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

Planting zone for 50531 — Dolliver, IA

ZIP code 50531 (Dolliver, Emmet County) is in USDA zone 5a: the coldest winter night averages −20 to −15 °F. The median last spring frost is May 2 and the first fall frost September 30.

Where ZIP 50531 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 frostMay 2
First frostSep 30
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 Dolliver, 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 Dolliver, IA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 2median — 50% chance of a later frost
Safe for tender plantsMay 14only 10% chance of frost after
First fall frostSeptember 30median — 10% chance by Sep 17
Growing season150 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 24 and returns around October 10.

From the NOAA station Estherville Municipal Airport, IA — 7 miles away, elevation 1,316 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 50531

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 21 – Apr 4
SpinachSow outdoors · Mar 21 – Apr 11
Broccoli, cabbageStart indoors · Feb 21 – Mar 7
Broccoli, cabbageTransplant · Apr 11 – Apr 25
Onion setsPlant outdoors · Apr 4 – Apr 18
PotatoesPlant outdoors · Apr 11 – Apr 25
LettuceSow outdoors · Apr 4 – Apr 18
Carrots, beetsSow outdoors · Apr 11 – Apr 25
TomatoesStart indoors · Mar 7 – Mar 21
TomatoesTransplant · May 9 – May 23
Peppers, eggplantStart indoors · Feb 21 – Mar 7
Peppers, eggplantTransplant · May 16 – May 30
BeansSow outdoors · May 9 – May 23
Sweet cornSow outdoors · May 9 – May 23
Cucumbers, squashSow outdoors · May 9 – May 23
Fall lettuce, spinachSow outdoors · Aug 5 – Aug 19
GarlicPlant cloves · Sep 16 – Oct 21
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 2) and first fall frost (Sep 30) 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 50531 came on Mar 28 — 17 days earlier than the 1991–2020 average (Apr 14).

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 Dolliver, IA.

Soil in Dolliver, IA

The soil mapped at the center of ZIP 50531 is Clarion — loam, moderately well drained.

TextureLoama good balance for most vegetables
pH6.2slightly acidic; most vegetables like 6.0–7.0
DrainageModerately well drainednatural drainage class
Organic matter3.5%moderate
Hydrologic groupCwater soaks in slowly
Farmland classprime farmlandUSDA classification

Map unit: Clarion-Swanlake complex, 2 to 6 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 50531; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Dolliver, IA

Summer high81 °Faverage high, July
Winter low7 °Faverage low, January
Hot days10days a year at 90 °F or more
Freezing nights161nights a year at 32 °F or less
Growing degree days2,493base 50 °F — the season’s usable heat
Longest day15 h 25 mindaylight on June 21
Shortest day8 h 57 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation29.3 inper year, rain and melted snow

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 23 °F, low 7 °F 23°7° JanFebruary: average high 28 °F, low 11 °F 28°11° FebMarch: average high 41 °F, low 23 °F 41°23° MarApril: average high 56 °F, low 34 °F 56°34° AprMay: average high 69 °F, low 46 °F 69°46° MayJune: average high 79 °F, low 57 °F 79°57° JunJuly: average high 81 °F, low 60 °F 81°60° JulAugust: average high 79 °F, low 57 °F 79°57° AugSeptember: average high 73 °F, low 49 °F 73°49° SepOctober: average high 59 °F, low 36 °F 59°36° OctNovember: average high 42 °F, low 23 °F 42°23° NovDecember: average high 28 °F, low 12 °F 28°12° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 0.56 in precipitation 0.6 JanFebruary: 0.46 in precipitation 0.5 FebMarch: 1.45 in precipitation 1.4 MarApril: 3.13 in precipitation 3.1 AprMay: 4.50 in precipitation 4.5 MayJune: 4.57 in precipitation 4.6 JunJuly: 3.76 in precipitation 3.8 JulAugust: 3.31 in precipitation 3.3 AugSeptember: 3.14 in precipitation 3.1 SepOctober: 2.47 in precipitation 2.5 OctNovember: 1.37 in precipitation 1.4 NovDecember: 0.54 in precipitation 0.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Estherville Municipal Airport, IA (7 mi away); precipitation: Estherville Municipal Airport, IA (7 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 5a.

561215a
Ceylon, MN · 6 mi
505145a
Armstrong, IA · 7 mi
561275a
Dunnell, MN · 10 mi
513345a
Estherville, IA · 10 mi
505785a
Ringsted, IA · 11 mi
513655a
Wallingford, IA · 12 mi
560315a
Fairmont, MN · 14 mi
561815a
Welcome, MN · 15 mi

Iowa planting zones →

Questions about 50531

What planting zone is ZIP code 50531?

ZIP code 50531 (Dolliver, 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 Dolliver, IA?

The median last spring frost (32 °F) near 50531 is May 2; after May 14 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Estherville Municipal Airport station.

When is the first frost in Dolliver, IA?

The median first fall frost near 50531 is September 30, giving a median frost-free growing season of 150 days.

When should I plant tomatoes in 50531?

Start tomato seeds indoors around Mar 7 – Mar 21 and set transplants outside around May 9 – May 23, one to three weeks after the median last frost.

How much rain and snow does 50531 get?

About 29.3 inches of precipitation a year (NOAA 1991–2020 normals, Estherville Municipal Airport station).

How hot do summers get in Dolliver, IA?

The average high peaks at 81 °F in July, with about 10 days a year at 90 °F or more.

What kind of soil does 50531 have?

The USDA soil survey maps Clarion at the center of ZIP 50531: loam, moderately well drained, pH about 6.2 (slightly acidic).

Did spring come early in Dolliver, IA in 2026?

Spring leaf-out near 50531 came on Mar 28 in 2026, 17 days earlier than the 1991–2020 average (Apr 14), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Dolliver, IA?

Long-day onions: the longest day near 50531 is 15 h 25 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).