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

Clark County, Wisconsin Zone 4b May

Top priorities for Clark County, Wisconsin gardeners in May

Your Clark County, Wisconsin garden is entering a new phase. Here's what's on the schedule for May and why each task matters now.

Avg. last frost May 13
Avg. first frost September 30
Soil temp (4") 54°F
Watering Low
Pest pressure Low
Daylight 14.6 hrs
  1. Direct-sow squash (summer)

    Mark the row. Birds and stray feet both have opinions about unmarked beds.

Get ahead of June
  • Transplants going out: squash (summer)
  • Starting indoors: 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.

Clark County, Wisconsin is in USDA Zone 4b. The average last spring frost is May 13 and the first fall frost is September 30, giving you a growing season of approximately 140 days.

At an elevation of 850 feet, Clark County receives approximately 39.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 82°F, so choose short-season varieties of Squash (Summer) to ensure they mature before fall.

Clark County, WI (Zone 4b) Short season
140 days
Last Spring Frost May 13
140 growing days
First Fall Frost September 30

Clark 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 (12 days to spare)
Start indoors: Mar 24 Transplant: May 26 🍅 Harvest: Jul 14 – Sep 15
Recommended (50%) ✓ Fits season (7 days to spare)
Start indoors: Apr 1 Transplant: Jun 3 🍅 Harvest: Jul 22 – Sep 23
Safe Start (90%) ✓ Fits season (13 days to spare)
Start indoors: Apr 9 Transplant: Jun 11 🍅 Harvest: Jul 30 – Oct 1

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 Clark County

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

Soil pH

Your soil pH (6.1–6.8) is within Squash (Summer)'s preferred range (6.0–7.5).

Soil Texture

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

Organic Matter

Organic matter is moderate (3.9%). Annual compost additions will help Squash (Summer).

How to Plant Squash (Summer)

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

Succession Planting Squash (Summer)

3
successive plantings in your 140-day season

Sow every 5.1 weeks. Last sowing by Jul 27 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.2″/week
Watering frequency Natural rainfall sufficient
Season total 0 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 1.8" 0" ❄️ Dormant
Feb 2" 0" ❄️ Dormant
Mar 2.6" 0" ❄️ Dormant
Apr 3.9" 0" ❄️ Dormant
May 4.3" 4.6" 0" ✅ Rainfall sufficient
Jun 4.3" 4.6" 0" ✅ Rainfall sufficient
Jul 4.3" 4.2" 0.1" 💧 Light watering
Aug 4.3" 4.2" 0.1" 💧 Light watering
Sep 4.3" 3.7" 0.6" 💧 Light watering
Oct 2.8" 0" ❄️ Dormant
Nov 3" 0" ❄️ Dormant
Dec 2.4" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Clark 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 ~632 GDD — county provides 1,610 GDD Excellent fit

Squash (Summer) Planting Timeline — Clark County, WI

Squash (Summer) Planting Calendar

Activity When Date Range
Start Indoors April 1 Apr 1 – Apr 15
Transplant Outdoors June 3 Jun 3 – Jun 17
Direct Sow May 27 May 27 – Jun 17
Harvest July 22 Jul 22 – Sep 23

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

45–65 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 4b

📆 Growing Season

140 days in Clark County

Growing Tips for Squash (Summer) in Clark County

Direct sow Squash (Summer) outdoors after May 13 in Clark County when soil has warmed and frost danger has passed.

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 Clark County, WI?

Clark County is in Zone 4b with an average last frost of May 13. Plan your Squash (Summer) planting based on this frost date — see the calendar above for exact timing.

What planting zone is Clark County, WI?

Clark County, Wisconsin is in USDA Hardiness Zone 4b. The average last spring frost is May 13 and first fall frost is September 30.

🌱

Your Clark County Garden Planner — Free

A 24-page printable planner built for Clark 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 Clark 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.