PlantingWindowThe American Planting Almanac

When to plant kale in Madison, Wisconsin

April 10 – April 24

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. Direct-sow kale 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 outdoorsApr 10 – Apr 24
Fall plantingAug 14 – Sep 11
  • indoors under lights
  • in the garden
  • frost-free season
  • 1-in-10 years still freeze to May 17
Kale in Madison · freeze context from Uw Arboretum - Madison, WI, 1991–2020 normals.

Every method, with its sources

Direct-sow outdoors

Apr 10 – Apr 24

Purdue: hardy — 4–6 weeks before the last frost; Penn State's earliest sowing Apr 10 (−21 days) is the later start and is used. Anchored to the median last spring freeze (May 1). Penn State Extension (York County Master Gardeners) · Purdue University Extension

Fall planting

Aug 14 – Sep 11

Purdue Table 2: plant fall kale at least 4–8 weeks before the first fall frost. Anchored to the median first fall freeze (Oct 9). Purdue University Extension

Variety assumption: Assumes an average curly variety (about 50–65 days; Penn State lists 60).

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)

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