PlantingWindowThe American Planting Almanac

When to plant mustard greens in Seattle, Washington

February 13 – February 27

Direct-sow outdoors · typical Seattle year

Climate basis: NOAA station Seattle Boeing Fld, WA (USW00024234), 5 mi (8 km) from downtown Seattle (ZCTA 98104 centroid), elevation 20 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 (March 13). One year in ten still freezes after April 1.

Last spring freezeMarch 131-in-10 after Apr 1
First fall freezeNovember 171-in-10 before Nov 1
Frost-free season≈ 247 daysmedian at 32°F
Hard freeze, 28°Feb 18 – Dec 2kills even hardy greens
USDA zone9a20 to 25°F winter low — not frost timing

The Seattle year

Direct-sow outdoorsFeb 13 – Feb 27
Fall plantingSep 22 – Oct 20
  • indoors under lights
  • in the garden
  • frost-free season
  • 1-in-10 years still freeze to Apr 1
Mustard greens in Seattle · freeze context from Seattle Boeing Fld, WA, 1991–2020 normals.

Every method, with its sources

Direct-sow outdoors

Feb 13 – Feb 27

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 (Mar 13). Purdue University Extension

Fall planting

Sep 22 – Oct 20

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 17). 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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