Warm-Season Vegetable

When to Plant Tomatoes in Wisconsin

America's favorite garden vegetable (technically a fruit). Nothing beats a sun-warmed tomato straight off the vine.

The Short Answer

In Wisconsin, tomatoes planting dates vary by region. In Northern Wisconsin, your average last frost is around May 15 - Jun 1, while Southern Wisconsin sees its last frost around Apr 25 - May 10. Since tomatoes are frost-sensitive, start seeds indoors 6 weeks before your last frost, then transplant outside 2 weeks after frost danger has passed. Rich agricultural soils in southern half. Sandy soils in central plain. Heavy clay in some lake regions. Generally...

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

Tomatoes Planting Schedule for Wisconsin

Northern Wisconsin (Zones 3b, 4a)

Average last frost: May 15 - Jun 1 · Average first frost: Sep 10 - Sep 25

Start Seeds Indoors
6 wks before frost
Transplant Outside
2 wks after frost
Direct Sow
2 wks after frost

Central Wisconsin (Zones 4a, 4b)

Average last frost: May 5 - May 20 · Average first frost: Sep 20 - Oct 5

Start Seeds Indoors
6 wks before frost
Transplant Outside
2 wks after frost
Direct Sow
2 wks after frost

Southern Wisconsin (Zones 4b, 5a, 5b)

Average last frost: Apr 25 - May 10 · Average first frost: Oct 1 - Oct 15

Start Seeds Indoors
6 wks before frost
Transplant Outside
2 wks after frost
Direct Sow
2 wks after frost

Growing Tomatoes in Wisconsin

Tomatoes in Wisconsin's Climate

In cold climates with 120-160 frost-free days, tomatoes demand an aggressive indoor start 6-8 weeks before your last frost. Choose short-season varieties that mature in 55-65 days — Stupice, Sub Arctic Plenty, and Glacier are bred for regions exactly like yours. Black plastic mulch can raise soil temperature by 10-15°F, and floating row cover over transplants during cool June nights adds critical warmth. Your goal is getting ripe tomatoes before September frost — every warm day counts.

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 tomatoes outside.

Wisconsin Climate & Growing Season

Cold winters. Warm summers. Lake Michigan moderates eastern climate. Good growing season in south. Short season in north. Tomatoes 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 tomatoes — transplant timing shifts by several weeks across the state.

Growing Tips

Pinch off suckers for indeterminate varieties. Stake or cage for best results. Water at the base, not overhead, to prevent blight.

Companion Planting

Plant tomatoes alongside these companions for better growth:

Basil Carrots Peppers Marigolds

Keep tomatoes away from:

Brassicas Fennel Dill

The Bottom Line

Tomatoes can be grown successfully across Wisconsin, but your exact planting dates depend on which region you're in. Northern Wisconsin gardeners should plan around a May 15 - Jun 1 last frost, while those in Southern Wisconsin can typically plant earlier. For exact dates based on your zip code, use our free planting date finder.

Related Guides

Tomatoes Growing Guide National planting guide with all states Wisconsin Planting Calendar All plants for Wisconsin Tomatoes in Alabama Alabama planting dates Tomatoes in Alaska Alaska planting dates Tomatoes in Arizona Arizona planting dates Tomatoes in Arkansas Arkansas planting dates
Note: All dates are based on NOAA 30-year Climate Normals and represent historical averages, not predictions for any specific year. Always check your local weather forecast before planting frost-sensitive crops. Learn about our data sources.

Last reviewed: March 29, 2026

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