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

Planting zone for 50657 — Morrison, IA

ZIP code 50657 (Morrison, Grundy County) is in USDA zone 5a: the coldest winter night averages −20 to −15 °F. The median last spring frost is April 29 and the first fall frost October 9.

Where ZIP 50657 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 29
First frostOct 9
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 Morrison, 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 Morrison, IA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 29median — 50% chance of a later frost
Safe for tender plantsMay 12only 10% chance of frost after
First fall frostOctober 9median — 10% chance by Sep 25
Growing season160 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 19 and returns around October 18.

From the NOAA station Grundy Center, IA — 4 miles away, elevation 984 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 50657

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 18 – Apr 1
SpinachSow outdoors · Mar 18 – Apr 8
Broccoli, cabbageStart indoors · Feb 18 – Mar 4
Broccoli, cabbageTransplant · Apr 8 – Apr 22
Onion setsPlant outdoors · Apr 1 – Apr 15
PotatoesPlant outdoors · Apr 8 – Apr 22
LettuceSow outdoors · Apr 1 – Apr 15
Carrots, beetsSow outdoors · Apr 8 – Apr 22
TomatoesStart indoors · Mar 4 – Mar 18
TomatoesTransplant · May 6 – May 20
Peppers, eggplantStart indoors · Feb 18 – Mar 4
Peppers, eggplantTransplant · May 13 – May 27
BeansSow outdoors · May 6 – May 20
Sweet cornSow outdoors · May 6 – May 20
Cucumbers, squashSow outdoors · May 6 – May 20
Fall lettuce, spinachSow outdoors · Aug 14 – Aug 28
GarlicPlant cloves · Sep 25 – Oct 30
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 29) and first fall frost (Oct 9) 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 50657 came on Mar 25 — 16 days earlier than the 1991–2020 average (Apr 10).

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.

Trees 46

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 185

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 133

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 Morrison, IA.

Soil in Morrison, IA

The soil mapped at the center of ZIP 50657 is Wiota — silt loam, moderately well drained.

TextureSilt loama good balance for most vegetables
pH5.7moderately acidic; most vegetables like 6.0–7.0
DrainageModerately well drainednatural drainage class
Organic matter4%moderate
Hydrologic groupCwater soaks in slowly
Farmland classprime farmlandUSDA classification

Map unit: Wiota silt loam, 0 to 2 percent slopes, rarely flooded.

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 50657; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Morrison, IA

Summer high83 °Faverage high, July
Winter low9 °Faverage low, January
Hot days11days a year at 90 °F or more
Freezing nights155nights a year at 32 °F or less
Growing degree days2,866base 50 °F — the season’s usable heat
Longest day15 h 17 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)
Precipitation36.8 inper year, rain and melted snow
Snowfall32 inper year; 70 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 26 °F, low 9 °F 26°9° JanFebruary: average high 31 °F, low 13 °F 31°13° FebMarch: average high 44 °F, low 24 °F 44°24° MarApril: average high 59 °F, low 36 °F 59°36° AprMay: average high 70 °F, low 48 °F 70°48° MayJune: average high 80 °F, low 60 °F 80°60° JunJuly: average high 83 °F, low 62 °F 83°62° JulAugust: average high 81 °F, low 60 °F 81°60° AugSeptember: average high 75 °F, low 51 °F 75°51° SepOctober: average high 62 °F, low 38 °F 62°38° OctNovember: average high 45 °F, low 26 °F 45°26° NovDecember: average high 32 °F, low 15 °F 32°15° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″6″January: 0.83 in precipitation, 9.2 in snowfall 0.8❄9 JanFebruary: 0.98 in precipitation, 5.9 in snowfall 1.0❄6 FebMarch: 1.88 in precipitation, 3.9 in snowfall 1.9❄4 MarApril: 3.88 in precipitation, 1.4 in snowfall 3.9❄1 AprMay: 4.89 in precipitation 4.9 MayJune: 5.65 in precipitation 5.7 JunJuly: 4.43 in precipitation 4.4 JulAugust: 4.80 in precipitation 4.8 AugSeptember: 3.28 in precipitation 3.3 SepOctober: 2.88 in precipitation, 0.3 in snowfall 2.9 OctNovember: 1.88 in precipitation, 2.1 in snowfall 1.9❄2 NovDecember: 1.44 in precipitation, 9.5 in snowfall 1.4❄10 Dec

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

Nearby ZIP codes

All 8 nearest ZIP codes share zone 5a.

506695a
Reinbeck, IA · 3 mi
506525a
Lincoln, IA · 6 mi
506385a
Grundy Center, IA · 6 mi
506245a
Dike, IA · 9 mi
506425a
Holland, IA · 10 mi
506355a
Gladbrook, IA · 10 mi
506095a
Beaman, IA · 11 mi
506435a
Hudson, IA · 11 mi

Iowa planting zones →

Questions about 50657

What planting zone is ZIP code 50657?

ZIP code 50657 (Morrison, 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 Morrison, IA?

The median last spring frost (32 °F) near 50657 is April 29; after May 12 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Grundy Center station.

When is the first frost in Morrison, IA?

The median first fall frost near 50657 is October 9, giving a median frost-free growing season of 160 days.

When should I plant tomatoes in 50657?

Start tomato seeds indoors around Mar 4 – Mar 18 and set transplants outside around May 6 – May 20, one to three weeks after the median last frost.

How much rain and snow does 50657 get?

About 36.8 inches of precipitation a year and 32 inches of snowfall (NOAA 1991–2020 normals, Grundy Center station).

How hot do summers get in Morrison, IA?

The average high peaks at 83 °F in July, with about 11 days a year at 90 °F or more.

What kind of soil does 50657 have?

The USDA soil survey maps Wiota at the center of ZIP 50657: silt loam, moderately well drained, pH about 5.7 (moderately acidic).

Did spring come early in Morrison, IA in 2026?

Spring leaf-out near 50657 came on Mar 25 in 2026, 16 days earlier than the 1991–2020 average (Apr 10), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Morrison, IA?

Long-day onions: the longest day near 50657 is 15 h 17 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).