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When to Plant Potatoes in Whiteside 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.

Whiteside County, Illinois is in USDA Zone 5a. The average last spring frost is April 16 and the first fall frost is October 16, giving you a growing season of approximately 183 days.

At an elevation of 682 feet, Whiteside County receives approximately 30.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84ยฐF, so choose short-season varieties of Potatoes to ensure they mature before fall.

Whiteside County, IL (Zone 5a) Moderate season
183 days
Last Spring Frost April 16
183 growing days
First Fall Frost October 16

Whiteside 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 (30 days to spare)
Start indoors: Feb 13 Transplant: Apr 24 🍅 Harvest: Jul 3 – Sep 11
Recommended (50%) ✓ Fits season (29 days to spare)
Start indoors: Feb 19 Transplant: Apr 30 🍅 Harvest: Jul 9 – Sep 17
Safe Start (90%) ✓ Fits season (31 days to spare)
Start indoors: Mar 7 Transplant: May 16 🍅 Harvest: Jul 25 – Oct 3

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
0.7″/week
You supply
0.3″/week
Watering frequency 1-2 times/week
Season total 500 gal / 100 sq ft
Potatoes needs ~1,235 GDD — county provides 2,379 GDD Excellent fit

Potatoes Planting Timeline โ€” Whiteside County, IL

Potatoes Planting Calendar

Activity When Date Range
Start Indoors February 19 Feb 19 โ€“ Mar 5
Transplant Outdoors April 30 Apr 30 โ€“ May 14
Direct Sow April 23 Apr 23 โ€“ May 14
Harvest July 9 Jul 9 โ€“ Sep 17

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

Month-by-Month Timeline

MonthActivities
January โ€”
February Start Indoors
March Start Indoors
April Transplant Outdoors 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 5a

Growing Season

183 days

Growing Tips for Whiteside 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

Level Up Your Garden

Frequently Asked Questions

When should I plant Potatoes in Whiteside County, IL?

Whiteside County is in Zone 5a with an average last frost of April 16. Plan your Potatoes planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Whiteside County, IL?

Whiteside County, Illinois is in USDA Hardiness Zone 5a. The average last spring frost is April 16 and first fall frost is October 16.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Whiteside 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 Whiteside County, IL. Local conditions may vary. Last updated: April 2026.