USDA hardiness zone
Zone 6a
Rolled up from the 5,281 ZIP codes in our data that are classified zone 6a, covering 3,484 nurseries and garden centers across 804 cities we track in this zone.
Average minimum winter temperature
-10°F
Last spring frost range
Jan 30–Jun 22
First fall frost range
Sep 2–Dec 11
Average frost-free growing season
169 days
Average monthly temperature
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 25.5° | 28.2° | 37.3° | 48.3° | 59.1° | 68.2° | 72.5° | 70.8° | 63.6° | 51.8° | 40° | 30.3° |
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 Jan 30–Jun 22. 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.
Hardy (49)
- Apple (bare-root fruit tree)
- Apricot (bare-root fruit tree)
- Asparagus
- Bachelor's Button (Cornflower)
- Bare-root rose
- Blackberry
- Blueberry
- Broccoli
- Brussels Sprouts
- Cabbage
- Calendula
- Catnip/Catmint
- Cherry (sweet/tart, bare-root fruit tree)
- Chives
- Collards
- Currant
- Deciduous shade tree (generic, e.g. maple/oak, bare-root or B&B)
- Elderberry
- Evergreen shrub (B&B/potted, e.g. arborvitae, boxwood)
- Flowering deciduous shrub (generic, e.g. lilac/forsythia)
- Garden Peas
- Garlic
- Gooseberry
- Kale
- Kohlrabi
- Larkspur
- Lavender
- Lettuce
- Mint
- Onion (bulb)
- Oregano
- Peach (bare-root fruit tree)
- Pear (bare-root fruit tree)
- Plum (bare-root fruit tree)
- Radish
- Raspberry
- Rhubarb
- Rutabaga
- Sage
- Snapdragon
- Snow Peas
- Spinach
- Strawberry
- Sweet Alyssum
- Sweet Pea
- Table/Bunch Grape
- Tarragon
- Thyme
- Turnip
Semi-hardy (16)
Tender (20)
Zone 6a means an average annual extreme minimum winter temperature of -10°F to -5°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.
Both frost ranges above run far wider here than in the colder zones above: 6a stretches from inland mountain valleys to milder coastal edges, and an unusually early last-frost reading at one of this zone's own ZIPs is a real microclimate, not a typo. That width is the whole reason to check your own ZIP rather than plant on this page's median.
We track nurseries across 21 states in zone 6a, from Arizona to New Hampshire, with Chicago, IL carrying the most, followed by Milwaukee, WI and Penn Yan, NY.
Cities we track in zone 6a
- Chicago, IL (74)
- Milwaukee, WI (59)
- Penn Yan, NY (57)
- Denver, CO (53)
- Colorado Springs, CO (53)
- Fort Wayne, IN (52)
- Omaha, NE (41)
- Syracuse, NY (36)
- Lincoln, NE (35)
- Grand Rapids, MI (34)
- Indianapolis, IN (34)
- Schenectady, NY (30)
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).