PlantingWindowThe American Planting Almanac

When to plant mustard greens in St. Louis, Missouri

March 4 – March 18

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 mustard greens 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 4 – Mar 18
Fall plantingSep 9 – Oct 7
  • indoors under lights
  • in the garden
  • frost-free season
  • 1-in-10 years still freeze to Apr 18
Mustard greens in St. Louis · freeze context from St Louis Sci Ctr, MO, 1991–2020 normals.

Every method, with its sources

Direct-sow outdoors

Mar 4 – Mar 18

Purdue lists mustard under both hardy (4–6 weeks before the last frost) and semi-hardy (2–4 weeks before); the later semi-hardy start is used. Anchored to the median last spring freeze (Apr 1). Purdue University Extension

Fall planting

Sep 9 – Oct 7

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

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 (1)

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