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When to Plant Zucchini in Clinton County, IL

Zucchini is an incredibly prolific summer squash that can produce an abundance of fruit from just a few plants. It is versatile in the kitchen from grilling to baking.

Clinton County, Illinois is in USDA Zone 6a. The average last spring frost is April 10 and the first fall frost is October 19, giving you a growing season of approximately 192 days.

At an elevation of 1,142 feet, Clinton County receives approximately 38.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85ยฐF, providing good warmth for Zucchini during the growing season.

Clinton County, IL (Zone 6a) Moderate season
192 days
Last Spring Frost April 10
192 growing days
First Fall Frost October 19

Clinton County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (73 days to spare)
Start indoors: Feb 28 Transplant: Apr 18 🍅 Harvest: Jun 6 – Aug 1
Recommended (50%) ✓ Fits season (73 days to spare)
Start indoors: Mar 6 Transplant: Apr 24 🍅 Harvest: Jun 12 – Aug 7
Safe Start (90%) ✓ Fits season (75 days to spare)
Start indoors: Mar 15 Transplant: May 3 🍅 Harvest: Jun 21 – Aug 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.

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 342 gal / 100 sq ft
Drought risk

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

Zucchini needs ~722 GDD — county provides 2,640 GDD Excellent fit

Zucchini Planting Timeline โ€” Clinton County, IL

Zucchini 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 June 12 Jun 12 โ€“ Aug 7

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 Harvest
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

45โ€“60 days

Soil pH

6 โ€“ 7.5

USDA Zone

Zone 6a

Growing Season

192 days

Growing Tips for Clinton County

Direct sow after last frost. Harvest when fruits are 6-8 inches long for best flavor and texture. Check plants daily in summer as fruits can double in size overnight.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Level Up Your Garden

Frequently Asked Questions

When should I plant Zucchini in Clinton County, IL?

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

What planting zone is Clinton County, IL?

Clinton County, Illinois is in USDA Hardiness Zone 6a. The average last spring frost is April 10 and first fall frost is October 19.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Clinton County gardeners in Zone 6a 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 Clinton County, IL. Local conditions may vary. Last updated: April 2026.