When to plant potatoes in Madison, Wisconsin

March 20 – April 3

Direct-sow outdoors · typical Madison year

Climate basis: NOAA station Uw Arboretum - Madison, WI (USC00470273), 4 mi (6 km) from downtown Madison (ZCTA 53703 centroid), elevation 870 ft, on the 1991–2020 climate normals. Plant seed potatoes from approximately the dates above, anchored to the median last spring 32°F freeze (May 1). One year in ten still freezes after May 17.

Last spring freezeMay 11-in-10 after May 17

First fall freezeOctober 91-in-10 before Sep 26

Frost-free season≈ 161 daysmedian at 32°F

Hard freeze, 28°Apr 20 – Oct 20kills even hardy greens

USDA zone5b-15 to -10°F winter low — not frost timing

The Madison year

Direct-sow outdoorsMar 20 – Apr 3

indoors under lights
in the garden
frost-free season
1-in-10 years still freeze to May 17

Potatoes in Madison · freeze context from Uw Arboretum - Madison, WI, 1991–2020 normals.

Every method, with its sources

Direct-sow outdoors

Mar 20 – Apr 3

Purdue: hardy — plant seed pieces 4–6 weeks before the last spring frost. Minnesota adds the practical caveat: plant as soon as the soil warms. Anchored to the median last spring freeze (May 1). Purdue University Extension · University of Minnesota Extension

Start seeds indoors

Not calculated

Potatoes are grown from seed pieces, not indoor-started seedlings.

Transplant outdoors

Not calculated

The cited extension guides do not time an outdoor transplanting window for this crop.

Fall planting

Not calculated

No source-backed fall planting rule exists for this crop in the registry, so no fall window is calculated.

Variety assumption: Assumes a mid-season variety (about 90–110 days from planting).

These windows describe typical years (1991–2020 climate normals), not this year's forecast. Freezes happen outside them — especially in frost pockets, valleys, and urban edges. Watch the forecast before committing tender plants.

This week, not a typical year:

Crop rule sources (2)

Purdue University Extension: Indiana Vegetable Planting Calendar (HO-186-W) (accessed 2026-07-24)
Hardiness classes: hardy = plant 4-6 wk before last spring frost; semi-hardy = 2-4 wk before; tender = after average last frost; very tender = at least 2 wk after. Table 2: fall planting at least 4-8 wk before first fall frost.
University of Minnesota Extension: Growing potatoes (accessed 2026-07-24)
"Plant seed pieces as soon as the soil warms" — soil-temperature caveat to the frost-relative rule.

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