When to Plant Marigolds in Wisconsin
The ultimate companion plant. Marigolds repel pests, attract pollinators, and add cheerful color all season long.
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 |
Marigolds 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 Marigolds in Wisconsin
Marigolds in Wisconsin's Climate
Marigolds are surprisingly effective in cold climates despite their frost sensitivity. Start indoors or buy transplants — they grow fast once summer warmth arrives. Plant among vegetables for pest deterrence. French marigolds suppress root-knot nematodes through root chemicals, though nematodes are less common in cold soils.
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 60°F before planting marigolds outside.
Wisconsin Climate & Growing Season
Cold winters. Warm summers. Lake Michigan moderates eastern climate. Good growing season in south. Short season in north. Marigolds 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 marigolds — transplant timing shifts by several weeks across the state.
Growing Tips
French marigolds are best for pest control in vegetable gardens. Deadhead spent flowers to keep them blooming until frost.
Companion Planting
Plant marigolds alongside these companions for better growth:
The Bottom Line
Last reviewed: March 29, 2026