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

Planting zone for Rock Island, IL

Rock Island, IL is in USDA zone 5b across its 3 ZIP codes. The median last spring frost is April 19 and the first fall frost October 22.

Rock Island on the zone map

Outlined: its 1 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.

Zone5b−15 to −10 °F
ZIP codes3
Last frostApr 19
First frostOct 22
Growing season184 days

5b 3 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 Rock Island, 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 4only 10% chance of frost after
First fall frostOctober 22median — 10% chance by Oct 7
Growing season184 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 8 and returns around October 31.

From the NOAA station Rock Island L&D 15, IL, elevation 568 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 Rock Island

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 27 – Sep 10
GarlicPlant cloves · Oct 8 – Nov 12
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 19) and first fall frost (Oct 22) 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 61299 came on Mar 20 — 15 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 Rock Island, IL.

Soil in Rock Island, IL

The soil mapped at the center of ZIP 61299 is Coyne — fine sandy loam, well drained.

TextureFine sandy loamdrains and warms fast; dries out and needs more feeding
pH6.5neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter3%moderate
Hydrologic groupBwater soaks in moderately
Farmland classNot prime farmlandUSDA classification

Map unit: Coyne fine sandy loam, 5 to 10 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 61299; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Rock Island, IL

Summer high84 °Faverage high, July
Winter low13 °Faverage low, January
Hot days18days a year at 90 °F or more
Freezing nights118nights a year at 32 °F or less
Growing degree days3,293base 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)
Precipitation38.8 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 31 °F, low 13 °F 31°13° JanFebruary: average high 36 °F, low 18 °F 36°18° FebMarch: average high 48 °F, low 28 °F 48°28° MarApril: average high 61 °F, low 39 °F 61°39° AprMay: average high 72 °F, low 51 °F 72°51° MayJune: average high 81 °F, low 61 °F 81°61° JunJuly: average high 84 °F, low 65 °F 84°65° JulAugust: average high 82 °F, low 63 °F 82°63° AugSeptember: average high 77 °F, low 55 °F 77°55° SepOctober: average high 64 °F, low 43 °F 64°43° OctNovember: average high 49 °F, low 30 °F 49°30° NovDecember: average high 36 °F, low 20 °F 36°20° Dec

Precipitation by month inches

0″1″2″3″4″5″6″January: 1.49 in precipitation 1.5 JanFebruary: 1.78 in precipitation 1.8 FebMarch: 2.62 in precipitation 2.6 MarApril: 3.81 in precipitation 3.8 AprMay: 5.12 in precipitation 5.1 MayJune: 5.22 in precipitation 5.2 JunJuly: 4.22 in precipitation 4.2 JulAugust: 4.03 in precipitation 4.0 AugSeptember: 3.31 in precipitation 3.3 SepOctober: 2.89 in precipitation 2.9 OctNovember: 2.30 in precipitation 2.3 NovDecember: 2.02 in precipitation 2.0 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Rock Island L&D 15, IL (within 1 mile); precipitation: Rock Island L&D 15, IL (within 1 mile). Daylight is calculated from latitude.

ZIP codes in Rock Island

612015b
−15 to −10 °F
612045b
−15 to −10 °F
612995b
−15 to −10 °F

Illinois planting zones →

Questions about Rock Island

What planting zone is Rock Island, IL?

Rock Island, IL is in USDA hardiness zone 5b on the 2023 map (5b: −15 to −10 °F).

When is the last frost in Rock Island, IL?

The median last spring frost is April 19 and the median first fall frost is October 22 (NOAA 1991–2020 normals, Rock Island L&D 15 station).

When can I plant a garden in Rock Island, 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 Rock Island, 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 Rock Island, IL get?

About 38.8 inches of precipitation a year (NOAA 1991–2020 normals).