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

Planting zone for 50137 — Killduff, IA

ZIP code 50137 (Killduff, Jasper County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is April 22 and the first fall frost October 17.

Where ZIP 50137 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 22
First frostOct 17
2012 zone5a

Was 5a on the 2012 map — half a zone warmer now. 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 Killduff, 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 Killduff, IA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 22median — 50% chance of a later frost
Safe for tender plantsMay 4only 10% chance of frost after
First fall frostOctober 17median — 10% chance by Oct 1
Growing season174 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 12 and returns around October 26.

From the NOAA station Newton, IA — 9 miles away, elevation 961 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 50137

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 11 – Mar 25
SpinachSow outdoors · Mar 11 – Apr 1
Broccoli, cabbageStart indoors · Feb 11 – Feb 25
Broccoli, cabbageTransplant · Apr 1 – Apr 15
Onion setsPlant outdoors · Mar 25 – Apr 8
PotatoesPlant outdoors · Apr 1 – Apr 15
LettuceSow outdoors · Mar 25 – Apr 8
Carrots, beetsSow outdoors · Apr 1 – Apr 15
TomatoesStart indoors · Feb 25 – Mar 11
TomatoesTransplant · Apr 29 – May 13
Peppers, eggplantStart indoors · Feb 11 – Feb 25
Peppers, eggplantTransplant · May 6 – May 20
BeansSow outdoors · Apr 29 – May 13
Sweet cornSow outdoors · Apr 29 – May 13
Cucumbers, squashSow outdoors · Apr 29 – May 13
Fall lettuce, spinachSow outdoors · Aug 22 – Sep 5
GarlicPlant cloves · Oct 3 – Nov 7
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 22) and first fall frost (Oct 17) 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 50137 came on Mar 23 — 13 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 Killduff, IA.

Soil in Killduff, IA

The soil mapped at the center of ZIP 50137 is Caleb — loam, moderately well drained.

TextureLoama good balance for most vegetables
pH5.9moderately acidic; most vegetables like 6.0–7.0
DrainageModerately well drainednatural drainage class
Organic matter2.5%moderate
Hydrologic groupCwater soaks in slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Caleb and mystic soils, 14 to 18 percent slopes, moderately 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 50137; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Killduff, IA

Summer high85 °Faverage high, July
Winter low10 °Faverage low, January
Hot days21days a year at 90 °F or more
Freezing nights142nights a year at 32 °F or less
Growing degree days3,112base 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)
Precipitation35.1 inper year, rain and melted snow
Snowfall29 inper year

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 28 °F, low 10 °F 28°10° JanFebruary: average high 33 °F, low 14 °F 33°14° FebMarch: average high 46 °F, low 26 °F 46°26° MarApril: average high 60 °F, low 37 °F 60°37° AprMay: average high 71 °F, low 50 °F 71°50° MayJune: average high 81 °F, low 60 °F 81°60° JunJuly: average high 85 °F, low 64 °F 85°64° JulAugust: average high 83 °F, low 61 °F 83°61° AugSeptember: average high 76 °F, low 52 °F 76°52° SepOctober: average high 63 °F, low 40 °F 63°40° OctNovember: average high 47 °F, low 27 °F 47°27° NovDecember: average high 34 °F, low 17 °F 34°17° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″6″January: 0.93 in precipitation, 9.2 in snowfall 0.9❄9 JanFebruary: 1.10 in precipitation, 6 in snowfall 1.1❄6 FebMarch: 2.06 in precipitation, 4.5 in snowfall 2.1❄5 MarApril: 3.44 in precipitation, 0.8 in snowfall 3.4❄1 AprMay: 4.84 in precipitation 4.8 MayJune: 5.01 in precipitation 5.0 JunJuly: 3.93 in precipitation 3.9 JulAugust: 4.30 in precipitation 4.3 AugSeptember: 3.59 in precipitation 3.6 SepOctober: 2.66 in precipitation, 0.3 in snowfall 2.7 OctNovember: 2.01 in precipitation, 1.6 in snowfall 2.0❄2 NovDecember: 1.27 in precipitation, 6.3 in snowfall 1.3❄6 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Newton, IA (9 mi away); precipitation: Newton, IA (9 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 5b.

502515b
Sully, IA · 4 mi
502325b
Reasnor, IA · 4 mi
501535b
Lynnville, IA · 6 mi
502085b
Newton, IA · 9 mi
501355b
Kellogg, IA · 9 mi
501705b
Monroe, IA · 11 mi
502145b
Otley, IA · 12 mi
502425b
Searsboro, IA · 12 mi

Iowa planting zones →

Questions about 50137

What planting zone is ZIP code 50137?

ZIP code 50137 (Killduff, 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 Killduff, IA?

The median last spring frost (32 °F) near 50137 is April 22; after May 4 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Newton station.

When is the first frost in Killduff, IA?

The median first fall frost near 50137 is October 17, giving a median frost-free growing season of 174 days.

When should I plant tomatoes in 50137?

Start tomato seeds indoors around Feb 25 – Mar 11 and set transplants outside around Apr 29 – May 13, one to three weeks after the median last frost.

How much rain and snow does 50137 get?

About 35.1 inches of precipitation a year and 29 inches of snowfall (NOAA 1991–2020 normals, Newton station).

How hot do summers get in Killduff, IA?

The average high peaks at 85 °F in July, with about 21 days a year at 90 °F or more.

What kind of soil does 50137 have?

The USDA soil survey maps Caleb at the center of ZIP 50137: loam, moderately well drained, pH about 5.9 (moderately acidic).

Did spring come early in Killduff, IA in 2026?

Spring leaf-out near 50137 came on Mar 23 in 2026, 13 days earlier than the 1991–2020 average (Apr 5), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Killduff, IA?

Long-day onions: the longest day near 50137 is 15 h 12 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 50137 change?

Yes. The 2012 USDA map put 50137 in zone 5a; the 2023 map puts it in zone 5b. The newer map uses 1991–2020 data and more weather stations.