What Growing Zone Is Illinois In?
USDA hardiness zones
5a to 7a
2023 USDA Plant Hardiness Zone Map
Illinois spans USDA hardiness zone 5a to 7a across its major population centers, according to the 2023 USDA Plant Hardiness Zone Map. That's a real range, not a single number: where you fall in it depends on where in the state you actually are.
Hardiness zone for ZIP 60602 (Chicago)
Your USDA hardiness zone
Zone 6b
Avg. annual minimum (°F)
-5°F to 0°F
Avg. annual minimum (°C)
-21°C to -18°C
Nearest reference point: Chicago, IL
This is a regional estimate based on the nearest of 826 reference points, each matched to the official 2023 USDA zone map. It’s accurate to within about a half-zone across most of the country, but elevation shifts zones over short distances, so if you’re in mountainous terrain, check the official USDA map for your exact address (see Sources below).
Illinois's USDA Hardiness Zones
Here's how the zone shifts across Illinois's major cities:
For your exact zone by ZIP code, use the Hardiness Zone Finder, and for what a zone number actually measures (and doesn't), see how zones actually work.
Frost Dates in Illinois
Frost dates track zone, so they shift across Illinois the same way the zone number does:
- Northwest hills (Galena) (zone 5): average last frost Apr 8 - Apr 22, average first frost Oct 8 - Oct 22.
- Southern Illinois (zone 7): average last frost Mar 18 - Apr 1, average first frost Oct 29 - Nov 12.
These are averages, not guarantees. For your specific frost window, use the Frost Date Calculator. For a full vegetable-by-vegetable planting calendar already calculated from Illinois's frost dates, see the Illinois Planting Calendar.
The Illinois State Climatologist Office documents a real north-south growing-season gradient: the 1991-2020 average growing season runs about 215 days in far southern Illinois versus about 180 days in far northern Illinois.
What Grows Well in Illinois's Zones
A few real, zone-appropriate picks recommended by University of Illinois Extension for Illinois landscapes: not an exhaustive list, but a genuine starting point.
- Kentucky coffeetree (Gymnocladus dioica)
- Eastern redbud (Cercis canadensis)
- Downy serviceberry (Amelanchier arborea)
- Eastern white pine (Pinus strobus)
- American elm, 'New Harmony' (Dutch elm disease-resistant) (Ulmus americana 'New Harmony')
Ready to find your exact zone? Use the Hardiness Zone Finder: enter your ZIP code for a precise match against the 2023 USDA map.
Illinois Growing Zone FAQ
What growing zone is Illinois in?
Illinois spans USDA hardiness zones 5a to 7a on the 2023 USDA Plant Hardiness Zone Map. Rockford is zone 5b and Chicago is zone 6b; enter your ZIP code in the Hardiness Zone Finder for your exact zone.
What growing zone is Chicago, IL?
Chicago is in USDA hardiness zone 6b on the 2023 USDA map. Zones within a city can differ by half a zone, so check your ZIP code for an exact match.
What growing zone is Rockford, IL?
Rockford is in USDA hardiness zone 5b on the 2023 USDA map. Zones within a city can differ by half a zone, so check your ZIP code for an exact match.
What growing zone is Springfield, IL?
Springfield is in USDA hardiness zone 6a on the 2023 USDA map. Zones within a city can differ by half a zone, so check your ZIP code for an exact match.
What growing zone is Peoria, IL?
Peoria is in USDA hardiness zone 6a on the 2023 USDA map. Zones within a city can differ by half a zone, so check your ZIP code for an exact match.
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The Spacing & Planting Cheat Sheet
When to start, when to plant, how far apart.
Sources & further reading
Zone and city data checked against the official USDA Plant Hardiness Zone Map. Plant recommendations sourced from University of Illinois Extension. Climate note sourced from Illinois State Climatologist Office. For more on how we build and verify reference data across this site, see our methodology page.
Growing zones in nearby states
Gardening near a state line? Zones don't stop at the border:
- Indiana growing zones
- Missouri growing zones
- Wisconsin growing zones
- Kentucky growing zones
- Iowa growing zones
Or browse all 51 state growing-zone guides.