PlantingWindowThe American Planting Almanac

When to plant collards in Portland, Maine

April 12 – April 26

Direct-sow outdoors · typical Portland year

Climate basis: NOAA station Portland INTL Jetport, ME (USW00014764), 2 mi (4 km) from downtown Portland (ZCTA 04101 centroid), elevation 45 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 26). One year in ten still freezes after May 7.

Last spring freezeApril 261-in-10 after May 7
First fall freezeOctober 151-in-10 before Oct 2
Frost-free season≈ 170 daysmedian at 32°F
Hard freeze, 28°Apr 14 – Oct 27kills even hardy greens
USDA zone6a-10 to -5°F winter low — not frost timing

The Portland year

Direct-sow outdoorsApr 12 – Apr 26
Fall plantingAug 20 – Sep 17
  • indoors under lights
  • in the garden
  • frost-free season
  • 1-in-10 years still freeze to May 7
Collards in Portland · freeze context from Portland INTL Jetport, ME, 1991–2020 normals.

Every method, with its sources

Direct-sow outdoors

Apr 12 – Apr 26

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

Fall planting

Aug 20 – Sep 17

Purdue Table 2: plant fall collards at least 4–8 weeks before the first fall frost. Anchored to the median first fall freeze (Oct 15). 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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