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

Planting zone for 50658 — Nashua, IA

ZIP code 50658 (Nashua, Chickasaw County) is in USDA zone 5a: the coldest winter night averages −20 to −15 °F. The median last spring frost is April 30 and the first fall frost October 6.

Where ZIP 50658 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.

Zone5a−20 to −15 °F

Coldest night−28.9 to −26.1 °C

Last frostApr 30

First frostOct 6

2012 zone5a

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 5a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Nashua, 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 Nashua, IA

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 30median — 50% chance of a later frost

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

First fall frostOctober 6median — 10% chance by Sep 21

Growing season157 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 21 and returns around October 17.

From the NOAA station Charles City, IA — 10 miles away, elevation 994 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 50658

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 19 – Apr 2

SpinachSow outdoors · Mar 19 – Apr 9

Broccoli, cabbageStart indoors · Feb 19 – Mar 5

Broccoli, cabbageTransplant · Apr 9 – Apr 23

Onion setsPlant outdoors · Apr 2 – Apr 16

PotatoesPlant outdoors · Apr 9 – Apr 23

LettuceSow outdoors · Apr 2 – Apr 16

Carrots, beetsSow outdoors · Apr 9 – Apr 23

TomatoesStart indoors · Mar 5 – Mar 19

TomatoesTransplant · May 7 – May 21

Peppers, eggplantStart indoors · Feb 19 – Mar 5

Peppers, eggplantTransplant · May 14 – May 28

BeansSow outdoors · May 7 – May 21

Sweet cornSow outdoors · May 7 – May 21

Cucumbers, squashSow outdoors · May 7 – May 21

Fall lettuce, spinachSow outdoors · Aug 11 – Aug 25

GarlicPlant cloves · Sep 22 – Oct 27

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 30) and first fall frost (Oct 6) 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 50658 came on Mar 28 — 15 days earlier than the 1991–2020 average (Apr 12).

average
Apr 122026
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 5a in Iowa

461 plants native to the lower 48 states, recorded in Iowa, and rated by the USDA to survive −20 °F or colder — the bottom of zone 5a. 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 Nashua, IA.

Soil in Nashua, IA

The soil mapped at the center of ZIP 50658 is Rockton — loam, well drained.

TextureLoama good balance for most vegetables

pH6.6neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter3.5%moderate

Hydrologic groupCwater soaks in slowly

Farmland classprime farmlandUSDA classification

Map unit: Rockton loam, 30 to 40 inches to limestone, till plain, 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 50658; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Nashua, IA

Summer high82 °Faverage high, July

Winter low9 °Faverage low, January

Hot days9days a year at 90 °F or more

Freezing nights154nights a year at 32 °F or less

Growing degree days2,754base 50 °F — the season’s usable heat

Longest day15 h 21 mindaylight on June 21

Shortest day9 h 00 mindaylight on December 21

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

Precipitation38.1 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Charles City, IA (10 mi away); precipitation: Nashua 2 Sw, IA (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 5a.

506455a

Ionia, IA · 7 mi

506665a

Plainfield, IA · 7 mi

506165a

Charles City, IA · 11 mi

506195a

Clarksville, IA · 12 mi

506315a

Frederika, IA · 12 mi

506615a

North Washington, IA · 13 mi

Iowa planting zones →

Questions about 50658

What planting zone is ZIP code 50658?

ZIP code 50658 (Nashua, IA) is in USDA hardiness zone 5a on the 2023 map: the coldest night of an average winter reaches −20 to −15 °F (−28.9 to −26.1 °C).

When is the last frost in Nashua, IA?

The median last spring frost (32 °F) near 50658 is April 30; after May 14 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Charles City station.

When is the first frost in Nashua, IA?

The median first fall frost near 50658 is October 6, giving a median frost-free growing season of 157 days.

When should I plant tomatoes in 50658?

Start tomato seeds indoors around Mar 5 – Mar 19 and set transplants outside around May 7 – May 21, one to three weeks after the median last frost.

How much rain and snow does 50658 get?

About 38.1 inches of precipitation a year (NOAA 1991–2020 normals, Nashua 2 Sw station).

How hot do summers get in Nashua, 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 50658 have?

The USDA soil survey maps Rockton at the center of ZIP 50658: loam, well drained, pH about 6.6 (neutral).

Did spring come early in Nashua, IA in 2026?

Spring leaf-out near 50658 came on Mar 28 in 2026, 15 days earlier than the 1991–2020 average (Apr 12), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Nashua, IA?

Long-day onions: the longest day near 50658 is 15 h 21 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).