When to Plant Corn (Sweet) in Illinois
Nothing says summer like fresh sweet corn. Plant in blocks (not rows) for proper pollination.
The Short Answer
Illinois Frost Dates
Your planting dates depend on which part of Illinois you're in. Here are the frost date ranges by region:
| Region | Zones | Last Frost (Spring) | First Frost (Fall) |
|---|---|---|---|
| Northern Illinois (Chicago) | 5a, 5b | Apr 25 - May 10 | Oct 1 - Oct 15 |
| Central Illinois | 5b, 6a | Apr 15 - May 1 | Oct 5 - Oct 20 |
| Southern Illinois | 6b, 7a | Apr 1 - Apr 15 | Oct 15 - Nov 1 |
Corn (Sweet) Planting Schedule for Illinois
Northern Illinois (Chicago) (Zones 5a, 5b)
Average last frost: Apr 25 - May 10 · Average first frost: Oct 1 - Oct 15
Central Illinois (Zones 5b, 6a)
Average last frost: Apr 15 - May 1 · Average first frost: Oct 5 - Oct 20
Southern Illinois (Zones 6b, 7a)
Average last frost: Apr 1 - Apr 15 · Average first frost: Oct 15 - Nov 1
Growing Corn (Sweet) in Illinois
Corn (Sweet) in Illinois's Climate
Your climate is classic corn country. Direct sow from mid-May. Succession plant through late June for harvests from July through September. Moderate summer temperatures produce long-lasting ears without the heat stress that shortens quality in southern states. European corn borer and corn earworm are the primary pests.
Soil Considerations for Illinois
Rich prairie soils — some of the most fertile in the country. Heavy clay in many areas. Well-suited for most vegetables. Make sure soil has warmed to at least 60°F before planting corn (sweet) outside.
Illinois Climate & Growing Season
Continental climate with four seasons. Hot, humid summers. Cold winters. Good growing season length in central and southern regions. Corn (Sweet) cannot tolerate any frost, so wait until all frost danger has passed before transplanting outside. Watch local forecasts carefully in spring.
Growing season length varies across Illinois: Northern Illinois (Chicago) (5a, 5b) has a last frost around Apr 25 - May 10, while Southern Illinois (6b, 7a) sees frost end around Apr 1 - Apr 15. This difference matters for corn (sweet) — transplant timing shifts by several weeks across the state.
Growing Tips
Plant in blocks of at least 4x4 for wind pollination. Corn is a heavy feeder — amend soil with compost before planting.
Companion Planting
Plant corn (sweet) alongside these companions for better growth:
Keep corn (sweet) away from:
The Bottom Line
Last reviewed: March 29, 2026