When to plant pumpkins 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). Pumpkin needs 90–120 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 pumpkins in Colorado: the short answer
For a spring planting, plant out May 5 – May 22, with seeds started indoors Apr 7 – Apr 21. Wait until the soil is at least 60°F and frost is over. For Halloween, count back 90–120 days from October 1: sow by Jun 3–Jul 3. See the Halloween plan.
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 pumpkins 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 5-10 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 5.5 and 7.5. Dig in compost before planting.
- Plant out (May 5 – May 22). Space plants about 48 inches apart in rows 96 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: squash vine borer, squash bug, striped cucumber beetle. Diseases and disorders: powdery mildew, bacterial wilt.
- Harvest (from about Aug 10 – Sep 9). Pumpkin takes 90-120 days to reach harvest. For Halloween pumpkins in the north, count back 100-120 days from 31 Oct and start indoors. Mini varieties can climb a strong trellis.
Figures come from our crop data; dates use Colorado’s average frost dates. More in the full pumpkin growing guide.
Planting pumpkins in Colorado for Halloween
Spring dates above suit a long season. If you want fruit ready for Halloween, count back from Colorado's average first fall frost (October 1), which comes before Halloween. Pumpkin takes 90–120 days from sowing to a mature fruit, so these are the latest sowing dates. Sow earlier for a margin, but not too early: the University of Arkansas Extension warns that pumpkins planted too early may rot before Halloween.
| Days to maturity | Latest sowing for Halloween | Typical for |
|---|---|---|
| 120 days | June 3 | slowest types (giants) |
| 100 days | June 23 | jack-o'-lantern and pie types (University of Arkansas variety table) |
| 90 days | July 3 | quickest types |
See the full growing guide for pumpkin. Days to maturity vary by variety, so check the seed packet.
Pumpkin 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 pumpkin dates shift with them.
| Zone | Last frost | First frost | Season | Start indoors | Plant pumpkin |
|---|---|---|---|---|---|
| Zone 3 | May 15 | Sep 15 | 120 days | Apr 17 – May 1 | May 15 – Jun 1 |
| Zone 4 | May 10 | Sep 25 | 135 days | Apr 12 – Apr 26 | May 10 – May 27 |
| Zone 5 | Apr 30 | Oct 5 | 160 days | Apr 2 – Apr 16 | Apr 30 – May 17 |
| Zone 6 | Apr 15 | Oct 15 | 185 days | Mar 18 – Apr 1 | Apr 15 – May 2 |
| Zone 7 | Apr 5 | Oct 25 | 200 days | Mar 8 – Mar 22 | Apr 5 – Apr 22 |
When to plant pumpkins in nearby states
Questions gardeners in Colorado ask
When is the best time to plant pumpkins in Colorado?
Plant pumpkin transplants outdoors in Colorado between May 5 and May 22. 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 pumpkin 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 5.
What is the latest I can plant pumpkins in Colorado?
About July 3. Pumpkins need at least 90 days to mature, and frost around October 1 ends the season, so later plantings risk being cut short. If you want ripe fruit for Halloween, the cut-off is earlier: see the Halloween dates on this page.
When will pumpkins planted in Colorado be ready to harvest?
Planted on time, pumpkins are usually ready from about August 10 to September 9, 90-120 days after planting.
When should I plant pumpkins in Colorado for Halloween?
Count back 90-120 days from October 1, Colorado's average first fall frost, which comes before Halloween: the latest sowing dates are June 3 to July 3. Sow a little earlier for a margin.
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.