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

Planting zone for Downers Grove, IL

Downers Grove, IL is in USDA zones 5b to 6a across its 2 ZIP codes. The median last spring frost is April 28 and the first fall frost October 16.

Downers Grove on the zone map

Outlined: its 2 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 codes2
Last frostApr 28
First frostOct 16
Growing season169 days

5b 1 ZIP   6a 1 ZIP

Frost forecast — next 7 nights

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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 Downers Grove, IL

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 28median — 50% chance of a later frost
Safe for tender plantsMay 14only 10% chance of frost after
First fall frostOctober 16median — 10% chance by Oct 1
Growing season169 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 16 and returns around October 26.

From the NOAA station Lisle-Morton Arboretum, IL, elevation 679 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 Downers Grove

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 17 – Mar 31
SpinachSow outdoors · Mar 17 – Apr 7
Broccoli, cabbageStart indoors · Feb 17 – Mar 3
Broccoli, cabbageTransplant · Apr 7 – Apr 21
Onion setsPlant outdoors · Mar 31 – Apr 14
PotatoesPlant outdoors · Apr 7 – Apr 21
LettuceSow outdoors · Mar 31 – Apr 14
Carrots, beetsSow outdoors · Apr 7 – Apr 21
TomatoesStart indoors · Mar 3 – Mar 17
TomatoesTransplant · May 5 – May 19
Peppers, eggplantStart indoors · Feb 17 – Mar 3
Peppers, eggplantTransplant · May 12 – May 26
BeansSow outdoors · May 5 – May 19
Sweet cornSow outdoors · May 5 – May 19
Cucumbers, squashSow outdoors · May 5 – May 19
Fall lettuce, spinachSow outdoors · Aug 21 – Sep 4
GarlicPlant cloves · Oct 2 – Nov 6
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 28) and first fall frost (Oct 16) 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 60515 came on Mar 21 — 15 days earlier than the 1991–2020 average (Apr 5).

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 Downers Grove, IL.

Soil in Downers Grove, IL

The soil mapped at the center of ZIP 60515 is Markham — silt loam, moderately well drained.

TextureSilt loama good balance for most vegetables
pH5.8moderately acidic; most vegetables like 6.0–7.0
DrainageModerately well drainednatural drainage class
Organic matter3%moderate
Hydrologic groupCwater soaks in slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Markham-Ashkum-Beecher complex, 1 to 6 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 60515; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Downers Grove, IL

Summer high84 °Faverage high, July
Winter low15 °Faverage low, January
Hot days17days a year at 90 °F or more
Freezing nights144nights a year at 32 °F or less
Growing degree days2,957base 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)
Precipitation42.3 inper year, rain and melted snow

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 32 °F, low 15 °F 32°15° JanFebruary: average high 35 °F, low 18 °F 35°18° FebMarch: average high 47 °F, low 26 °F 47°26° MarApril: average high 59 °F, low 36 °F 59°36° AprMay: average high 71 °F, low 47 °F 71°47° MayJune: average high 81 °F, low 58 °F 81°58° JunJuly: average high 84 °F, low 62 °F 84°62° JulAugust: average high 83 °F, low 60 °F 83°60° AugSeptember: average high 76 °F, low 52 °F 76°52° SepOctober: average high 63 °F, low 40 °F 63°40° OctNovember: average high 48 °F, low 30 °F 48°30° NovDecember: average high 37 °F, low 21 °F 37°21° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 2.23 in precipitation 2.2 JanFebruary: 2.18 in precipitation 2.2 FebMarch: 2.59 in precipitation 2.6 MarApril: 3.88 in precipitation 3.9 AprMay: 4.87 in precipitation 4.9 MayJune: 4.91 in precipitation 4.9 JunJuly: 4.26 in precipitation 4.3 JulAugust: 4.62 in precipitation 4.6 AugSeptember: 3.28 in precipitation 3.3 SepOctober: 4.09 in precipitation 4.1 OctNovember: 2.91 in precipitation 2.9 NovDecember: 2.45 in precipitation 2.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Lisle-Morton Arboretum, IL (2 mi away); precipitation: Downers Grove 0.4 Nne, IL (within 1 mile). Daylight is calculated from latitude.

ZIP codes in Downers Grove

605156a
−10 to −5 °F
605165b
−15 to −10 °F

Illinois planting zones →

Questions about Downers Grove

What planting zone is Downers Grove, IL?

Downers Grove, 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 Downers Grove, IL?

The median last spring frost is April 28 and the median first fall frost is October 16 (NOAA 1991–2020 normals, Lisle-Morton Arboretum station).

When can I plant a garden in Downers Grove, IL?

Cool-season crops like peas and spinach go in around Mar 17 – Apr 7; tomatoes, peppers, beans and squash after about May 5, once frost risk has passed.

What kind of onions grow in Downers Grove, IL?

Long-day onions: the longest day is 15 h 13 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

How much rain and snow does Downers Grove, IL get?

About 42.3 inches of precipitation a year (NOAA 1991–2020 normals).