Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for Chicago, IL

Chicago, IL is in USDA zones 6a to 6b across its 80 ZIP codes. The median last spring frost is April 10 and the first fall frost November 5.

Chicago on the zone map

Outlined: its 53 ZIP code areas · tap the map for the zone at any spot · scroll or pinch to zoom

Not the official USDA Plant Hardiness Zone Map. Zones come from the 2023 USDA hardiness-zone data by the PRISM Group, Oregon State University; we re-mapped and recolored them. The official map is at planthardiness.ars.usda.gov.

Zones6a–6b−10 to 0 °F

ZIP codes80

Last frostApr 10

First frostNov 5

Growing season208 days

6a 42 ZIPs 6b 38 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

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Forecast data: National Weather Service (api.weather.gov), public domain. This is not a warning service — for official frost and freeze warnings see weather.gov.

Frost dates in Chicago, IL

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostApril 10median — 50% chance of a later frost

Safe for tender plantsApril 25only 10% chance of frost after

First fall frostNovember 5median — 10% chance by Oct 24

Growing season208 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 1 and returns around November 15.

From the NOAA station Chicago Northerly Is, IL, elevation 584 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.

When to plant vegetables in Chicago

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Feb 27 – Mar 13

SpinachSow outdoors · Feb 27 – Mar 20

Broccoli, cabbageStart indoors · Jan 30 – Feb 13

Broccoli, cabbageTransplant · Mar 20 – Apr 3

Onion setsPlant outdoors · Mar 13 – Mar 27

PotatoesPlant outdoors · Mar 20 – Apr 3

LettuceSow outdoors · Mar 13 – Mar 27

Carrots, beetsSow outdoors · Mar 20 – Apr 3

TomatoesStart indoors · Feb 13 – Feb 27

TomatoesTransplant · Apr 17 – May 1

Peppers, eggplantStart indoors · Jan 30 – Feb 13

Peppers, eggplantTransplant · Apr 24 – May 8

BeansSow outdoors · Apr 17 – May 1

Sweet cornSow outdoors · Apr 17 – May 1

Cucumbers, squashSow outdoors · Apr 17 – May 1

Fall lettuce, spinachSow outdoors · Sep 10 – Sep 24

GarlicPlant cloves · Oct 22 – Nov 26

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 10) and first fall frost (Nov 5) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.

When spring arrived in 2026

In 2026, spring leaf-out near 60608 came on Mar 21 — 12 days earlier than the 1991–2020 average (Apr 2).

average
Apr 22026
Mar 21

JanFebMarAprMayJun

The Spring Index marks the day when accumulated warmth is enough for lilac and honeysuckle to leaf out — a widely used signal that the growing season has started. Source: USA National Phenology Network, www.usanpn.org — Spring Indices, first leaf, 2026 (data as of 2026-09-08) and 30-year average 1991–2020 (CC BY 4.0).

Native plants for zone 6a in Illinois

610 plants native to the lower 48 states, recorded in Illinois, and rated by the USDA to survive −10 °F or colder — the bottom of zone 6a. Each links to its USDA PLANTS profile.

Source: USDA, NRCS. 2026. The PLANTS Database (plants.usda.gov), National Plant Data Team — state distribution, native status and the “Temperature, Minimum” characteristic. Check light, moisture and soil needs before buying; local nurseries and your state native plant society can confirm what thrives in Chicago, IL.

Soil in Chicago, IL

The soil mapped at the center of ZIP 60608 is Orthents — silty clay, moderately well drained. Much of the area is built over (urban land); this is the natural soil underneath.

TextureSilty clayholds water and nutrients; slow to drain and warm up

pH6.7neutral; most vegetables like 6.0–7.0

DrainageModerately well drainednatural drainage class

Organic matter1.25%low — add compost

Hydrologic groupDwater soaks in very slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Urban land.

Soil Survey Staff, Natural Resources Conservation Service, USDA. Soil Survey Geographic (SSURGO) Database, via Soil Data Access, accessed 2026-10-29. The soil at the center point of ZIP 60608; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Chicago, IL

Summer high81 °Faverage high, July

Winter low20 °Faverage low, January

Hot days13days a year at 90 °F or more

Freezing nights97nights a year at 32 °F or less

Growing degree days3,106base 50 °F — the season’s usable heat

Longest day15 h 13 mindaylight on June 21

Shortest day9 h 08 mindaylight on December 21

Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)

Precipitation44.3 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Chicago Northerly Is, IL (3 mi away); precipitation: Chicago 5.5 Ese, IL (5 mi away). Daylight is calculated from latitude.

ZIP codes in Chicago

Planting zone for Chicago, IL

Chicago on the zone map

Frost forecast — next 7 nights

Frost dates in Chicago, IL

When to plant vegetables in Chicago

When spring arrived in 2026

Native plants for zone 6a in Illinois

Trees 78

Shrubs 108

Wildflowers & perennials 220

Grasses 178

Vines 9

Soil in Chicago, IL

Climate in Chicago, IL

Average high and low, by month

Precipitation by month inches

ZIP codes in Chicago

Questions about Chicago