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

Planting zone for 55721 — Cohasset, MN

ZIP code 55721 (Cohasset, Itasca County) is in USDA zone 4a: the coldest winter night averages −30 to −25 °F. The median last spring frost is May 16 and the first fall frost October 1.

Where ZIP 55721 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.

Zone4a−30 to −25 °F

Coldest night−34.4 to −31.7 °C

Last frostMay 16

First frostOct 1

2012 zone3b

Was 3b on the 2012 map — half a zone warmer now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 4a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Cohasset, 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 Cohasset, MN

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 16median — 50% chance of a later frost

Safe for tender plantsMay 31only 10% chance of frost after

First fall frostOctober 1median — 10% chance by Sep 18

Growing season138 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 3 and returns around October 10.

From the NOAA station Pokegama Dam, MN — 5 miles away, elevation 1,280 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 55721

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 4 – Apr 18

SpinachSow outdoors · Apr 4 – Apr 25

Broccoli, cabbageStart indoors · Mar 7 – Mar 21

Broccoli, cabbageTransplant · Apr 25 – May 9

Onion setsPlant outdoors · Apr 18 – May 2

PotatoesPlant outdoors · Apr 25 – May 9

LettuceSow outdoors · Apr 18 – May 2

Carrots, beetsSow outdoors · Apr 25 – May 9

TomatoesStart indoors · Mar 21 – Apr 4

TomatoesTransplant · May 23 – Jun 6

Peppers, eggplantStart indoors · Mar 7 – Mar 21

Peppers, eggplantTransplant · May 30 – Jun 13

BeansSow outdoors · May 23 – Jun 6

Sweet cornSow outdoors · May 23 – Jun 6

Cucumbers, squashSow outdoors · May 23 – Jun 6

Fall lettuce, spinachSow outdoors · Aug 6 – Aug 20

GarlicPlant cloves · Sep 17 – Oct 22

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 16) and first fall frost (Oct 1) 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 55721 came on Apr 22 — 3 days earlier than the 1991–2020 average (Apr 25).

average
Apr 252026
Apr 22

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 4a in Minnesota

445 plants native to the lower 48 states, recorded in Minnesota, and rated by the USDA to survive −30 °F or colder — the bottom of zone 4a. 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 Cohasset, MN.

Soil in Cohasset, MN

The soil mapped at the center of ZIP 55721 is Itasca — silt loam, well drained.

TextureSilt loama good balance for most vegetables

pH5.8moderately acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter1.75%low — add compost

Hydrologic groupBwater soaks in moderately

Farmland classNot prime farmlandUSDA classification

Map unit: Itasca-Goodland silt loams, 12 to 25 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 55721; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Cohasset, MN

Summer high78 °Faverage high, July

Winter low−3 °Faverage low, January

Hot days2days a year at 90 °F or more

Freezing nights185nights a year at 32 °F or less

Growing degree days1,865base 50 °F — the season’s usable heat

Longest day15 h 56 mindaylight on June 21

Shortest day8 h 28 mindaylight on December 21

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

Precipitation27.7 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: Pokegama Dam, MN (5 mi away); precipitation: Pokegama Dam, MN (5 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

2 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

557304a

Grand Rapids, MN · 7 mi

557454a

Grand Rapids, MN · 7 mi

557444a

Grand Rapids, MN · 8 mi

557224a

Coleraine, MN · 12 mi

566363b

Deer River, MN · 14 mi

557864a

Taconite, MN · 16 mi

557484a

Hill City, MN · 16 mi

557093b

Bovey, MN · 19 mi

Minnesota planting zones →

Questions about 55721

What planting zone is ZIP code 55721?

ZIP code 55721 (Cohasset, MN) is in USDA hardiness zone 4a on the 2023 map: the coldest night of an average winter reaches −30 to −25 °F (−34.4 to −31.7 °C).

When is the last frost in Cohasset, MN?

The median last spring frost (32 °F) near 55721 is May 16; after May 31 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Pokegama Dam station.

When is the first frost in Cohasset, MN?

The median first fall frost near 55721 is October 1, giving a median frost-free growing season of 138 days.

When should I plant tomatoes in 55721?

Start tomato seeds indoors around Mar 21 – Apr 4 and set transplants outside around May 23 – Jun 6, one to three weeks after the median last frost.

How much rain and snow does 55721 get?

About 27.7 inches of precipitation a year (NOAA 1991–2020 normals, Pokegama Dam station).

How hot do summers get in Cohasset, MN?

The average high peaks at 78 °F in July, with about 2 days a year at 90 °F or more.

What kind of soil does 55721 have?

The USDA soil survey maps Itasca at the center of ZIP 55721: silt loam, well drained, pH about 5.8 (moderately acidic).

Did spring come early in Cohasset, MN in 2026?

Spring leaf-out near 55721 came on Apr 22 in 2026, 3 days earlier than the 1991–2020 average (Apr 25), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Cohasset, MN?

Long-day onions: the longest day near 55721 is 15 h 56 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 55721 change?

Yes. The 2012 USDA map put 55721 in zone 3b; the 2023 map puts it in zone 4a. The newer map uses 1991–2020 data and more weather stations.