun 5, 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 Rustic 9WSW, CO?

The average first fall frost in Rustic 9WSW arrives around Sep 16. 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 Rustic 9WSW?

About 103 frost-free days on average, from Jun 5 to Sep 16. 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 Rustic 9WSW 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.