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When to Plant Zucchini in Clay 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.

Clay County, Illinois is in USDA Zone 6a. The average last spring frost is April 14 and the first fall frost is October 17, giving you a growing season of approximately 186 days.

At an elevation of 1,105 feet, Clay County receives approximately 34.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85ยฐF, providing good warmth for Zucchini during the growing season.

Clay County, IL (Zone 6a) Moderate season
186 days
Last Spring Frost April 14
186 growing days
First Fall Frost October 17

Clay County Soil Profile

Soil Type

Silt Loam

Soil pH

6-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (66 days to spare)
Start indoors: Mar 5 Transplant: Apr 23 🍅 Harvest: Jun 11 – Aug 6
Recommended (50%) ✓ Fits season (67 days to spare)
Start indoors: Mar 10 Transplant: Apr 28 🍅 Harvest: Jun 16 – Aug 11
Safe Start (90%) ✓ Fits season (67 days to spare)
Start indoors: Mar 23 Transplant: May 11 🍅 Harvest: Jun 29 – Aug 24

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 Clay County

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

Soil pH

Your soil pH (6.0โ€“6.9) is within Zucchini's preferred range (6.0โ€“7.5).

Soil Texture

The silt loam soil in Clay County is excellent for Zucchini โ€” good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (4.1%) โ€” Zucchini will thrive.

How to Plant Zucchini

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

Succession Planting Zucchini

4
successive plantings in your 186-day season

Sow every 5.1 weeks. Last sowing by Aug 18 to harvest before frost.

Plant Water Budget

Plant needs
1.2″/week
Rainfall provides
0.8″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 818 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Zucchini

Zucchini needs approximately 1.2 inches of water per week (5.2" per month). Here's how your county's rainfall compares month by month.

Month Zucchini Needs Rainfall You Supplement Action
Jan โ€” 1.5" 0" โ„๏ธ Dormant
Feb โ€” 1.9" 0" โ„๏ธ Dormant
Mar โ€” 2.8" 0" โ„๏ธ Dormant
Apr 5.2" 3.8" 1.4" ๐Ÿ’ง Light watering
May 5.2" 3.8" 1.4" ๐Ÿ’ง Light watering
Jun 5.2" 4.1" 1.1" ๐Ÿ’ง Light watering
Jul 5.2" 3.7" 1.5" ๐Ÿ’ง Light watering
Aug 5.2" 3.5" 1.7" ๐Ÿ’ง Light watering
Sep 5.2" 2.8" 2.4" ๐Ÿ’ง Light watering
Oct 5.2" 2.6" 2.6" ๐Ÿšฟ Regular watering
Nov โ€” 2.3" 0" โ„๏ธ Dormant
Dec โ€” 2.2" 0" โ„๏ธ Dormant

Water needs are for active growing months only (Aprโ€“Oct in Clay County). Supplement amounts are based on average rainfall โ€” actual needs vary with temperature, soil, and mulching.

Zucchini 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" โ€” every day above 50ยฐF 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.

Zucchini needs ~722 GDD — county provides 2,557 GDD Excellent fit

Zucchini Planting Timeline โ€” Clay County, IL

Zucchini Planting Calendar

Activity When Date Range
Start Indoors March 10 Mar 10 โ€“ Mar 24
Transplant Outdoors April 28 Apr 28 โ€“ May 12
Direct Sow April 21 Apr 21 โ€“ May 12
Harvest June 16 Jun 16 โ€“ Aug 11

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

โ˜€๏ธ Sun

Full Sun (6-8+ hours)

๐Ÿ’ง Water

1.2"/week ยท 1-2 times/week

๐Ÿ“… Days to Maturity

45โ€“60 days

๐Ÿงช Soil pH

Needs 6โ€“7.5 ยท Your soil: ideal

๐Ÿ—บ๏ธ USDA Zone

Zone 6a

๐Ÿ“† Growing Season

186 days in Clay County

Growing Tips for Zucchini in Clay County

Direct sow Zucchini outdoors after April 14 in Clay County when soil has warmed and frost danger has passed.

Your generous 186.0-day season in Clay County allows multiple plantings of Zucchini. Sow every 22.0 days for continuous harvest.

Common pests for Zucchini 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. 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

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Zucchini in Clay County, IL?

Clay County is in Zone 6a with an average last frost of April 14. Plan your Zucchini planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Clay County, IL?

Clay County, Illinois is in USDA Hardiness Zone 6a. The average last spring frost is April 14 and first fall frost is October 17.

๐ŸŒฑ

Plan Your Garden with Confidence

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

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Clay County, IL. Local conditions may vary. Last updated: April 2026.