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When to Plant Pumpkin in Missoula County, MT

Pumpkins are large-fruited squash varieties grown for eating, decoration, and seed production. They require ample space and a long, warm growing season.

Missoula County, Montana is in USDA Zone 5a. The average last spring frost is May 14 and the first fall frost is September 23, giving you a growing season of approximately 132 days.

At an elevation of 8,019 feet, Missoula County receives approximately 15.9 inches of rainfall annually with predominantly loam soil. Summer highs average 87ยฐF, providing good warmth for Pumpkin during the growing season. With low rainfall, drip irrigation is essential for growing Pumpkin successfully. Mulch heavily to conserve soil moisture.

Missoula County, MT (Zone 5a) Short season
132 days
Last Spring Frost May 14
132 growing days
First Fall Frost September 23

Missoula County Soil Profile

Soil Type

Loam

Soil pH

6.2-7.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 3 Transplant: May 22 🍅 Harvest: Aug 21 – Oct 9
Recommended (50%) ✗ May not fit
Start indoors: Apr 9 Transplant: May 28 🍅 Harvest: Aug 27 – Oct 15
Safe Start (90%) ✗ May not fit
Start indoors: Apr 30 Transplant: Jun 18 🍅 Harvest: Sep 17 – Nov 5

Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.5″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 697 gal / 100 sq ft
Drought risk

Water stress score is 8/10 โ€” consider drought-tolerant varieties and mulching

Pumpkin needs ~1,563 GDD — county provides 2,013 GDD Good fit

Pumpkin Planting Timeline โ€” Missoula County, MT

Pumpkin Planting Calendar

Activity When Date Range
Start Indoors April 9 Apr 9 โ€“ Apr 23
Transplant Outdoors May 28 May 28 โ€“ Jun 11
Direct Sow May 21 May 21 โ€“ Jun 11
Harvest August 27 Aug 27 โ€“ Oct 15

Plant 1" deep ยท 30" apart ยท Rows 42" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April Start Indoors
May Transplant Outdoors Direct Sow
June Transplant Outdoors Direct Sow
July โ€”
August Harvest
September Harvest
October Harvest
November โ€”
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

85โ€“120 days

Soil pH

6 โ€“ 7.5

USDA Zone

Zone 5a

Growing Season

132 days

Growing Tips for Missoula County

Direct sow on mounds after last frost. Allow 6-10 feet between plants. Slip a board under developing fruit to prevent rot. Harvest when rind is hard and deep in color.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Level Up Your Garden

Frequently Asked Questions

When should I plant Pumpkin in Missoula County, MT?

Missoula County is in Zone 5a with an average last frost of May 14. Plan your Pumpkin planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Missoula County, MT?

Missoula County, Montana is in USDA Hardiness Zone 5a. The average last spring frost is May 14 and first fall frost is September 23.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Missoula County gardeners in Zone 5a organize planting dates, track what's growing, and never miss a planting window.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Missoula County, MT. Local conditions may vary. Last updated: April 2026.