When to plant pumpkins in Montana
Montana’s average last spring frost is May 15, and the first fall frost typically arrives around September 15 — about 123 frost-free days (USDA zones 3a, 3b, 4a, 4b, 5a, 5b, 6a). Pumpkin needs 90–120 days to mature, which fits comfortably within Montana's growing season.
Montana 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 Montana: the short answer
For a spring planting, plant out May 15 – Jun 1, with seeds started indoors Apr 17 – May 1. Wait until the soil is at least 60°F and frost is over. For Halloween, count back 90–120 days from September 15: sow by May 18–Jun 17. 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 Montana, step by step
- Start seeds indoors (Apr 17 – May 1). 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 15 – Jun 1). 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 20 – Sep 19). 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 Montana’s average frost dates. More in the full pumpkin growing guide.
Planting pumpkins in Montana for Halloween
Spring dates above suit a long season. If you want fruit ready for Halloween, count back from Montana's average first fall frost (September 15), 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 | May 18 | slowest types (giants) |
| 100 days | June 7 | jack-o'-lantern and pie types (University of Arkansas variety table) |
| 90 days | June 17 | 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 Montana
Montana spans USDA zones 3a, 3b, 4a, 4b, 5a, 5b, 6a. 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.
When to plant pumpkins in nearby states
Questions gardeners in Montana ask
When is the best time to plant pumpkins in Montana?
Plant pumpkin transplants outdoors in Montana between May 15 and June 1. That timing is set by Montana's average last spring frost of May 15; Montana spans several climates, so cooler and higher parts of the state run later.
When should I start pumpkin seeds indoors in Montana?
Start seeds indoors between April 17 and May 1, about 3 weeks before the last frost, so the seedlings are ready to plant out from May 15.
What is the latest I can plant pumpkins in Montana?
About June 17. Pumpkins need at least 90 days to mature, and frost around September 15 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 Montana be ready to harvest?
Planted on time, pumpkins are usually ready from about August 20 to September 19, 90-120 days after planting.
When should I plant pumpkins in Montana for Halloween?
Count back 90-120 days from September 15, Montana's average first fall frost, which comes before Halloween: the latest sowing dates are May 18 to June 17. Sow a little earlier for a margin.
When is the last frost in Montana?
On average around May 15, with the first fall frost around September 15 - about 123 frost-free days. Your town may differ by two weeks or more.