The New Almanac

USDA Zone 5b

Zone 5 · The Corn Belt North

Average annual extreme minimum temperature: -15 to -10 °F (-26.1°C to -23.3°C).

Iowa's heartland, southern Minnesota, upstate New York, and the cooler Great Lakes country — −20 to −10°F winters with a season long enough that the question shifts from "can I grow it" to "which variety."

By the numbers

Median last frost
May 1
Median first frost
October 10
Median season
162 days
ZIPs tracked
2,592

Medians across every ZIP we track in zone 5b, derived from NOAA 1991–2020 climate normals. Look up your own ZIP for local dates — within a zone, frost varies by weeks.

Where you'll find zone 5

The bulk of Iowa (94% of its ZIPs in our data are 5a or 5b), southern and central Minnesota's warmer third, much of upstate New York and northern New England's valleys, and the cooler upper Great Lakes shores. Even coastal Alaska touches 5 in its mildest harbors.

Vegetables that earn their keep

  • The full cool-season roster: beets, broccoli, cabbage, spinach, peas, lettuce, radishes (Cornell)
  • The full warm-season roster after the last frost: tomatoes, peppers, beans, sweet corn, eggplant, cucumbers, squash
  • Succession sowings of lettuce and radish through spring and again in late summer (Cornell)

Fruits & perennials that overwinter

  • Disease-resistant apples (Ohio State's home-orchard picks): Pristine, Pixie Crunch, William's Pride, Redfree, Jonafree, Liberty, Enterprise, Goldrush
  • Every zone-3/4 apple, raspberry, tart cherry, juneberry, and honeyberry remains an option
  • Honeyberries to the top of their preferred range (UW–Madison rates them zones 1–8; Saskatchewan-bred varieties suit the Upper Midwest)

Room to be choosy

Zone 5's season — Cornell's planning dates of roughly May 20 to October 1 stretch wider in its warmer half — fits nearly every common vegetable without heroics. The gardening question becomes variety selection: disease resistance, days-to-maturity, and flavor, rather than bare survival.

The orchard opens up

Ohio State's home-orchard list for this climate leans on disease-resistant apples — Liberty, Enterprise, Goldrush, William's Pride — that crop reliably with minimal spraying. Rootstock choice (dwarf, semi-dwarf, standard) now matters more than winter-kill risk. The cold-country fruits from zones 3–4 all still thrive.

Spring frost is the heartbreaker

The danger here isn't winter — it's the late-April bloom meeting a mid-May frost. Ohio State's siting advice for fruit: choose ground "free of spring frosts" with good air circulation, meaning elevation the cold air can drain away from. The same logic protects early vegetable plantings.

Watch the new pests north

Spotted wing drosophila reached northern bramble plantings years ago (NDSU flags it alongside mosaic viruses as the raspberry concerns). Mild-winter zones export their problems northward as winters soften — a reason to favor resistant varieties even where the climate seems forgiving.

Plant guides, timed to your frost dates

Every guide gives its planting calendar relative to your last frost — the dates above (or your ZIP's) drop straight in.

Sources