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When to Plant Butternut Squash in Millard County, UT

Butternut squash is a popular winter squash with a long neck, small seed cavity, and sweet, nutty orange flesh. It stores exceptionally well for months.

Millard County, Utah is in USDA Zone 5b. The average last spring frost is May 16 and the first fall frost is September 30, giving you a growing season of approximately 137 days.

At an elevation of 6,525 feet, Millard County receives approximately 24 inches of rainfall annually with predominantly loam soil. Summer highs average 84ยฐF, so choose short-season varieties of Butternut Squash to ensure they mature before fall.

Millard County, UT (Zone 5b) Short season
137 days
Last Spring Frost May 16
137 growing days
First Fall Frost September 30

Millard County Soil Profile

Soil Type

Loam

Soil pH

6.5-8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 2 Transplant: May 21 🍅 Harvest: Aug 20 – Sep 24
Recommended (50%) ✗ May not fit
Start indoors: Apr 11 Transplant: May 30 🍅 Harvest: Aug 29 – Oct 3
Safe Start (90%) ✗ May not fit
Start indoors: May 5 Transplant: Jun 23 🍅 Harvest: Sep 22 – Oct 27

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
0.7″/week
You supply
0.3″/week
Watering frequency 1-2 times/week
Season total 387 gal / 100 sq ft
Drought risk

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

Butternut Squash needs ~1,268 GDD — county provides 1,781 GDD Excellent fit

Butternut Squash Planting Timeline โ€” Millard County, UT

Butternut Squash Planting Calendar

Activity When Date Range
Start Indoors April 11 Apr 11 โ€“ Apr 25
Transplant Outdoors May 30 May 30 โ€“ Jun 13
Direct Sow May 23 May 23 โ€“ Jun 13
Harvest August 29 Aug 29 โ€“ Oct 3

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€“110 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 5b

Growing Season

137 days

Growing Tips for Millard County

Start seeds indoors 3 weeks early or direct sow after frost. Allow 6-8 feet for sprawling vines. Harvest when the skin is hard and uniformly tan. Cure in the sun for 10 days.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Level Up Your Garden

Frequently Asked Questions

When should I plant Butternut Squash in Millard County, UT?

Millard County is in Zone 5b with an average last frost of May 16. Plan your Butternut Squash planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Millard County, UT?

Millard County, Utah is in USDA Hardiness Zone 5b. The average last spring frost is May 16 and first fall frost is September 30.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Millard County gardeners in Zone 5b 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 Millard County, UT. Local conditions may vary. Last updated: April 2026.