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When to Plant Zucchini in Lake 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.

Lake County, Illinois is in USDA Zone 5b. The average last spring frost is April 21 and the first fall frost is October 20, giving you a growing season of approximately 182 days.

At an elevation of 1,080 feet, Lake County receives approximately 33.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83ยฐF, so choose short-season varieties of Zucchini to ensure they mature before fall.

Lake County, IL (Zone 5b) Moderate season
182 days
Last Spring Frost April 21
182 growing days
First Fall Frost October 20

Lake 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 (59 days to spare)
Start indoors: Mar 12 Transplant: Apr 30 🍅 Harvest: Jun 18 – Aug 13
Recommended (50%) ✓ Fits season (63 days to spare)
Start indoors: Mar 17 Transplant: May 5 🍅 Harvest: Jun 23 – Aug 18
Safe Start (90%) ✓ Fits season (61 days to spare)
Start indoors: Apr 4 Transplant: May 23 🍅 Harvest: Jul 11 – Sep 5

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
0.3″/week
Watering frequency Only during dry spells
Season total 441 gal / 100 sq ft
Drought risk

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

Zucchini needs ~643 GDD — county provides 2,229 GDD Excellent fit

Zucchini Planting Timeline โ€” Lake County, IL

Zucchini Planting Calendar

Activity When Date Range
Start Indoors March 17 Mar 17 โ€“ Mar 31
Transplant Outdoors May 5 May 5 โ€“ May 19
Direct Sow April 28 Apr 28 โ€“ May 19
Harvest June 23 Jun 23 โ€“ Aug 18

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 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 5b

Growing Season

182 days

Growing Tips for Lake 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 Lake County, IL?

Lake County is in Zone 5b with an average last frost of April 21. Plan your Zucchini planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Lake County, IL?

Lake County, Illinois is in USDA Hardiness Zone 5b. The average last spring frost is April 21 and first fall frost is October 20.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Lake County gardeners in Zone 5b organize planting dates, track what's growing, and never miss a planting window.

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