2026 Planting Guide
Spring cropWhen to Plant Corn (Maize) in Illinois
Complete guide to growing corn (maize) in Illinois with optimal planting dates, recommended varieties, soil requirements, pest management, and harvest timing. Data sourced from USDA and state extension services.
Monthly Planting Calendar
Visual overview of the corn (maize) growing season in Illinois. Red diamond markers indicate frost date boundaries.
Quick Facts
Min. Soil Temp
50°F (10°C) minimum
Growing Period
100-120 days
From planting to harvest
Last Spring Frost
April 20
Wait until after this date
First Fall Frost
October 12
Harvest before this date
Monthly Task Timeline
Month-by-month guide for managing corn (maize) in Illinois.
January - March
Off-seasonCover crop planting, soil testing, equipment maintenance, and planning for next season.
April - May
PlantPrepare soil, apply starter fertilizer, and sow seeds at recommended depth and spacing.
June - August
Grow & MonitorIrrigate as needed, scout for pests, apply side-dress fertilizer, and manage weeds.
September - November
HarvestCheck maturity indicators, schedule equipment, harvest at optimal moisture content.
December
Off-seasonCover crop planting, soil testing, equipment maintenance, and planning for next season.
Best Corn (Maize) Varieties for Illinois
These varieties have proven performance in Illinois's climate and soil conditions. Always source certified seed from reputable dealers.
| # | Variety | Best For |
|---|---|---|
| 1 | Pioneer P1366AML | Illinois climate |
| 2 | DeKalb DKC62-89 | Illinois climate |
| 3 | Asgrow | Illinois climate |
| 4 | LG Seeds LG62C35VT2P | Illinois climate |
Growing Tips for Illinois
Region-specific advice from agricultural extension services and experienced Illinois farmers.
Southern IL can plant 1-2 weeks earlier than northern counties
Use Bt hybrids in areas with history of corn borer pressure
Rotate with soybeans to break pest cycles
Monitor for tar spot disease in humid conditions
Pest & Disease Watch
Monitor for these threats throughout the growing season. Integrated Pest Management (IPM) is recommended.
Corn borers
Scout regularly and use integrated pest management
Corn rootworm
Scout regularly and use integrated pest management
Fall armyworm
Scout regularly and use integrated pest management
Aphids
Scout regularly and use integrated pest management
Cutworms
Scout regularly and use integrated pest management
Companion Planting
These plants grow well alongside corn (maize), improving pest control, pollination, and nutrient availability.
Frost Dates
Last Spring Frost
April 20
Wait until after this date before planting frost-sensitive crops outdoors.
First Fall Frost
October 12
Plan to complete harvest of warm-season crops before this date arrives.
Frequently Asked Questions
When is the best time to plant corn (maize) in Illinois?
The optimal planting window for corn (maize) in Illinois is April 15 to May 15. Soil temperature should reach at least 50°F (10°C) minimum before planting. The total growing period is 100-120 days.
What varieties of corn (maize) grow best in Illinois?
The best varieties for Illinois include Pioneer P1366AML, DeKalb DKC62-89, Asgrow, LG Seeds LG62C35VT2P. These varieties are adapted to local climate and soil conditions and have proven performance records.
When can I harvest corn (maize) in Illinois?
The harvest window for corn (maize) in Illinois is typically September 20 to November 1. The crop takes 100-120 days from planting to reach maturity.
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Data Sources
Data sourced from USDA NASS Crop Planting Dates, Illinois Cooperative Extension Service, and NOAA frost date records. Last updated: March 2026.
Planting dates are averages and may vary by county, elevation, and local microclimate. Always consult your local extension office for the most precise recommendations.