When to plant cauliflower in Madison, Wisconsin

April 17 – May 1

Transplant 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. Transplant cauliflower outdoors 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

Start seeds indoorsMar 6 – Mar 20

Transplant outdoorsApr 17 – May 1

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

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

Every method, with its sources

Start seeds indoors

Mar 6 – Mar 20

Sow 4–6 weeks before the set-out window opens (UNH 4–6 weeks; Missouri G6570 6–8 weeks). Anchored to the median last spring freeze (May 1). University of New Hampshire Extension · University of Missouri Extension

Transplant outdoors

Apr 17 – May 1

UNH: set out 2 weeks before the last frost; Purdue's semi-hardy class allows 2–4 weeks before. The later UNH point is used, with a 14-day span. Anchored to the median last spring freeze (May 1). University of New Hampshire Extension · Purdue University Extension

Variety assumption: Assumes an average variety (about 55–75 days from transplant).

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 (3)

University of New Hampshire Extension: Growing Vegetables: When to Plant Your Vegetable Garden [fact sheet] (accessed 2026-07-24)
Per-crop 'time from seed to transplant' and 'safe to set out in garden' relative to last frost.
University of Missouri Extension: Starting Plants Indoors from Seeds (G6570) (accessed 2026-07-24)
Weeks needed to grow vegetable transplants indoors (Table 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.

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