Allenspark 3NW, CO Frost Dates & Growing Season

The two dates every Allenspark 3NW garden is planned around, plus ready-computed planting windows for the most popular crops.

Last spring frost
Jun 14
~50% chance of frost after
First fall frost
Sep 12
~50% chance of frost before
Growing season
90 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 14 Jun 28
First fall frost Sep 25 Sep 12 Aug 25
Hard freeze (28°F), median last May 27 · first Sep 25

Computed from NOAA 1991–2020 climate normals at the ALLENSPARK 3NW 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 Allenspark 3NW

Computed from Allenspark 3NW'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 19 – May 3 Jun 21 – Jun 28
🫑 Peppers Apr 5 – Apr 19 Jun 28 – Jul 5
🥬 Lettuce May 3 – May 17 May 17 – May 31 May 17 – Jun 14
🫛 Peas May 3 – May 17
🥕 Carrots May 24 – Jun 14
🥦 Broccoli Apr 26 – May 10 May 24 – Jun 7
🥬 Kale May 3 – May 17 May 17 – May 31 May 17 – May 31
🥒 Cucumbers May 17 – May 24 Jun 21 – Jun 28 Jun 21 – Jun 28
🥒 Zucchini May 17 – May 24 Jun 21 – Jun 28 Jun 21 – Jun 28
🫘 Green Beans (Bush) Jun 21 – Jun 28
🌽 Sweet Corn Jun 21 – Jun 28
🌿 Basil May 3 – May 17 Jun 21 – Jun 28 Jun 28 – Jul 5
🧄 Garlic Fall: Aug 1 – Aug 29

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 Allenspark 3NW's dates automatically after a lookup.

Reading the season in Allenspark 3NW

At about 90 frost-free days, Allenspark 3NW 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 Allenspark 3NW, CO?

The average last spring frost in Allenspark 3NW is around Jun 14, 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 Allenspark 3NW, CO?

The average first fall frost in Allenspark 3NW arrives around Sep 12. 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 Allenspark 3NW?

About 90 frost-free days on average, from Jun 14 to Sep 12. 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 Allenspark 3NW 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.