Frost Dates for Cortez, CO 81321

Last spring frost May 24 · First fall frost October 8 · 137 frost-free days · USDA Zone 7a

Frost probability for 81321

Frost10%50%90%
Spring (last frost)June 9May 24May 8
Fall (first frost)September 21October 8October 23

Dates come from NOAA 1971–2000 freeze probabilities at the nearest reporting station (22.6 km away); the 50% date is the median year.

Month by month in Cortez

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).
MarchStart peppers and eggplant indoors 8–10 weeks before your last frost (around May 24). Start tomatoes about two weeks later, 6–8 weeks before last frost.
AprilStart herbs, basil, and squash indoors (4–6 weeks before frost). Direct sow peas, spinach, and lettuce if soil is workable.
MayLast frost around May 24. Transplant cold-hardy crops (broccoli, kale, cabbage). Harden off tomato and pepper seedlings.
JuneFrost has passed. Transplant tomatoes, peppers, and basil outdoors. Direct sow beans, cucumbers, squash, and zucchini.
JulySuccession plant lettuce and greens. Keep beds weeded and watered consistently.
AugustHarvest regularly to encourage production. Monitor for pests and disease.
SeptemberFirst fall frost approaching (around October 8). Transplant fall brassicas. Sow spinach, arugula, and radishes.
OctoberFirst frost around October 8. Harvest tomatoes and peppers before frost. Cover cold-hardy crops with row covers to extend the season.
NovemberHarvest remaining cold-hardy crops: kale, carrots, and beets. Plant garlic bulbs for next year.
DecemberClean up spent plants. Add compost to beds. Rest, review, and plan next year's garden.

What grows in a 137-day season

Frequently Asked Questions

What is the last frost date for Cortez, CO (ZIP 81321)?

The median last spring frost date for Cortez, CO (ZIP code 81321) is around May 24. 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 Cortez, CO?

The median first fall frost date for Cortez, CO is around October 8. 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 Cortez, CO?

The frost-free growing season in Cortez is about 137 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 Cortez, CO?

Based on frost date patterns, Cortez falls approximately in 7a. 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 Cortez, CO?

Start tomato seeds indoors 6–8 weeks before your last frost date (around May 24). For Cortez, that's roughly March 29 to April 12. Transplant outdoors 1–2 weeks after your last frost.

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