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When to Plant Butternut Squash in Treasure County, MT

Treasure County, Montana Zone 4b May

Your May planting checklist for Treasure County, Montana

Here's what deserves your attention in Treasure County, Montana this month. Everything below is tailored to Zone 4b and timed around your local frost dates.

Avg. last frost May 11
Avg. first frost October 1
Soil temp (4") 34°F
Watering High
Pest pressure Low
Daylight 14.8 hrs
  1. Direct-sow butternut squash

    Succession planting is the secret here. Put in a row now, another in 2 weeks, a third in 4.

Before June arrives, get these ready
  • Transplants going out: butternut squash
  • Starting indoors: butternut squash

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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.

Treasure County, Montana is in USDA Zone 4b. The average last spring frost is May 11 and the first fall frost is October 1, giving you a growing season of approximately 143 days.

At an elevation of 6,726 feet, Treasure County receives approximately 17.1 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Butternut Squash to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Butternut Squash successfully. Mulch heavily to conserve soil moisture.

Treasure County, MT (Zone 4b) Short season
143 days
Last Spring Frost May 11
143 growing days
First Fall Frost October 1

Treasure County Soil Profile

Soil Type

Loam

Soil pH

6.5-8.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 24 Transplant: May 26 🍅 Harvest: Aug 25 – Sep 29
Recommended (50%) ✗ May not fit
Start indoors: Mar 30 Transplant: Jun 1 🍅 Harvest: Aug 31 – Oct 5
Safe Start (90%) ✗ May not fit
Start indoors: Apr 10 Transplant: Jun 12 🍅 Harvest: Sep 11 – Oct 16

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.

Soil Compatibility in Treasure County

How your county's soil matches Butternut Squash's growing requirements.

Soil pH

Your soil pH (6.5–8.3) is more alkaline than Butternut Squash prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Treasure County is excellent for Butternut Squash — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.1%). Annual compost additions will help Butternut Squash.

How to Plant Butternut Squash

1"
Planting Depth
30"
Between Plants
42"
Between Rows

Plant Water Budget

Plant needs
1.1″/week
Rainfall provides
0.5″/week
You supply
0.7″/week
Watering frequency 2-3 times/week
Season total 913 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Butternut Squash

Butternut Squash needs approximately 1.1 inches of water per week (4.8" per month). Here's how your county's rainfall compares month by month.

Month Butternut Squash Needs Rainfall You Supplement Action
Jan 1.2" 0" ❄️ Dormant
Feb 1" 0" ❄️ Dormant
Mar 1.3" 0" ❄️ Dormant
Apr 1.9" 0" ❄️ Dormant
May 4.8" 1.9" 2.9" 🚿 Regular watering
Jun 4.8" 1.3" 3.5" 🚿 Regular watering
Jul 4.8" 1.6" 3.2" 🚿 Regular watering
Aug 4.8" 1.5" 3.3" 🚿 Regular watering
Sep 4.8" 1.5" 3.3" 🚿 Regular watering
Oct 4.8" 1.6" 3.2" 🚿 Regular watering
Nov 1.3" 0" ❄️ Dormant
Dec 0.9" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Treasure County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Butternut Squash Heat Requirements (GDD)

What are Growing Degree Days (GDD)?

Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.

Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.

Butternut Squash needs ~1,268 GDD — county provides 1,859 GDD Excellent fit

Butternut Squash Planting Timeline — Treasure County, MT

Butternut Squash Planting Calendar

Activity When Date Range
Start Indoors March 30 Mar 30 – Apr 13
Transplant Outdoors June 1 Jun 1 – Jun 15
Direct Sow May 25 May 25 – Jun 15
Harvest August 31 Aug 31 – Oct 5

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.1"/week · 2-3 times/week

📅 Days to Maturity

85–110 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 4b

📆 Growing Season

143 days in Treasure County

Growing Tips for Butternut Squash in Treasure County

Direct sow Butternut Squash outdoors after May 11 in Treasure County when soil has warmed and frost danger has passed.

Common pests for Butternut Squash in this region include squash vine borer and cucumber beetles. Use row covers early in the season and inspect plants weekly.

Treasure County receives only 17" of rain annually. Butternut Squash needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

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

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Butternut Squash in Treasure County, MT?

Treasure County is in Zone 4b with an average last frost of May 11. Plan your Butternut Squash planting based on this frost date — see the calendar above for exact timing.

What planting zone is Treasure County, MT?

Treasure County, Montana is in USDA Hardiness Zone 4b. The average last spring frost is May 11 and first fall frost is October 1.

🌱

Your Treasure County Garden Planner — Free

A 24-page printable planner built for Treasure County (Zone 4b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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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 Treasure County, MT. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.