Vallecito Dam, CO Frost Dates & Growing Season

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

Last spring frost
May 31
~50% chance of frost after
First fall frost
Sep 26
~50% chance of frost before
Growing season
118 days
frost-free stretch
USDA zone
≈ 6b
estimated from nearby reference
Risky (1 year in 10)MedianSafe (9 years in 10)
Last spring frost May 16 May 31 Jun 14
First fall frost Oct 8 Sep 26 Sep 14
Hard freeze (28°F), median last May 14 · first Oct 5

Computed from NOAA 1991–2020 climate normals at the VALLECITO DAM 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 Vallecito Dam

Computed from Vallecito Dam's own frost dates. Click any crop for the full zone-6 growing guide — varieties, spacing, fall plantings, and more.

CropStart seeds indoorsTransplantDirect sow
🍅 Tomatoes Apr 5 – Apr 19 Jun 7 – Jun 14
🫑 Peppers Mar 22 – Apr 5 Jun 14 – Jun 21
🥬 Lettuce Apr 19 – May 3 May 3 – May 17 May 3 – May 31
🫛 Peas Apr 19 – May 3
🥕 Carrots May 10 – May 31
🥦 Broccoli Apr 12 – Apr 26 May 10 – May 24
🥬 Kale Apr 19 – May 3 May 3 – May 17 May 3 – May 17
🥒 Cucumbers May 3 – May 10 Jun 7 – Jun 14 Jun 7 – Jun 14
🥒 Zucchini May 3 – May 10 Jun 7 – Jun 14 Jun 7 – Jun 14
🫘 Green Beans (Bush) Jun 7 – Jun 14
🌽 Sweet Corn Jun 7 – Jun 14
🌿 Basil Apr 19 – May 3 Jun 7 – Jun 14 Jun 14 – Jun 21
🧄 Garlic Fall: Aug 15 – Sep 12

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 Vallecito Dam's dates automatically after a lookup.

Reading the season in Vallecito Dam

At about 118 frost-free days, Vallecito Dam 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 Vallecito Dam, CO?

The average last spring frost in Vallecito Dam is around May 31, 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 Vallecito Dam, CO?

The average first fall frost in Vallecito Dam arrives around Sep 26. 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 Vallecito Dam?

About 118 frost-free days on average, from May 31 to Sep 26. 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 Vallecito Dam in?

USDA zone 6b 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.