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

Planting zone for 52245 — Iowa City, IA

ZIP code 52245 (Iowa City, Johnson County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is April 21 and the first fall frost October 18.

Where ZIP 52245 is

Outlined: the ZIP code area · 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
Coldest night−26.1 to −23.3 °C
Last frostApr 21
First frostOct 18
2012 zone5b

Same zone as on the 2012 map. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 5b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Iowa City, IA…

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 Iowa City, IA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 21median — 50% chance of a later frost
Safe for tender plantsMay 6only 10% chance of frost after
First fall frostOctober 18median — 10% chance by Oct 4
Growing season180 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 9 and returns around October 28.

From the NOAA station Iowa City Municipal Airport, IA — 3 miles away, elevation 650 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 52245

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 10 – Mar 24
SpinachSow outdoors · Mar 10 – Mar 31
Broccoli, cabbageStart indoors · Feb 10 – Feb 24
Broccoli, cabbageTransplant · Mar 31 – Apr 14
Onion setsPlant outdoors · Mar 24 – Apr 7
PotatoesPlant outdoors · Mar 31 – Apr 14
LettuceSow outdoors · Mar 24 – Apr 7
Carrots, beetsSow outdoors · Mar 31 – Apr 14
TomatoesStart indoors · Feb 24 – Mar 10
TomatoesTransplant · Apr 28 – May 12
Peppers, eggplantStart indoors · Feb 10 – Feb 24
Peppers, eggplantTransplant · May 5 – May 19
BeansSow outdoors · Apr 28 – May 12
Sweet cornSow outdoors · Apr 28 – May 12
Cucumbers, squashSow outdoors · Apr 28 – May 12
Fall lettuce, spinachSow outdoors · Aug 23 – Sep 6
GarlicPlant cloves · Oct 4 – Nov 8
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 21) and first fall frost (Oct 18) 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 52245 came on Mar 25 — 11 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 Iowa

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

Trees 49

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °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 °Fbalsam fir60 ft · blooms mid summer · low shade tolerance · to −43 °F

Shrubs 77

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 hornbeam30 ft · blooms mid spring · low shade tolerance · to −34 °F

Wildflowers & perennials 191

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 136

arctic brome3 ft · blooms early summer · low shade tolerance · to −33 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °FBebb's sedge3 ft · blooms late spring · low shade tolerance · to −38 °FBicknell's sedge3 ft · blooms late spring · low shade tolerance · to −38 °Fbig bluestem6 ft · blooms summer · high shade tolerance · to −46 °Fblue grama1 ft · blooms early summer · high shade tolerance · to −43 °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 Iowa City, IA.

Soil in Iowa City, IA

The soil mapped at the center of ZIP 52245 is Fayette — silty clay loam, well drained.

TextureSilty clay loamholds water and nutrients; slow to drain and warm up
pH6.2slightly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter1.5%low — add compost
Hydrologic groupCwater soaks in slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Fayette silty clay loam, till plain, 14 to 18 percent slopes, severely eroded.

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 52245; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Iowa City, IA

Summer high86 °Faverage high, July
Winter low15 °Faverage low, January
Hot days19days a year at 90 °F or more
Freezing nights135nights a year at 32 °F or less
Growing degree days3,441base 50 °F — the season’s usable heat
Longest day15 h 12 mindaylight on June 21
Shortest day9 h 09 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation35.7 inper year, rain and melted snow

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 31 °F, low 15 °F 31°15° JanFebruary: average high 36 °F, low 19 °F 36°19° FebMarch: average high 50 °F, low 30 °F 50°30° MarApril: average high 63 °F, low 40 °F 63°40° AprMay: average high 73 °F, low 52 °F 73°52° MayJune: average high 83 °F, low 62 °F 83°62° JunJuly: average high 86 °F, low 66 °F 86°66° JulAugust: average high 84 °F, low 63 °F 84°63° AugSeptember: average high 78 °F, low 54 °F 78°54° SepOctober: average high 64 °F, low 42 °F 64°42° 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: 1.04 in precipitation 1.0 JanFebruary: 1.21 in precipitation 1.2 FebMarch: 2.21 in precipitation 2.2 MarApril: 3.76 in precipitation 3.8 AprMay: 4.48 in precipitation 4.5 MayJune: 5.29 in precipitation 5.3 JunJuly: 3.91 in precipitation 3.9 JulAugust: 3.94 in precipitation 3.9 AugSeptember: 3.24 in precipitation 3.2 SepOctober: 2.98 in precipitation 3.0 OctNovember: 2.17 in precipitation 2.2 NovDecember: 1.45 in precipitation 1.4 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Iowa City Municipal Airport, IA (3 mi away); precipitation: Iowa City Municipal Airport, IA (3 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 5b.

522435b
Iowa City, IA · 1 mi
522425b
Iowa City, IA · 2 mi
522405b
Iowa City, IA · 3 mi
522465b
Iowa City, IA · 5 mi
522415b
Coralville, IA · 5 mi
522355b
Hills, IA · 7 mi
523405b
Tiffin, IA · 9 mi
523175b
North Liberty, IA · 9 mi

All 6 ZIP codes in Iowa City → · Iowa planting zones →

Questions about 52245

What planting zone is ZIP code 52245?

ZIP code 52245 (Iowa City, IA) is in USDA hardiness zone 5b on the 2023 map: the coldest night of an average winter reaches −15 to −10 °F (−26.1 to −23.3 °C).

When is the last frost in Iowa City, IA?

The median last spring frost (32 °F) near 52245 is April 21; after May 6 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Iowa City Municipal Airport station.

When is the first frost in Iowa City, IA?

The median first fall frost near 52245 is October 18, giving a median frost-free growing season of 180 days.

When should I plant tomatoes in 52245?

Start tomato seeds indoors around Feb 24 – Mar 10 and set transplants outside around Apr 28 – May 12, one to three weeks after the median last frost.

How much rain and snow does 52245 get?

About 35.7 inches of precipitation a year (NOAA 1991–2020 normals, Iowa City Municipal Airport station).

How hot do summers get in Iowa City, IA?

The average high peaks at 86 °F in July, with about 19 days a year at 90 °F or more.

What kind of soil does 52245 have?

The USDA soil survey maps Fayette at the center of ZIP 52245: silty clay loam, well drained, pH about 6.2 (slightly acidic).

Did spring come early in Iowa City, IA in 2026?

Spring leaf-out near 52245 came on Mar 25 in 2026, 11 days earlier than the 1991–2020 average (Apr 5), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Iowa City, IA?

Long-day onions: the longest day near 52245 is 15 h 12 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).