When to Plant Radishes in Illinois
The fastest vegetable in the garden — some varieties are ready in just 25 days. Perfect for impatient gardeners and kids.
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 |
Radishes 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 Radishes in Illinois
Radishes in Illinois's Climate
Radishes are the instant-gratification crop of spring. Direct sow 4 weeks before last frost and succession plant every 2 weeks through May. They bolt and turn pithy once temperatures exceed 80°F consistently. Resume sowing in September for fall harvest. Great for kids and first-time gardeners.
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. Loose, well-drained soil is especially important for radishes since the edible portion grows underground. If your soil is heavy clay, consider raised beds.
Illinois Climate & Growing Season
Continental climate with four seasons. Hot, humid summers. Cold winters. Good growing season length in central and southern regions. Radishes can handle frost well, which is an advantage in Illinois's climate. You can push planting dates earlier in spring and extend into fall.
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 radishes — but radishes handle frost well, so the timing difference is less critical.
Growing Tips
Don't let them stay in the ground too long — they get pithy and hot. Succession plant every 2 weeks for continuous harvest.
Companion Planting
Plant radishes alongside these companions for better growth:
The Bottom Line
Last reviewed: March 29, 2026