Alamosa San Luis Airport, CO Frost Dates & Growing Season

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

Last spring frost
Jun 7
~50% chance of frost after
First fall frost
Sep 15
~50% chance of frost before
Growing season
100 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 7 Jun 24
First fall frost Sep 26 Sep 15 Sep 4
Hard freeze (28°F), median last May 23 · first Sep 25

Computed from NOAA 1991–2020 climate normals at the ALAMOSA SAN LUIS 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 Alamosa San Luis Airport

Computed from Alamosa San Luis Airport'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 12 – Apr 26 Jun 14 – Jun 21
🫑 Peppers Mar 29 – Apr 12 Jun 21 – Jun 28
🥬 Lettuce Apr 26 – May 10 May 10 – May 24 May 10 – Jun 7
🫛 Peas Apr 26 – May 10
🥕 Carrots May 17 – Jun 7
🥦 Broccoli Apr 19 – May 3 May 17 – May 31
🥬 Kale Apr 26 – May 10 May 10 – May 24 May 10 – May 24
🥒 Cucumbers May 10 – May 17 Jun 14 – Jun 21 Jun 14 – Jun 21
🥒 Zucchini May 10 – May 17 Jun 14 – Jun 21 Jun 14 – Jun 21
🫘 Green Beans (Bush) Jun 14 – Jun 21
🌽 Sweet Corn Jun 14 – Jun 21
🌿 Basil Apr 26 – May 10 Jun 14 – Jun 21 Jun 21 – Jun 28
🧄 Garlic Fall: Aug 4 – Sep 1

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 Alamosa San Luis Airport's dates automatically after a lookup.

Reading the season in Alamosa San Luis Airport

At about 100 frost-free days, Alamosa San Luis Airport 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 Alamosa San Luis Airport, CO?

The average last spring frost in Alamosa San Luis Airport is around Jun 7, 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 Alamosa San Luis Airport, CO?

The average first fall frost in Alamosa San Luis Airport arrives around Sep 15. 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 Alamosa San Luis Airport?

About 100 frost-free days on average, from Jun 7 to Sep 15. 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 Alamosa San Luis Airport 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.