US Grow Zones

USDA hardiness zone 6a

In zone 6a, the average annual extreme minimum temperature is -10 to -5°F (-23.3 to -20.6°C), based on 1991–2020 data from the 2023 USDA Plant Hardiness Zone Map.

Temperature range-10 to -5°F-23.3 to -20.6°C
ZIP codes5,187in this half-zone
Major cities44on this site
Typical last frostMay 430% risk

What zone 6a means for your garden

A plant labeled "hardy to zone 6a" should survive a typical winter low of -10°F. Most perennials sold at garden centers are rated for this zone or colder; marginal plants rated one zone warmer can survive in sheltered spots. Zone 6b is the warmer half of zone 6.

ZIP codes in zone 6a: 5,183 in contiguous U.S., 4 in Alaska.

Frost dates in zone 6a

Across 44 major cities in zone 6a, the 30%-risk last spring frost ranges from Apr 17 to Jun 10 (median May 4), and the first fall frost has a median of Oct 9. Frost timing depends on elevation, latitude and distance from water — a zone does not set a frost date, so check your city page for local dates.

Typical planting calendar for zone 6a

Based on the median frost dates above. For your exact dates, use your city page.

CropStart indoorsTransplant / plant outDirect sowFall crop sow/plant
TomatoMar 9 – Mar 23May 11 – May 25——
PepperFeb 23 – Mar 9May 18 – Jun 1——
LettuceMar 23 – Apr 6Apr 20 – May 11Apr 6 – May 18Jul 31 – Aug 28
Green Beans——May 11 – Jun 15Jul 17 – Jul 31
Sweet Corn——May 11 – Jun 8—
Zucchini & Summer SquashApr 6 – Apr 13May 11 – May 25May 11 – Jun 1Jul 17 – Jul 31
CucumberApr 6 – Apr 13May 18 – May 25May 11 – Jun 1Jul 17 – Jul 31
Carrot——Apr 13 – May 18Jul 17 – Jul 31
OnionFeb 9 – Feb 23Apr 6 – Apr 20——
Potato—Apr 6 – Apr 27——
BasilMar 23 – Apr 6May 18 – Jun 1May 18 – Jun 8—
Spinach——Mar 23 – Apr 20Aug 14 – Sep 11
KaleMar 9 – Mar 23Apr 6 – Apr 27Apr 6 – Apr 27Jul 31 – Aug 28
BroccoliMar 9 – Mar 23Apr 20 – May 11—Jul 17 – Jul 31
Peas——Mar 23 – Apr 13Jul 31 – Aug 14
EggplantFeb 23 – Mar 9May 18 – Jun 1——
CabbageMar 9 – Mar 23Apr 6 – Apr 20—Jul 17 – Jul 31
Radish——Mar 30 – May 18Aug 28 – Sep 25
Strawberry—Apr 6 – Apr 27——
Beets——Apr 13 – May 25Jul 31 – Aug 14

Cities in zone 6a (44)

Major cities whose center falls in zone 6a:

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