PlantingWindowThe American Planting Almanac

When to plant mustard greens in Cheyenne, Wyoming

April 16 – April 30

Direct-sow outdoors · typical Cheyenne year

Climate basis: NOAA station Cheyenne Wfo, WY (USC00481676), 7 mi (12 km) from downtown Cheyenne (ZCTA 82001 centroid), elevation 6119 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 (May 14). One year in ten still freezes after May 28.

Last spring freezeMay 141-in-10 after May 28
First fall freezeOctober 11-in-10 before Sep 17
Frost-free season≈ 139 daysmedian at 32°F
Hard freeze, 28°May 3 – Oct 10kills even hardy greens
USDA zone5b-15 to -10°F winter low — not frost timing

The Cheyenne year

Direct-sow outdoorsApr 16 – Apr 30
Fall plantingAug 6 – Sep 3
  • indoors under lights
  • in the garden
  • frost-free season
  • 1-in-10 years still freeze to May 28
Mustard greens in Cheyenne · freeze context from Cheyenne Wfo, WY, 1991–2020 normals.

Every method, with its sources

Direct-sow outdoors

Apr 16 – Apr 30

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 (May 14). Purdue University Extension

Fall planting

Aug 6 – Sep 3

Purdue Table 2: plant fall mustard greens at least 4–8 weeks before the first fall frost. Anchored to the median first fall freeze (Oct 1). 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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