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When to Plant Kabocha in Walworth County, WI

Walworth County, Wisconsin Zone 5b May

What to do in May

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Walworth County, Wisconsin.

Avg. last frost April 26
Avg. first frost October 13
Soil temp (4") 56°F
Watering Low
Pest pressure Low
Daylight 14.4 hrs
  1. Move kabocha from tray to bed

    Pick a cloudy afternoon or evening to plant. Less transplant shock, and your seedlings will barely blink.

  2. Seed kabocha outdoors

    Thin ruthlessly once seedlings are up. Crowded roots mean smaller crops from every plant.

  3. Fire up the seed-starting tray: kabocha

    A seed-starting mix and a sunny window (or a grow light) are all you need. Keep soil warm — around 70°F — for fast germination.

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Kabocha is a Japanese winter squash with an exceptionally sweet, dense, chestnut-like flesh and dark green skin. It is a favorite in Asian cuisine for its rich, dry texture.

Walworth County, Wisconsin is in USDA Zone 5b. The average last spring frost is April 26 and the first fall frost is October 13, giving you a growing season of approximately 170 days.

At an elevation of 1,101 feet, Walworth County receives approximately 39.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Kabocha during the growing season.

Walworth County, WI (Zone 5b) Moderate season
170 days
Last Spring Frost April 26
170 growing days
First Fall Frost October 13

Walworth County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (36 days to spare)
Start indoors: Mar 18 Transplant: May 6 🍅 Harvest: Aug 5 – Sep 2
Recommended (50%) ✓ Fits season (37 days to spare)
Start indoors: Mar 22 Transplant: May 10 🍅 Harvest: Aug 9 – Sep 6
Safe Start (90%) ✓ Fits season (35 days to spare)
Start indoors: Apr 7 Transplant: May 26 🍅 Harvest: Aug 25 – Sep 22

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 Walworth County

How your county's soil matches Kabocha's growing requirements.

Soil pH

Your soil pH (6.2–6.9) is within Kabocha's preferred range (6.0–7.5).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.4%) — Kabocha will thrive.

How to Plant Kabocha

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

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 39 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Kabocha

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

Month Kabocha Needs Rainfall You Supplement Action
Jan 1.9" 0" ❄️ Dormant
Feb 1.8" 0" ❄️ Dormant
Mar 2.5" 0" ❄️ Dormant
Apr 4.3" 3.8" 0.5" 💧 Light watering
May 4.3" 4.2" 0.1" 💧 Light watering
Jun 4.3" 4.7" 0" ✅ Rainfall sufficient
Jul 4.3" 4.9" 0" ✅ Rainfall sufficient
Aug 4.3" 4.1" 0.2" 💧 Light watering
Sep 4.3" 4.2" 0.1" 💧 Light watering
Oct 4.3" 2.9" 1.4" 💧 Light watering
Nov 2.7" 0" ❄️ Dormant
Dec 2" 0" ❄️ Dormant

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

Kabocha 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.

Kabocha needs ~1,411 GDD — county provides 2,592 GDD Excellent fit

Kabocha Planting Timeline — Walworth County, WI

Kabocha Planting Calendar

Activity When Date Range
Start Indoors March 22 Mar 22 – Apr 5
Transplant Outdoors May 10 May 10 – May 24
Direct Sow May 3 May 3 – May 24
Harvest August 9 Aug 9 – Sep 6

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"/week · Only during dry spells

📅 Days to Maturity

85–100 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 5b

📆 Growing Season

170 days in Walworth County

Growing Tips for Kabocha in Walworth County

Direct sow Kabocha outdoors after April 26 in Walworth County when soil has warmed and frost danger has passed.

Common pests for Kabocha 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 frost or start indoors. Harvest when the skin is hard and dull. The stem should be dry and corky. Stores well for 3-4 months in a cool, dry place.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Kabocha in Walworth County, WI?

Walworth County is in Zone 5b with an average last frost of April 26. Plan your Kabocha planting based on this frost date — see the calendar above for exact timing.

What planting zone is Walworth County, WI?

Walworth County, Wisconsin is in USDA Hardiness Zone 5b. The average last spring frost is April 26 and first fall frost is October 13.

🌱

Your Walworth County Garden Planner — Free

A 24-page printable planner built for Walworth 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 Walworth 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.