PlantingWindowThe American Planting Almanac

When to plant collards in Boston, Massachusetts

March 21 – April 4

Direct-sow outdoors · typical Boston year

Climate basis: NOAA station Boston Logan INTL AP, MA (USW00014739), 3 mi (5 km) from downtown Boston (ZCTA 02108 centroid), elevation 12 ft, on the 1991–2020 climate normals. Direct-sow collards from approximately the dates above, anchored to the median last spring 32°F freeze (April 4). One year in ten still freezes after April 17.

Last spring freezeApril 41-in-10 after Apr 17
First fall freezeNovember 91-in-10 before Oct 29
Frost-free season≈ 218 daysmedian at 32°F
Hard freeze, 28°Mar 28 – Nov 21kills even hardy greens
USDA zone7a0 to 5°F winter low — not frost timing

The Boston year

Direct-sow outdoorsMar 21 – Apr 4
Fall plantingSep 14 – Oct 12
  • indoors under lights
  • in the garden
  • frost-free season
  • 1-in-10 years still freeze to Apr 17
Collards in Boston · freeze context from Boston Logan INTL AP, MA, 1991–2020 normals.

Every method, with its sources

Direct-sow outdoors

Mar 21 – Apr 4

Purdue: hardy — 4–6 weeks before the last frost; Penn State's earliest sowing Apr 17 (−14 days) is the later start and is used. Anchored to the median last spring freeze (Apr 4). Penn State Extension (York County Master Gardeners) · Purdue University Extension

Fall planting

Sep 14 – Oct 12

Purdue Table 2: plant fall collards at least 4–8 weeks before the first fall frost. Anchored to the median first fall freeze (Nov 9). Purdue University Extension

Variety assumption: Assumes an average variety (about 70–80 days; Penn State lists 80).

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)

Keep exploring

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