PlantingWindowThe American Planting Almanac

When to plant kale in St. Louis, Missouri

March 11 – March 25

Direct-sow outdoors · typical St. Louis year

Climate basis: NOAA station St Louis Sci Ctr, MO (USC00237452), 4 mi (7 km) from downtown St. Louis (ZCTA 63101 centroid), elevation 515 ft, on the 1991–2020 climate normals. Direct-sow kale from approximately the dates above, anchored to the median last spring 32°F freeze (April 1). One year in ten still freezes after April 18.

Last spring freezeApril 11-in-10 after Apr 18
First fall freezeNovember 41-in-10 before Oct 24
Frost-free season≈ 218 daysmedian at 32°F
Hard freeze, 28°Mar 22 – Nov 15kills even hardy greens
USDA zone7a0 to 5°F winter low — not frost timing

The St. Louis year

Direct-sow outdoorsMar 11 – Mar 25
Fall plantingSep 9 – Oct 7
  • indoors under lights
  • in the garden
  • frost-free season
  • 1-in-10 years still freeze to Apr 18
Kale in St. Louis · freeze context from St Louis Sci Ctr, MO, 1991–2020 normals.

Every method, with its sources

Direct-sow outdoors

Mar 11 – Mar 25

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 (Apr 1). Penn State Extension (York County Master Gardeners) · Purdue University Extension

Fall planting

Sep 9 – Oct 7

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