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

Planting zone for 56226 — Clontarf, MN

ZIP code 56226 (Clontarf, Swift County) is in USDA zone 4b: the coldest winter night averages −25 to −20 °F. The median last spring frost is May 4 and the first fall frost October 3.

Where ZIP 56226 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.

Zone4b−25 to −20 °F

Coldest night−31.7 to −28.9 °C

Last frostMay 4

First frostOct 3

2012 zone4b

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 4b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Clontarf, MN…

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 Clontarf, MN

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 4median — 50% chance of a later frost

Safe for tender plantsMay 17only 10% chance of frost after

First fall frostOctober 3median — 10% chance by Sep 21

Growing season151 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 26 and returns around October 12.

From the NOAA station Benson, MN — 7 miles away, elevation 1,030 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 56226

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 23 – Apr 6

SpinachSow outdoors · Mar 23 – Apr 13

Broccoli, cabbageStart indoors · Feb 23 – Mar 9

Broccoli, cabbageTransplant · Apr 13 – Apr 27

Onion setsPlant outdoors · Apr 6 – Apr 20

PotatoesPlant outdoors · Apr 13 – Apr 27

LettuceSow outdoors · Apr 6 – Apr 20

Carrots, beetsSow outdoors · Apr 13 – Apr 27

TomatoesStart indoors · Mar 9 – Mar 23

TomatoesTransplant · May 11 – May 25

Peppers, eggplantStart indoors · Feb 23 – Mar 9

Peppers, eggplantTransplant · May 18 – Jun 1

BeansSow outdoors · May 11 – May 25

Sweet cornSow outdoors · May 11 – May 25

Cucumbers, squashSow outdoors · May 11 – May 25

Fall lettuce, spinachSow outdoors · Aug 8 – Aug 22

GarlicPlant cloves · Sep 19 – Oct 24

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 4) and first fall frost (Oct 3) 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 56226 came on Apr 18 — about the same time as the 1991–2020 average (Apr 19).

average
Apr 192026
Apr 18

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 4b in Minnesota

497 plants native to the lower 48 states, recorded in Minnesota, and rated by the USDA to survive −25 °F or colder — the bottom of zone 4b. 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 Clontarf, MN.

Soil in Clontarf, MN

The soil mapped at the center of ZIP 56226 is Arveson — sandy loam, poorly drained.

TextureSandy loamdrains and warms fast; dries out and needs more feeding

pH7.9alkaline; most vegetables like 6.0–7.0

DrainagePoorly drainedconsider raised beds

Organic matter6.5%high

Hydrologic groupA/Ddrains fast once dried out; wet otherwise

Farmland classPrime farmland if drainedUSDA classification

Map unit: Arveson sandy loam, 0 to 2 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 56226; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Clontarf, MN

Summer high83 °Faverage high, July

Winter low1 °Faverage low, January

Hot days12days a year at 90 °F or more

Freezing nights168nights a year at 32 °F or less

Growing degree days2,620base 50 °F — the season’s usable heat

Longest day15 h 40 mindaylight on June 21

Shortest day8 h 43 mindaylight on December 21

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

Precipitation28.1 inper year, rain and melted snow

Snowfall43 inper year; 100 days with snow on the ground

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

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

Nearby ZIP codes

All 8 nearest ZIP codes share zone 4b.

Minnesota planting zones →

Questions about 56226

What planting zone is ZIP code 56226?

ZIP code 56226 (Clontarf, MN) is in USDA hardiness zone 4b on the 2023 map: the coldest night of an average winter reaches −25 to −20 °F (−31.7 to −28.9 °C).

When is the last frost in Clontarf, MN?

The median last spring frost (32 °F) near 56226 is May 4; after May 17 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Benson station.

When is the first frost in Clontarf, MN?

The median first fall frost near 56226 is October 3, giving a median frost-free growing season of 151 days.

When should I plant tomatoes in 56226?

Start tomato seeds indoors around Mar 9 – Mar 23 and set transplants outside around May 11 – May 25, one to three weeks after the median last frost.

How much rain and snow does 56226 get?

About 28.1 inches of precipitation a year and 43 inches of snowfall (NOAA 1991–2020 normals, Benson station).

How hot do summers get in Clontarf, MN?

The average high peaks at 83 °F in July, with about 12 days a year at 90 °F or more.

What kind of soil does 56226 have?

The USDA soil survey maps Arveson at the center of ZIP 56226: sandy loam, poorly drained, pH about 7.9 (alkaline).

Did spring come early in Clontarf, MN in 2026?

Spring leaf-out near 56226 came on Apr 18 in 2026, about the same as the 1991–2020 average (Apr 19), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Clontarf, MN?

Long-day onions: the longest day near 56226 is 15 h 40 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).