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When to Plant Butternut Squash in Milwaukee County, WI

Milwaukee County, Wisconsin Zone 6a May

Your May game plan for Milwaukee County, Wisconsin

May is a pivotal month for Milwaukee County, Wisconsin gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost April 27
Avg. first frost October 11
Soil temp (4") 56°F
Watering Low
Pest pressure Low
Daylight 14.5 hrs
  1. Harden off and plant butternut squash

    Frost risk is low now in Milwaukee County, Wisconsin. If you've been covering beds overnight, you can stop.

  2. Put butternut squash seeds straight in the ground

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

June will be here before you know it — start on
  • 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.

Milwaukee County, Wisconsin is in USDA Zone 6a. The average last spring frost is April 27 and the first fall frost is October 11, giving you a growing season of approximately 167 days.

At an elevation of 1,100 feet, Milwaukee County receives approximately 38.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Butternut Squash during the growing season.

Milwaukee County, WI (Zone 6a) Moderate season
167 days
Last Spring Frost April 27
167 growing days
First Fall Frost October 11

Milwaukee County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (26 days to spare)
Start indoors: Mar 18 Transplant: May 6 🍅 Harvest: Aug 5 – Sep 9
Recommended (50%) ✓ Fits season (27 days to spare)
Start indoors: Mar 23 Transplant: May 11 🍅 Harvest: Aug 10 – Sep 14
Safe Start (90%) ✓ Fits season (25 days to spare)
Start indoors: Apr 8 Transplant: May 27 🍅 Harvest: Aug 26 – Sep 30

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 Milwaukee County

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

Soil pH

Your soil pH (6.1–6.8) is within Butternut Squash's preferred range (6.0–7.0).

Soil Texture

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

Organic Matter

Organic matter is excellent (5.0%) — Butternut Squash will thrive.

How to Plant Butternut Squash

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

Plant Water Budget

Plant needs
1.1″/week
Rainfall provides
1.0″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 203 gal / 100 sq ft

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 1.7" 0" ❄️ Dormant
Feb 1.7" 0" ❄️ Dormant
Mar 2.5" 0" ❄️ Dormant
Apr 4.8" 4.2" 0.6" 💧 Light watering
May 4.8" 4" 0.8" 💧 Light watering
Jun 4.8" 4.3" 0.5" 💧 Light watering
Jul 4.8" 4.5" 0.3" 💧 Light watering
Aug 4.8" 4" 0.8" 💧 Light watering
Sep 4.8" 3.2" 1.6" 💧 Light watering
Oct 4.8" 2.8" 2" 💧 Light watering
Nov 3" 0" ❄️ Dormant
Dec 2.3" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Milwaukee 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 ~1,414 GDD — county provides 2,421 GDD Excellent fit

Butternut Squash Planting Timeline — Milwaukee County, WI

Butternut Squash Planting Calendar

Activity When Date Range
Start Indoors March 23 Mar 23 – Apr 6
Transplant Outdoors May 11 May 11 – May 25
Direct Sow May 4 May 4 – May 25
Harvest August 10 Aug 10 – Sep 14

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.1"/week · Only during dry spells

📅 Days to Maturity

85–110 days

🧪 Soil pH

Needs 6–7 · Your soil: ideal

🗺️ USDA Zone

Zone 6a

📆 Growing Season

167 days in Milwaukee County

Growing Tips for Butternut Squash in Milwaukee County

Direct sow Butternut Squash outdoors after April 27 in Milwaukee 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.

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 Milwaukee County, WI?

Milwaukee County is in Zone 6a with an average last frost of April 27. Plan your Butternut Squash planting based on this frost date — see the calendar above for exact timing.

What planting zone is Milwaukee County, WI?

Milwaukee County, Wisconsin is in USDA Hardiness Zone 6a. The average last spring frost is April 27 and first fall frost is October 11.

🌱

Your Milwaukee County Garden Planner — Free

A 24-page printable planner built for Milwaukee County (Zone 6a). 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 Milwaukee County, WI. 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.