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

Planting zone for 52036 — Delaware, IA

ZIP code 52036 (Delaware, Delaware County) is in USDA zone 4b: the coldest winter night averages −25 to −20 °F. The median last spring frost is May 3 and the first fall frost October 4.

Where ZIP 52036 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.

Zone4b−25 to −20 °F

Coldest night−31.7 to −28.9 °C

Last frostMay 3

First frostOct 4

2012 zone5a

Was 5a on the 2012 map — half a zone colder now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 4b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Delaware, 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 Delaware, IA

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 3median — 50% chance of a later frost

Safe for tender plantsMay 16only 10% chance of frost after

First fall frostOctober 4median — 10% chance by Sep 22

Growing season154 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 23 and returns around October 15.

From the NOAA station Manchester #2, IA — 6 miles away, elevation 991 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 52036

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 22 – Apr 5

SpinachSow outdoors · Mar 22 – Apr 12

Broccoli, cabbageStart indoors · Feb 22 – Mar 8

Broccoli, cabbageTransplant · Apr 12 – Apr 26

Onion setsPlant outdoors · Apr 5 – Apr 19

PotatoesPlant outdoors · Apr 12 – Apr 26

LettuceSow outdoors · Apr 5 – Apr 19

Carrots, beetsSow outdoors · Apr 12 – Apr 26

TomatoesStart indoors · Mar 8 – Mar 22

TomatoesTransplant · May 10 – May 24

Peppers, eggplantStart indoors · Feb 22 – Mar 8

Peppers, eggplantTransplant · May 17 – May 31

BeansSow outdoors · May 10 – May 24

Sweet cornSow outdoors · May 10 – May 24

Cucumbers, squashSow outdoors · May 10 – May 24

Fall lettuce, spinachSow outdoors · Aug 9 – Aug 23

GarlicPlant cloves · Sep 20 – Oct 25

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 3) and first fall frost (Oct 4) 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 52036 came on Mar 25 — 18 days earlier than the 1991–2020 average (Apr 12).

average
Apr 122026
Mar 25

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 4b in Iowa

426 plants native to the lower 48 states, recorded in Iowa, and rated by the USDA to survive −25 °F or colder — the bottom of zone 4b. Each links to its USDA PLANTS profile.

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 Delaware, IA.

Soil in Delaware, IA

The soil mapped at the center of ZIP 52036 is Bassett — loam, moderately well drained.

TextureLoama good balance for most vegetables

pH6.2slightly acidic; most vegetables like 6.0–7.0

DrainageModerately well drainednatural drainage class

Organic matter2.4%moderate

Hydrologic groupCwater soaks in slowly

Farmland classprime farmlandUSDA classification

Map unit: Bassett loam, 2 to 5 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 52036; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Delaware, IA

Summer high82 °Faverage high, July

Winter low8 °Faverage low, January

Hot days9days a year at 90 °F or more

Freezing nights158nights a year at 32 °F or less

Growing degree days2,660base 50 °F — the season’s usable heat

Longest day15 h 18 mindaylight on June 21

Shortest day9 h 04 mindaylight on December 21

Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)

Precipitation38.6 inper year, rain and melted snow

Snowfall35 inper year; 66 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: Manchester #2, IA (6 mi away); precipitation: Manchester #2, IA (6 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

7 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

Manchester, IA · 6 mi

520504b

Greeley, IA · 10 mi

522375a

Hopkinton, IA · 10 mi

520405a

Dyersville, IA · 10 mi

523305a

Ryan, IA · 12 mi

520785a

Worthington, IA · 13 mi

Iowa planting zones →

Questions about 52036

What planting zone is ZIP code 52036?

ZIP code 52036 (Delaware, IA) is in USDA hardiness zone 4b on the 2023 map: the coldest night of an average winter reaches −25 to −20 °F (−31.7 to −28.9 °C).

When is the last frost in Delaware, IA?

The median last spring frost (32 °F) near 52036 is May 3; after May 16 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Manchester #2 station.

When is the first frost in Delaware, IA?

The median first fall frost near 52036 is October 4, giving a median frost-free growing season of 154 days.

When should I plant tomatoes in 52036?

Start tomato seeds indoors around Mar 8 – Mar 22 and set transplants outside around May 10 – May 24, one to three weeks after the median last frost.

How much rain and snow does 52036 get?

About 38.6 inches of precipitation a year and 35 inches of snowfall (NOAA 1991–2020 normals, Manchester #2 station).

How hot do summers get in Delaware, IA?

The average high peaks at 82 °F in July, with about 9 days a year at 90 °F or more.

What kind of soil does 52036 have?

The USDA soil survey maps Bassett at the center of ZIP 52036: loam, moderately well drained, pH about 6.2 (slightly acidic).

Did spring come early in Delaware, IA in 2026?

Spring leaf-out near 52036 came on Mar 25 in 2026, 18 days earlier than the 1991–2020 average (Apr 12), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Delaware, IA?

Long-day onions: the longest day near 52036 is 15 h 18 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 52036 change?

Yes. The 2012 USDA map put 52036 in zone 5a; the 2023 map puts it in zone 4b. The newer map uses 1991–2020 data and more weather stations.