When to Plant Nasturtiums in Illinois
Edible flowers that double as pest traps. Plant near vegetables to lure aphids away from your food crops.
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 |
Nasturtiums 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 Nasturtiums in Illinois
Nasturtiums in Illinois's Climate
Nasturtiums thrive from spring through frost in your climate. They prefer poor soil — don't fertilize or you'll get leaves without flowers. The trailing types spill beautifully from containers. Plant near tomatoes and squash to draw aphids away from your vegetable crops.
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 55°F before planting nasturtiums outside.
Illinois Climate & Growing Season
Continental climate with four seasons. Hot, humid summers. Cold winters. Good growing season length in central and southern regions. Nasturtiums 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 nasturtiums — transplant timing shifts by several weeks across the state.
Growing Tips
Both flowers and young leaves are edible with a peppery taste. Thrives in poor soil — too much nitrogen means all leaves, no flowers.
Companion Planting
Plant nasturtiums alongside these companions for better growth:
The Bottom Line
Last reviewed: March 29, 2026