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USDA hardiness zone

Zone 5a

Rolled up from the 2,454 ZIP codes in our data that are classified zone 5a, covering 1,098 nurseries and garden centers across 325 cities we track in this zone.

Average minimum winter temperature

-20°F

Last spring frost range

Apr 13–Jun 24

First fall frost range

Aug 28–Oct 28

Average frost-free growing season

150 days

Average monthly temperature

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
18.5° 21.8° 32.6° 44.5° 56.2° 65.9° 70.6° 68.6° 60.7° 47.9° 34.9° 23.7°

NOAA 1991–2020 Climate Normals, averaged across this zone's member ZIPs.

Crops by frost hardiness

What grows here, and when

This zone's own last-frost dates range across Apr 13–Jun 24. Hardy and semi-hardy crops can go in before that date; tender and very-tender crops need to wait until after it. See each crop's own guide for exact windows at a specific location in this zone.

Planting windows and crop timing here are computed from USDA/NOAA climate data and the university extension sources cited below, not a site visit or soil test. Treat this as a starting point: local conditions vary, and a local nursery or extension office can advise on your exact site. See our full Disclaimer.

Find your exact zone by ZIP →

Zone 5a means an average annual extreme minimum winter temperature of -20°F to -15°F on the 2023 USDA Plant Hardiness Zone Map (USDA/ARS with the PRISM Climate Group at Oregon State University, 1991-2020 records). Every ZIP in this rollup carries its zone matched by centroid against the map, not by its polygon boundary, through phzmapi.org's ZIP-level derivation, since USDA publishes no official ZIP crosswalk of its own.

Both frost ranges above run close to ten weeks wide across this zone's own ZIPs, so treat the median as the number to check your own ZIP against, not the date to plant by.

We track nurseries across 13 states in zone 5a, from Alaska to Virginia, with the most around Minneapolis, followed by Sioux Falls, SD and Anchorage, AK. A single zone label covering both an upper-Midwest city and a subarctic one is exactly why USDA's own zone definition is about winter cold alone, not climate generally.

Cities we track in zone 5a

Nearby zones

All zones

USDA 2023 Plant Hardiness Zone Map (zone boundaries, via the phzmapi.org ZIP-level derivation) and NOAA 1991–2020 Climate Normals (frost dates, growing season, monthly temperatures).