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

Planting zone for Joliet, IL

Joliet, IL is in USDA zones 5b to 6a across its 6 ZIP codes. The median last spring frost is April 19 and the first fall frost October 25.

Joliet on the zone map

Outlined: its 5 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.

Zones5b–6a−15 to −5 °F
ZIP codes6
Last frostApr 19
First frostOct 25
Growing season188 days

5b 1 ZIP   6a 5 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Joliet, IL…

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 Joliet, IL

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 19median — 50% chance of a later frost
Safe for tender plantsMay 7only 10% chance of frost after
First fall frostOctober 25median — 10% chance by Oct 12
Growing season188 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 5 and returns around November 4.

From the NOAA station Joliet Brandon Rd Dam, IL, elevation 545 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 Joliet

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 8 – Mar 22
SpinachSow outdoors · Mar 8 – Mar 29
Broccoli, cabbageStart indoors · Feb 8 – Feb 22
Broccoli, cabbageTransplant · Mar 29 – Apr 12
Onion setsPlant outdoors · Mar 22 – Apr 5
PotatoesPlant outdoors · Mar 29 – Apr 12
LettuceSow outdoors · Mar 22 – Apr 5
Carrots, beetsSow outdoors · Mar 29 – Apr 12
TomatoesStart indoors · Feb 22 – Mar 8
TomatoesTransplant · Apr 26 – May 10
Peppers, eggplantStart indoors · Feb 8 – Feb 22
Peppers, eggplantTransplant · May 3 – May 17
BeansSow outdoors · Apr 26 – May 10
Sweet cornSow outdoors · Apr 26 – May 10
Cucumbers, squashSow outdoors · Apr 26 – May 10
Fall lettuce, spinachSow outdoors · Aug 30 – Sep 13
GarlicPlant cloves · Oct 11 – Nov 15
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 19) and first fall frost (Oct 25) 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 60434 came on Mar 19 — 16 days earlier than the 1991–2020 average (Apr 4).

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 5b in Illinois

584 plants native to the lower 48 states, recorded in Illinois, and rated by the USDA to survive −15 °F or colder — the bottom of zone 5b. Each links to its USDA PLANTS profile.

Trees 77

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican beech80 ft · blooms mid spring · low shade tolerance · to −44 °FAmerican chestnut115 ft · blooms early summer · high shade tolerance · to −33 °FAmerican elm120 ft · blooms early spring · medium shade tolerance · to −46 °FAmerican sycamore100 ft · blooms spring · medium shade tolerance · to −34 °Farborvitae50 ft · blooms mid spring · medium shade tolerance · to −33 °F

Shrubs 102

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °FAllegheny serviceberry35 ft · blooms early spring · low shade tolerance · to −38 °Falternateleaf dogwood25 ft · blooms mid spring · low shade tolerance · to −47 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican hazelnut10 ft · blooms spring · medium shade tolerance · to −33 °FAmerican holly40 ft · blooms mid spring · low shade tolerance · to −20 °F

Wildflowers & perennials 210

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °FAmerican bur-reed3 ft · blooms indeterminate · medium shade tolerance · to −33 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °FAmerican licorice4 ft · blooms late spring · medium shade tolerance · to −38 °FAmerican lotus3 ft · blooms mid summer · high shade tolerance · to −36 °FAmerican pokeweed7 ft · blooms mid summer · low shade tolerance · to −33 °F

Grasses 173

American beachgrass2.5 ft · blooms spring · high shade tolerance · to −28 °Farctic brome3 ft · blooms early summer · low shade tolerance · to −33 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °FBailey's sedge2.1 ft · blooms late spring · low shade tolerance · to −33 °Fbeaked sedge4 ft · blooms late spring · low shade tolerance · to −38 °Fbeaked spikerush3 ft · blooms late spring · high shade tolerance · to −28 °F

Vines 7

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Ffrost grape83 ft · blooms late spring · medium shade tolerance · to −23 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Fsummer grape30 ft · blooms late spring · low shade tolerance · to −23 °Ftrumpet honeysuckle16 ft · blooms late summer · low shade tolerance · to −33 °F

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 Joliet, IL.

Soil in Joliet, IL

The soil mapped at the center of ZIP 60434 is Romeo — silt loam, poorly drained.

TextureSilt loama good balance for most vegetables
pH7.3neutral; most vegetables like 6.0–7.0
DrainagePoorly drainedconsider raised beds
Organic matter4%moderate
Hydrologic groupC/Dslow when drained; wet otherwise
Farmland classNot prime farmlandUSDA classification

Map unit: Romeo silt loam, 0 to 2 percent slopes.

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 60434; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Joliet, IL

Summer high84 °Faverage high, July
Winter low17 °Faverage low, January
Hot days15days a year at 90 °F or more
Freezing nights126nights a year at 32 °F or less
Growing degree days3,179base 50 °F — the season’s usable heat
Longest day15 h 11 mindaylight on June 21
Shortest day9 h 10 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation38 inper year, rain and melted snow
Snowfall17 inper year; 28 days with snow on the ground

Average high and low, by month

10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 31 °F, low 17 °F 31°17° JanFebruary: average high 35 °F, low 20 °F 35°20° FebMarch: average high 47 °F, low 29 °F 47°29° MarApril: average high 60 °F, low 39 °F 60°39° AprMay: average high 71 °F, low 49 °F 71°49° MayJune: average high 80 °F, low 60 °F 80°60° JunJuly: average high 84 °F, low 64 °F 84°64° JulAugust: average high 82 °F, low 63 °F 82°63° AugSeptember: average high 76 °F, low 55 °F 76°55° SepOctober: average high 63 °F, low 43 °F 63°43° OctNovember: average high 49 °F, low 32 °F 49°32° NovDecember: average high 36 °F, low 22 °F 36°22° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″January: 1.99 in precipitation, 5 in snowfall 2.0❄5 JanFebruary: 1.78 in precipitation, 6.2 in snowfall 1.8❄6 FebMarch: 2.27 in precipitation, 2.1 in snowfall 2.3❄2 MarApril: 3.93 in precipitation, 0.1 in snowfall 3.9 AprMay: 4.53 in precipitation 4.5 MayJune: 4.30 in precipitation 4.3 JunJuly: 4.55 in precipitation 4.5 JulAugust: 3.97 in precipitation 4.0 AugSeptember: 3.17 in precipitation 3.2 SepOctober: 3.14 in precipitation 3.1 OctNovember: 2.46 in precipitation, 0.3 in snowfall 2.5 NovDecember: 1.94 in precipitation, 3.2 in snowfall 1.9❄3 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Joliet Brandon Rd Dam, IL (2 mi away); precipitation: Joliet Brandon Rd Dam, IL (2 mi away). Daylight is calculated from latitude.

ZIP codes in Joliet

604315b
−15 to −10 °F
604326a
−10 to −5 °F
604336a
−10 to −5 °F
604346a
−10 to −5 °F
604356a
−10 to −5 °F
604366a
−10 to −5 °F

Illinois planting zones →

Questions about Joliet

What planting zone is Joliet, IL?

Joliet, IL is in USDA hardiness zones 5b to 6a on the 2023 map (5b: −15 to −10 °F; 6a: −10 to −5 °F).

When is the last frost in Joliet, IL?

The median last spring frost is April 19 and the median first fall frost is October 25 (NOAA 1991–2020 normals, Joliet Brandon Rd Dam station).

When can I plant a garden in Joliet, IL?

Cool-season crops like peas and spinach go in around Mar 8 – Mar 29; tomatoes, peppers, beans and squash after about Apr 26, once frost risk has passed.

What kind of onions grow in Joliet, IL?

Long-day onions: the longest day is 15 h 11 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

How much rain and snow does Joliet, IL get?

About 38 inches of precipitation a year and 17 inches of snowfall (NOAA 1991–2020 normals).