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

Planting zone for 51601 — Shenandoah, IA

ZIP code 51601 (Shenandoah, Page County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is April 20 and the first fall frost October 17.

Where ZIP 51601 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 20
First frostOct 17
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 Shenandoah, 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 Shenandoah, IA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 20median — 50% chance of a later frost
Safe for tender plantsMay 3only 10% chance of frost after
First fall frostOctober 17median — 10% chance by Oct 1
Growing season179 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 9 and returns around October 26.

From the NOAA station Shenandoah, IA — 2 miles away, elevation 1,001 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 51601

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 9 – Mar 23
SpinachSow outdoors · Mar 9 – Mar 30
Broccoli, cabbageStart indoors · Feb 9 – Feb 23
Broccoli, cabbageTransplant · Mar 30 – Apr 13
Onion setsPlant outdoors · Mar 23 – Apr 6
PotatoesPlant outdoors · Mar 30 – Apr 13
LettuceSow outdoors · Mar 23 – Apr 6
Carrots, beetsSow outdoors · Mar 30 – Apr 13
TomatoesStart indoors · Feb 23 – Mar 9
TomatoesTransplant · Apr 27 – May 11
Peppers, eggplantStart indoors · Feb 9 – Feb 23
Peppers, eggplantTransplant · May 4 – May 18
BeansSow outdoors · Apr 27 – May 11
Sweet cornSow outdoors · Apr 27 – May 11
Cucumbers, squashSow outdoors · Apr 27 – May 11
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 20) 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 51601 came on Mar 11 — 17 days earlier than the 1991–2020 average (Mar 28).

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 Shenandoah, IA.

Soil in Shenandoah, IA

The soil mapped at the center of ZIP 51601 is Exira — silty clay loam, well drained.

TextureSilty clay loamholds water and nutrients; slow to drain and warm up
pH6.4slightly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2.6%moderate
Hydrologic groupCwater soaks in slowly
Farmland classFarmland of statewide importanceUSDA classification

Map unit: Exira silty clay loam, 5 to 9 percent slopes, 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 51601; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Shenandoah, IA

Summer high87 °Faverage high, July
Winter low14 °Faverage low, January
Hot days32days a year at 90 °F or more
Freezing nights137nights a year at 32 °F or less
Growing degree days3,644base 50 °F — the season’s usable heat
Longest day15 h 06 mindaylight on June 21
Shortest day9 h 15 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation36.4 inper year, rain and melted snow
Snowfall26 inper year; 43 days with snow on the ground

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 33 °F, low 14 °F 33°14° JanFebruary: average high 39 °F, low 18 °F 39°18° FebMarch: average high 52 °F, low 29 °F 52°29° MarApril: average high 64 °F, low 40 °F 64°40° AprMay: average high 74 °F, low 53 °F 74°53° MayJune: average high 83 °F, low 63 °F 83°63° JunJuly: average high 87 °F, low 67 °F 87°67° JulAugust: average high 85 °F, low 64 °F 85°64° AugSeptember: average high 79 °F, low 55 °F 79°55° SepOctober: average high 66 °F, low 42 °F 66°42° OctNovember: average high 51 °F, low 29 °F 51°29° NovDecember: average high 38 °F, low 19 °F 38°19° Dec

Precipitation by month inches · ❄ = snowfall

0″2″4″6″January: 0.92 in precipitation, 7 in snowfall 0.9❄7 JanFebruary: 1.21 in precipitation, 7.5 in snowfall 1.2❄8 FebMarch: 2.06 in precipitation, 2.8 in snowfall 2.1❄3 MarApril: 3.34 in precipitation, 1.2 in snowfall 3.3❄1 AprMay: 6.16 in precipitation 6.2 MayJune: 5.53 in precipitation 5.5 JunJuly: 4.36 in precipitation 4.4 JulAugust: 3.77 in precipitation 3.8 AugSeptember: 3.02 in precipitation 3.0 SepOctober: 2.84 in precipitation, 0.6 in snowfall 2.8❄1 OctNovember: 1.76 in precipitation, 1.5 in snowfall 1.8❄2 NovDecember: 1.40 in precipitation, 5.8 in snowfall 1.4❄6 Dec

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

Nearby ZIP codes

All 8 nearest ZIP codes share zone 5b.

516035b
Shenandoah, IA · 2 mi
516395b
Farragut, IA · 6 mi
516365b
Coin, IA · 8 mi
516385b
Essex, IA · 8 mi
516475b
Northboro, IA · 9 mi
516565b
Yorktown, IA · 10 mi
516455b
Imogene, IA · 11 mi
516505b
Riverton, IA · 11 mi

All 2 ZIP codes in Shenandoah → · Iowa planting zones →

Questions about 51601

What planting zone is ZIP code 51601?

ZIP code 51601 (Shenandoah, 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 Shenandoah, IA?

The median last spring frost (32 °F) near 51601 is April 20; after May 3 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Shenandoah station.

When is the first frost in Shenandoah, IA?

The median first fall frost near 51601 is October 17, giving a median frost-free growing season of 179 days.

When should I plant tomatoes in 51601?

Start tomato seeds indoors around Feb 23 – Mar 9 and set transplants outside around Apr 27 – May 11, one to three weeks after the median last frost.

How much rain and snow does 51601 get?

About 36.4 inches of precipitation a year and 26 inches of snowfall (NOAA 1991–2020 normals, Shenandoah station).

How hot do summers get in Shenandoah, IA?

The average high peaks at 87 °F in July, with about 32 days a year at 90 °F or more.

What kind of soil does 51601 have?

The USDA soil survey maps Exira at the center of ZIP 51601: silty clay loam, well drained, pH about 6.4 (slightly acidic).

Did spring come early in Shenandoah, IA in 2026?

Spring leaf-out near 51601 came on Mar 11 in 2026, 17 days earlier than the 1991–2020 average (Mar 28), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Shenandoah, IA?

Long-day onions: the longest day near 51601 is 15 h 06 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).