Blog

When to Plant Corn in McDonough County, IL

Corn is a warm-season grass grown for its sweet ears, which are best eaten soon after harvest. It is wind-pollinated and must be planted in blocks for good kernel fill.

McDonough County, Illinois is in USDA Zone 5b. The average last spring frost is April 17 and the first fall frost is October 17, giving you a growing season of approximately 183 days.

At an elevation of 738 feet, McDonough County receives approximately 37.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84ยฐF, so choose short-season varieties of Corn to ensure they mature before fall.

McDonough County, IL (Zone 5b) Moderate season
183 days
Last Spring Frost April 17
183 growing days
First Fall Frost October 17

McDonough County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (64 days to spare)
Transplant: Apr 11 🍅 Harvest: Jun 13 – Aug 8
Recommended (50%) ✓ Fits season (64 days to spare)
Transplant: Apr 17 🍅 Harvest: Jun 19 – Aug 14
Safe Start (90%) ✓ Fits season (65 days to spare)
Transplant: Apr 30 🍅 Harvest: Jul 2 – Aug 27

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
0.9″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 723 gal / 100 sq ft
Corn needs ~1,040 GDD — county provides 2,379 GDD Excellent fit

Corn Planting Timeline โ€” McDonough County, IL

Corn Planting Calendar

Activity When Date Range
Direct Sow April 24 Apr 24 โ€“ May 15
Harvest June 26 Jun 26 โ€“ Aug 21

Plant 1" deep ยท 12" apart ยท Rows 36" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April Direct Sow
May 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

60โ€“100 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 5b

Growing Season

183 days

Growing Tips for McDonough County

Plant in blocks of at least 4 rows rather than single rows for proper pollination. Direct sow after soil reaches 60F. Side-dress with nitrogen when plants are knee-high.

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes
  • Celery

Level Up Your Garden

Frequently Asked Questions

When should I plant Corn in McDonough County, IL?

McDonough County is in Zone 5b with an average last frost of April 17. Plan your Corn planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is McDonough County, IL?

McDonough County, Illinois is in USDA Hardiness Zone 5b. The average last spring frost is April 17 and first fall frost is October 17.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help McDonough County gardeners in Zone 5b 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 McDonough County, IL. Local conditions may vary. Last updated: April 2026.