When to plant cantaloupes in Colorado
Colorado’s average last spring frost is May 5, and the first fall frost typically arrives around October 1 — about 149 frost-free days (USDA zones 3b, 4b, 5a, 5b, 6a, 7a). Cantaloupe / Muskmelon needs 70–90 days to mature, which fits comfortably within Colorado's growing season.
Colorado covers a wide range of climates, so your exact frost dates may differ from the state average by two weeks or more. For dates tuned to your town, use the calendar generator.
When to plant cantaloupes in Colorado: the short answer
For a spring planting, plant out May 12 – May 29, with seeds started indoors Apr 7 – Apr 21. Wait until the soil is at least 70°F and frost is over.
Windows are ~1–2 week bands around each date. Frost dates are a statewide average from NOAA/NCEI normals; your town may differ by two weeks or more. Calendar year 2026.
How to grow cantaloupes in Colorado, step by step
- Start seeds indoors (Apr 7 – Apr 21). Sow seeds 1 inch deep in seed-starting mix under bright light. They take 4-10 days to sprout, fastest in soil around 85°F. Harden seedlings off for a week before they go outside.
- Prepare the bed. They need at least six to eight hours of direct sun a day and loose soil at least 18 inches deep, with a pH between 6.0 and 7.5. Dig in compost before planting.
- Plant out (May 12 – May 29). Space plants about 24 inches apart in rows 60 inches apart. It is killed by frost, so nothing goes outside until the danger has passed.
- Water and feed. Give it steady, even moisture, about an inch of water a week from rain or the hose.
- Watch for pests and problems. Pests: striped cucumber beetle, aphids, squash bug, squash vine borer. Diseases and disorders: powdery mildew, downy mildew, fusarium wilt, bacterial wilt.
- Harvest (from about Jul 28 – Aug 17). Cantaloupe / Muskmelon takes 70-90 days to reach harvest. Needs 70-90 warm days - start indoors in paper pots in short-season areas. Ripe when the fruit slips from the vine with a light tug and smells sweet at the blossom end. Ease off water as fruit ripens for sugar.
Figures come from our crop data; dates use Colorado’s average frost dates. More in the full cantaloupe / muskmelon growing guide.
Cantaloupe planting dates by USDA zone in Colorado
Colorado spans USDA zones 3b, 4b, 5a, 5b, 6a, 7a. Colder zones, usually higher or further inland, have a later last spring frost and an earlier first fall frost than the state average, so the cantaloupe / muskmelon dates shift with them.
| Zone | Last frost | First frost | Season | Start indoors | Plant cantaloupe / muskmelon |
|---|---|---|---|---|---|
| Zone 3 | May 15 | Sep 15 | 120 days | Apr 17 – May 1 | May 22 – Jun 8 |
| Zone 4 | May 10 | Sep 25 | 135 days | Apr 12 – Apr 26 | May 17 – Jun 3 |
| Zone 5 | Apr 30 | Oct 5 | 160 days | Apr 2 – Apr 16 | May 7 – May 24 |
| Zone 6 | Apr 15 | Oct 15 | 185 days | Mar 18 – Apr 1 | Apr 22 – May 9 |
| Zone 7 | Apr 5 | Oct 25 | 200 days | Mar 8 – Mar 22 | Apr 12 – Apr 29 |
When to plant cantaloupes in nearby states
Questions gardeners in Colorado ask
When is the best time to plant cantaloupes in Colorado?
Plant cantaloupe / muskmelon transplants outdoors in Colorado between May 12 and May 29. That timing is set by Colorado's average last spring frost of May 5; Colorado spans several climates, so cooler and higher parts of the state run later.
When should I start cantaloupe / muskmelon seeds indoors in Colorado?
Start seeds indoors between April 7 and April 21, about 3 weeks before the last frost, so the seedlings are ready to plant out from May 12.
What is the latest I can plant cantaloupes in Colorado?
About July 23. Cantaloupes need at least 70 days to mature, and frost around October 1 ends the season, so later plantings risk being cut short.
When will cantaloupes planted in Colorado be ready to harvest?
Planted on time, cantaloupes are usually ready from about July 28 to August 17, 70-90 days after planting.
When is the last frost in Colorado?
On average around May 5, with the first fall frost around October 1 - about 149 frost-free days. Your town may differ by two weeks or more.