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

Planting zone for 50108 — Grand River, IA

ZIP code 50108 (Grand River, Decatur County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is April 23 and the first fall frost October 17.

Where ZIP 50108 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 23
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 Grand River, 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 Grand River, IA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 23median — 50% chance of a later frost
Safe for tender plantsMay 6only 10% chance of frost after
First fall frostOctober 17median — 10% chance by Oct 1
Growing season176 daysfrost-free, median

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

From the NOAA station Beaconsfield, IA — 4 miles away, elevation 1,214 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 50108

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 12 – Mar 26
SpinachSow outdoors · Mar 12 – Apr 2
Broccoli, cabbageStart indoors · Feb 12 – Feb 26
Broccoli, cabbageTransplant · Apr 2 – Apr 16
Onion setsPlant outdoors · Mar 26 – Apr 9
PotatoesPlant outdoors · Apr 2 – Apr 16
LettuceSow outdoors · Mar 26 – Apr 9
Carrots, beetsSow outdoors · Apr 2 – Apr 16
TomatoesStart indoors · Feb 26 – Mar 12
TomatoesTransplant · Apr 30 – May 14
Peppers, eggplantStart indoors · Feb 12 – Feb 26
Peppers, eggplantTransplant · May 7 – May 21
BeansSow outdoors · Apr 30 – May 14
Sweet cornSow outdoors · Apr 30 – May 14
Cucumbers, squashSow outdoors · Apr 30 – May 14
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 23) 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 50108 came on Mar 11 — 20 days earlier than the 1991–2020 average (Mar 31).

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 Grand River, IA.

Soil in Grand River, IA

The soil mapped at the center of ZIP 50108 is Mystic — clay loam, somewhat poorly drained.

TextureClay loamholds water and nutrients; slow to drain and warm up
pH5.9moderately acidic; most vegetables like 6.0–7.0
DrainageSomewhat poorly drainedconsider raised beds
Organic matter2.5%moderate
Hydrologic groupC/Dslow when drained; wet otherwise
Farmland classFarmland of statewide importanceUSDA classification

Map unit: Mystic clay loam, 5 to 9 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 50108; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Grand River, IA

Summer high84 °Faverage high, July
Winter low12 °Faverage low, January
Hot days13days a year at 90 °F or more
Freezing nights142nights a year at 32 °F or less
Growing degree days3,074base 50 °F — the season’s usable heat
Longest day15 h 06 mindaylight on June 21
Shortest day9 h 14 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation38 inper year, rain and melted snow
Snowfall27 inper year; 52 days with snow on the ground

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 30 °F, low 12 °F 30°12° JanFebruary: average high 36 °F, low 16 °F 36°16° FebMarch: average high 48 °F, low 27 °F 48°27° MarApril: average high 61 °F, low 38 °F 61°38° AprMay: average high 70 °F, low 50 °F 70°50° MayJune: average high 79 °F, low 60 °F 79°60° JunJuly: average high 84 °F, low 64 °F 84°64° JulAugust: average high 82 °F, low 62 °F 82°62° AugSeptember: average high 76 °F, low 53 °F 76°53° SepOctober: average high 63 °F, low 41 °F 63°41° OctNovember: average high 48 °F, low 28 °F 48°28° NovDecember: average high 36 °F, low 18 °F 36°18° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″6″January: 0.94 in precipitation, 7.2 in snowfall 0.9❄7 JanFebruary: 1.32 in precipitation, 6.2 in snowfall 1.3❄6 FebMarch: 2.19 in precipitation, 3.5 in snowfall 2.2❄4 MarApril: 4.05 in precipitation, 1.3 in snowfall 4.0❄1 AprMay: 5.27 in precipitation 5.3 MayJune: 5.27 in precipitation 5.3 JunJuly: 4.14 in precipitation 4.1 JulAugust: 4.10 in precipitation 4.1 AugSeptember: 4.11 in precipitation 4.1 SepOctober: 2.97 in precipitation, 0.5 in snowfall 3.0❄1 OctNovember: 2.12 in precipitation, 1.8 in snowfall 2.1❄2 NovDecember: 1.49 in precipitation, 6 in snowfall 1.5❄6 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Beaconsfield, IA (4 mi away); precipitation: Beaconsfield, IA (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 5b.

500745b
Ellston, IA · 7 mi
502625b
Van Wert, IA · 8 mi
501335b
Kellerton, IA · 10 mi
500675b
Decatur, IA · 10 mi
508635b
Tingley, IA · 11 mi
502545b
Thayer, IA · 13 mi
501405b
Lamoni, IA · 13 mi
501445b
Leon, IA · 14 mi

Iowa planting zones →

Questions about 50108

What planting zone is ZIP code 50108?

ZIP code 50108 (Grand River, 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 Grand River, IA?

The median last spring frost (32 °F) near 50108 is April 23; after May 6 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Beaconsfield station.

When is the first frost in Grand River, IA?

The median first fall frost near 50108 is October 17, giving a median frost-free growing season of 176 days.

When should I plant tomatoes in 50108?

Start tomato seeds indoors around Feb 26 – Mar 12 and set transplants outside around Apr 30 – May 14, one to three weeks after the median last frost.

How much rain and snow does 50108 get?

About 38 inches of precipitation a year and 27 inches of snowfall (NOAA 1991–2020 normals, Beaconsfield station).

How hot do summers get in Grand River, IA?

The average high peaks at 84 °F in July, with about 13 days a year at 90 °F or more.

What kind of soil does 50108 have?

The USDA soil survey maps Mystic at the center of ZIP 50108: clay loam, somewhat poorly drained, pH about 5.9 (moderately acidic).

Did spring come early in Grand River, IA in 2026?

Spring leaf-out near 50108 came on Mar 11 in 2026, 20 days earlier than the 1991–2020 average (Mar 31), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Grand River, IA?

Long-day onions: the longest day near 50108 is 15 h 06 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).