When to Plant Nasturtiums in Wisconsin
Edible flowers that double as pest traps. Plant near vegetables to lure aphids away from your food crops.
The Short Answer
Wisconsin Frost Dates
Your planting dates depend on which part of Wisconsin you're in. Here are the frost date ranges by region:
| Region | Zones | Last Frost (Spring) | First Frost (Fall) |
|---|---|---|---|
| Northern Wisconsin | 3b, 4a | May 15 - Jun 1 | Sep 10 - Sep 25 |
| Central Wisconsin | 4a, 4b | May 5 - May 20 | Sep 20 - Oct 5 |
| Southern Wisconsin | 4b, 5a, 5b | Apr 25 - May 10 | Oct 1 - Oct 15 |
Nasturtiums Planting Schedule for Wisconsin
Northern Wisconsin (Zones 3b, 4a)
Average last frost: May 15 - Jun 1 · Average first frost: Sep 10 - Sep 25
Central Wisconsin (Zones 4a, 4b)
Average last frost: May 5 - May 20 · Average first frost: Sep 20 - Oct 5
Southern Wisconsin (Zones 4b, 5a, 5b)
Average last frost: Apr 25 - May 10 · Average first frost: Oct 1 - Oct 15
Growing Nasturtiums in Wisconsin
Nasturtiums in Wisconsin's Climate
Nasturtiums add edible beauty to cold-climate gardens from June through frost. Direct sow after last frost — they grow fast in summer warmth. Plant near vegetables as companion and trap plants for aphids. The flowers and leaves have a peppery, watercress-like flavor that brightens salads.
Soil Considerations for Wisconsin
Rich agricultural soils in southern half. Sandy soils in central plain. Heavy clay in some lake regions. Generally fertile. Make sure soil has warmed to at least 55°F before planting nasturtiums outside.
Wisconsin Climate & Growing Season
Cold winters. Warm summers. Lake Michigan moderates eastern climate. Good growing season in south. Short season in north. 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 Wisconsin: Northern Wisconsin (3b, 4a) has a last frost around May 15 - Jun 1, while Southern Wisconsin (4b, 5a, 5b) sees frost end around Apr 25 - May 10. 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