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When to Plant Squash (Summer) in Waukesha County, WI

Waukesha County, Wisconsin Zone 5b May

May to-do list for Waukesha County, Wisconsin

Your garden in Waukesha County, Wisconsin is working on a schedule, even when you're not. Here's where you should be this May.

Avg. last frost April 27
Avg. first frost October 12
Soil temp (4") 56°F
Watering Low
Pest pressure Low
Daylight 14.5 hrs
  1. Harden off and plant squash (summer)

    Pinch off the lowest leaves on each seedling before you plant — it reduces water loss while the roots catch up.

  2. Seed squash (summer) outdoors

    Rake a smooth bed, make a shallow furrow, drop seeds at the spacing on the packet, water gently, walk away.

Get ahead of June
  • Starting indoors: squash (summer)
  • First harvests: squash (summer)

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Summer squash includes zucchini, yellow crookneck, and pattypan varieties that are harvested young and tender. They are prolific producers in warm weather.

Waukesha County, Wisconsin is in USDA Zone 5b. The average last spring frost is April 27 and the first fall frost is October 12, giving you a growing season of approximately 168 days.

At an elevation of 1,352 feet, Waukesha County receives approximately 37.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Squash (Summer) to ensure they mature before fall.

Waukesha County, WI (Zone 5b) Moderate season
168 days
Last Spring Frost April 27
168 growing days
First Fall Frost October 12
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Waukesha County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (41 days to spare)
Start indoors: Mar 19 Transplant: May 7 🍅 Harvest: Jun 25 – Aug 27
Recommended (50%) ✓ Fits season (42 days to spare)
Start indoors: Mar 23 Transplant: May 11 🍅 Harvest: Jun 29 – Aug 31
Safe Start (90%) ✓ Fits season (40 days to spare)
Start indoors: Apr 8 Transplant: May 27 🍅 Harvest: Jul 15 – Sep 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 Waukesha County

How your county's soil matches Squash (Summer)'s growing requirements.

Soil pH

Your soil pH (6.1–7.3) is within Squash (Summer)'s preferred range (6.0–7.5).

Soil Texture

The silt loam soil in Waukesha County is excellent for Squash (Summer) — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Drainage is adequate for Squash (Summer).

Organic Matter

Organic matter is excellent (4.2%) — Squash (Summer) will thrive.

How to Plant Squash (Summer)

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

Succession Planting Squash (Summer)

4
successive plantings in your 168-day season

Sow every 5.1 weeks. Last sowing by Aug 08 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 549 gal / 100 sq ft

Monthly Watering Guide for Squash (Summer)

Squash (Summer) needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Squash (Summer) Needs Rainfall You Supplement Action
Jan 1.7" 0" ❄️ Dormant
Feb 1.8" 0" ❄️ Dormant
Mar 2.8" 0" ❄️ Dormant
Apr 4.3" 3.4" 0.9" 💧 Light watering
May 4.3" 4.3" 0" ✅ Rainfall sufficient
Jun 4.3" 4.5" 0" ✅ Rainfall sufficient
Jul 4.3" 4" 0.3" 💧 Light watering
Aug 4.3" 3.7" 0.6" 💧 Light watering
Sep 4.3" 3.2" 1.1" 💧 Light watering
Oct 4.3" 3.2" 1.1" 💧 Light watering
Nov 2.6" 0" ❄️ Dormant
Dec 2" 0" ❄️ Dormant

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

Squash (Summer) 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.

Squash (Summer) needs ~674 GDD — county provides 2,058 GDD Excellent fit

Squash (Summer) Planting Timeline — Waukesha County, WI

Squash (Summer) 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 June 29 Jun 29 – Aug 31

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 Harvest
July Harvest
August Harvest
September
October
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

45–65 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 5b

📆 Growing Season

168 days in Waukesha County

Growing Tips for Squash (Summer) in Waukesha County

Direct sow Squash (Summer) outdoors after April 27 in Waukesha County when soil has warmed and frost danger has passed.

Your generous 168.0-day season in Waukesha County allows multiple plantings of Squash (Summer). Sow every 22.0 days for continuous harvest.

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

General growing tips

Direct sow after last frost on mounds. Harvest frequently when fruits are 6-8 inches for best texture. Check plants daily as they grow rapidly in summer heat.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Squash (Summer) in Waukesha County, WI?

Waukesha County is in Zone 5b with an average last frost of April 27. Plan your Squash (Summer) planting based on this frost date — see the calendar above for exact timing.

What planting zone is Waukesha County, WI?

Waukesha County, Wisconsin is in USDA Hardiness Zone 5b. The average last spring frost is April 27 and first fall frost is October 12.

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Your Waukesha County Garden Planner — Free

A 24-page printable planner built for Waukesha County (Zone 5b). 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 Waukesha 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.