Frost Dates for Carbondale, CO 81623

Last spring frost July 6 · First fall frost August 21 · 46 frost-free days · USDA Zone 6a

Frost probability for 81623

Frost10%50%90%
Spring (last frost)July 23July 6June 19
Fall (first frost)August 1August 21September 10

Dates come from NOAA 1971–2000 freeze probabilities at the nearest reporting station (42.2 km away); the 50% date is the median year.

Month by month in Carbondale

MonthWhat to do
JanuaryPlan your garden layout and order seeds. Research varieties suited to your frost dates.
FebruaryStart the slowest-growing crops indoors: onions, leeks, and celery (10–12 weeks before last frost).
MarchOrganize planting supplies and seed-starting mix. Check stored garden tools.
AprilOrganize planting supplies and seed-starting mix. Check stored garden tools.
MayStart peppers and eggplant indoors 8–10 weeks before your last frost (around July 6). Start tomatoes about two weeks later, 6–8 weeks before last frost.
JuneStart herbs, basil, and squash indoors (4–6 weeks before frost). Direct sow peas, spinach, and lettuce if soil is workable.
JulyLast frost around July 6. Transplant cold-hardy crops (broccoli, kale, cabbage). Harden off tomato and pepper seedlings.
AugustFrost has passed. Transplant tomatoes, peppers, and basil outdoors. Direct sow beans, cucumbers, squash, and zucchini.
SeptemberHarvest remaining cold-hardy crops: kale, carrots, and beets. Plant garlic bulbs for next year.
OctoberClean up spent plants. Add compost to beds. Rest, review, and plan next year's garden.
NovemberClean up spent plants. Add compost to beds. Rest, review, and plan next year's garden.
DecemberClean up spent plants. Add compost to beds. Rest, review, and plan next year's garden.

What grows in a 46-day season

Frequently Asked Questions

What is the last frost date for Carbondale, CO (ZIP 81623)?

The median last spring frost date for Carbondale, CO (ZIP code 81623) is around July 6. This is the 50th-percentile date — meaning half of all years see frost end before this date. Use the 10% and 90% dates to understand the full range of risk in your area.

What is the first fall frost date in Carbondale, CO?

The median first fall frost date for Carbondale, CO is around August 21. Plan to harvest or protect frost-sensitive crops like tomatoes and peppers at least a week before this date to avoid losses.

How long is the growing season in Carbondale, CO?

The frost-free growing season in Carbondale is about 46 days. This window — from your last spring frost to your first fall frost — is when warm-season vegetables thrive. Cold-hardy crops like kale, spinach, and peas can extend your season by weeks on either side.

What USDA hardiness zone is Carbondale, CO?

Based on frost date patterns, Carbondale falls approximately in 6a. USDA hardiness zones are determined by average annual minimum winter temperatures and guide both plant selection and planting timing for your location.

When should I start tomatoes indoors in Carbondale, CO?

Start tomato seeds indoors 6–8 weeks before your last frost date (around July 6). For Carbondale, that's roughly May 11 to May 25. Transplant outdoors 1–2 weeks after your last frost.

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