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When to Plant Potatoes in Lake County, IL

Potatoes are a versatile staple crop that produces tubers underground. They come in hundreds of varieties with varying colors, textures, and maturity dates.

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 Potatoes 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 (24 days to spare)
Start indoors: Feb 19 Transplant: Apr 30 🍅 Harvest: Jul 9 – Sep 17
Recommended (50%) ✓ Fits season (28 days to spare)
Start indoors: Feb 24 Transplant: May 5 🍅 Harvest: Jul 14 – Sep 22
Safe Start (90%) ✓ Fits season (26 days to spare)
Start indoors: Mar 14 Transplant: May 23 🍅 Harvest: Aug 1 – Oct 10

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

Potatoes needs ~1,164 GDD — county provides 2,229 GDD Excellent fit

Potatoes Planting Timeline โ€” Lake County, IL

Potatoes Planting Calendar

Activity When Date Range
Start Indoors February 24 Feb 24 โ€“ Mar 10
Transplant Outdoors May 5 May 5 โ€“ May 19
Direct Sow April 28 Apr 28 โ€“ May 19
Harvest July 14 Jul 14 โ€“ Sep 22

Plant 1" deep ยท 15" apart ยท Rows 24" apart

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

70โ€“120 days

Soil pH

5 โ€“ 6.5

USDA Zone

Zone 5b

Growing Season

182 days

Growing Tips for Lake County

Plant seed potatoes (not grocery store potatoes) 4 inches deep in spring. Hill soil around stems as plants grow to prevent greening. Stop watering when plants die back.

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes
  • Cucumber
  • Squash Summer

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Frequently Asked Questions

When should I plant Potatoes in Lake County, IL?

Lake County is in Zone 5b with an average last frost of April 21. Plan your Potatoes 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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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.