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When to Plant Kabocha in Williamson County, IL

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.

Williamson County, Illinois is in USDA Zone 6b. The average last spring frost is April 10 and the first fall frost is October 20, giving you a growing season of approximately 193 days.

At an elevation of 1,253 feet, Williamson County receives approximately 38.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 91ยฐF, providing good warmth for Kabocha during the growing season.

Williamson County, IL (Zone 6b) Moderate season
193 days
Last Spring Frost April 10
193 growing days
First Fall Frost October 20

Williamson County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (58 days to spare)
Start indoors: Mar 1 Transplant: Apr 19 🍅 Harvest: Jul 19 – Aug 16
Recommended (50%) ✓ Fits season (60 days to spare)
Start indoors: Mar 6 Transplant: Apr 24 🍅 Harvest: Jul 24 – Aug 21
Safe Start (90%) ✓ Fits season (59 days to spare)
Start indoors: Mar 18 Transplant: May 6 🍅 Harvest: Aug 5 – Sep 2

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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 339 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Kabocha needs ~1,688 GDD — county provides 3,522 GDD Excellent fit

Kabocha Planting Timeline โ€” Williamson County, IL

Kabocha Planting Calendar

Activity When Date Range
Start Indoors March 6 Mar 6 โ€“ Mar 20
Transplant Outdoors April 24 Apr 24 โ€“ May 8
Direct Sow April 17 Apr 17 โ€“ May 8
Harvest July 24 Jul 24 โ€“ Aug 21

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

85โ€“100 days

Soil pH

6 โ€“ 7.5

USDA Zone

Zone 6b

Growing Season

193 days

Growing Tips for Williamson County

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

Level Up Your Garden

Frequently Asked Questions

When should I plant Kabocha in Williamson County, IL?

Williamson County is in Zone 6b with an average last frost of April 10. Plan your Kabocha planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Williamson County, IL?

Williamson County, Illinois is in USDA Hardiness Zone 6b. The average last spring frost is April 10 and first fall frost is October 20.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Williamson County gardeners in Zone 6b organize planting dates, track what's growing, and never miss a planting window.

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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 Williamson County, IL. Local conditions may vary. Last updated: April 2026.