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When to Plant Kabocha in McHenry 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.

McHenry County, Illinois is in USDA Zone 5a. The average last spring frost is April 18 and the first fall frost is October 20, giving you a growing season of approximately 185 days.

At an elevation of 640 feet, McHenry County receives approximately 39.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84ยฐF, so choose short-season varieties of Kabocha to ensure they mature before fall.

McHenry County, IL (Zone 5a) Moderate season
185 days
Last Spring Frost April 18
185 growing days
First Fall Frost October 20

McHenry County Soil Profile

Soil Type

Silt Loam

Soil pH

5.9-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (48 days to spare)
Start indoors: Mar 9 Transplant: Apr 27 🍅 Harvest: Jul 27 – Aug 24
Recommended (50%) ✓ Fits season (52 days to spare)
Start indoors: Mar 14 Transplant: May 2 🍅 Harvest: Aug 1 – Aug 29
Safe Start (90%) ✓ Fits season (51 days to spare)
Start indoors: Mar 30 Transplant: May 18 🍅 Harvest: Aug 17 – Sep 14

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
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 208 gal / 100 sq ft
Drought risk

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

Kabocha needs ~1,202 GDD — county provides 2,405 GDD Excellent fit

Kabocha Planting Timeline โ€” McHenry County, IL

Kabocha Planting Calendar

Activity When Date Range
Start Indoors March 14 Mar 14 โ€“ Mar 28
Transplant Outdoors May 2 May 2 โ€“ May 16
Direct Sow April 25 Apr 25 โ€“ May 16
Harvest August 1 Aug 1 โ€“ Aug 29

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March Start Indoors
April Direct Sow
May Transplant Outdoors Direct Sow
June โ€”
July โ€”
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 5a

Growing Season

185 days

Growing Tips for McHenry 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 McHenry County, IL?

McHenry County is in Zone 5a with an average last frost of April 18. Plan your Kabocha planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is McHenry County, IL?

McHenry County, Illinois is in USDA Hardiness Zone 5a. The average last spring frost is April 18 and first fall frost is October 20.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help McHenry County gardeners in Zone 5a 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 McHenry County, IL. Local conditions may vary. Last updated: April 2026.