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

Planting zone for 52235 — Hills, IA

ZIP code 52235 (Hills, Johnson County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is April 29 and the first fall frost October 9.

Where ZIP 52235 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 29

First frostOct 9

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 Hills, 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 Hills, IA

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 29median — 50% chance of a later frost

Safe for tender plantsMay 14only 10% chance of frost after

First fall frostOctober 9median — 10% chance by Sep 25

Growing season162 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 18 and returns around October 20.

From the NOAA station Iowa City, IA — 2 miles away, elevation 640 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 52235

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 18 – Apr 1

SpinachSow outdoors · Mar 18 – Apr 8

Broccoli, cabbageStart indoors · Feb 18 – Mar 4

Broccoli, cabbageTransplant · Apr 8 – Apr 22

Onion setsPlant outdoors · Apr 1 – Apr 15

PotatoesPlant outdoors · Apr 8 – Apr 22

LettuceSow outdoors · Apr 1 – Apr 15

Carrots, beetsSow outdoors · Apr 8 – Apr 22

TomatoesStart indoors · Mar 4 – Mar 18

TomatoesTransplant · May 6 – May 20

Peppers, eggplantStart indoors · Feb 18 – Mar 4

Peppers, eggplantTransplant · May 13 – May 27

BeansSow outdoors · May 6 – May 20

Sweet cornSow outdoors · May 6 – May 20

Cucumbers, squashSow outdoors · May 6 – May 20

Fall lettuce, spinachSow outdoors · Aug 14 – Aug 28

GarlicPlant cloves · Sep 25 – Oct 30

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 29) and first fall frost (Oct 9) 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 52235 came on Mar 20 — 15 days earlier than the 1991–2020 average (Apr 4).

average
Apr 42026
Mar 20

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).

Soil in Hills, IA

The soil mapped at the center of ZIP 52235 is Lawson — silt loam, somewhat poorly drained.

TextureSilt loama good balance for most vegetables

pH6.7neutral; most vegetables like 6.0–7.0

DrainageSomewhat poorly drainedconsider raised beds

Organic matter5%high

Hydrologic groupB/Dmoderate when drained; wet otherwise

Farmland classprime farmlandUSDA classification

Map unit: Lawson silt loam, 0 to 2 percent slopes, occasionally flooded.

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 52235; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Hills, IA

Summer high84 °Faverage high, July

Winter low12 °Faverage low, January

Hot days24days a year at 90 °F or more

Freezing nights130nights a year at 32 °F or less

Growing degree days3,049base 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)

Precipitation38.5 inper year, rain and melted snow

Snowfall28 inper year; 48 days with snow on the ground

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Iowa City, IA (2 mi away); precipitation: Iowa City, IA (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 5b.

Iowa planting zones →

Questions about 52235

What planting zone is ZIP code 52235?

ZIP code 52235 (Hills, 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 Hills, IA?

The median last spring frost (32 °F) near 52235 is April 29; after May 14 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Iowa City station.

When is the first frost in Hills, IA?

The median first fall frost near 52235 is October 9, giving a median frost-free growing season of 162 days.

When should I plant tomatoes in 52235?

Start tomato seeds indoors around Mar 4 – Mar 18 and set transplants outside around May 6 – May 20, one to three weeks after the median last frost.

How much rain and snow does 52235 get?

About 38.5 inches of precipitation a year and 28 inches of snowfall (NOAA 1991–2020 normals, Iowa City station).

How hot do summers get in Hills, IA?

The average high peaks at 84 °F in July, with about 24 days a year at 90 °F or more.

What kind of soil does 52235 have?

The USDA soil survey maps Lawson at the center of ZIP 52235: silt loam, somewhat poorly drained, pH about 6.7 (neutral).

Did spring come early in Hills, IA in 2026?

Spring leaf-out near 52235 came on Mar 20 in 2026, 15 days earlier than the 1991–2020 average (Apr 4), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Hills, IA?

Long-day onions: the longest day near 52235 is 15 h 12 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).