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

Planting zone for 55724 — Cotton, MN

ZIP code 55724 (Cotton, St. Louis County) is in USDA zone 3b: the coldest winter night averages −35 to −30 °F. The median last spring frost is May 27 and the first fall frost September 20.

Where ZIP 55724 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.

Zone3b−35 to −30 °F

Coldest night−37.2 to −34.4 °C

Last frostMay 27

First frostSep 20

2012 zone3a

Was 3a 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 3b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Cotton, 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 Cotton, MN

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 27median — 50% chance of a later frost

Safe for tender plantsJune 11only 10% chance of frost after

First fall frostSeptember 20median — 10% chance by Sep 4

Growing season115 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 14 and returns around October 1.

From the NOAA station Cotton, MN — 4 miles away, elevation 1,322 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 55724

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 15 – Apr 29

SpinachSow outdoors · Apr 15 – May 6

Broccoli, cabbageStart indoors · Mar 18 – Apr 1

Broccoli, cabbageTransplant · May 6 – May 20

Onion setsPlant outdoors · Apr 29 – May 13

PotatoesPlant outdoors · May 6 – May 20

LettuceSow outdoors · Apr 29 – May 13

Carrots, beetsSow outdoors · May 6 – May 20

TomatoesStart indoors · Apr 1 – Apr 15

TomatoesTransplant · Jun 3 – Jun 17

Peppers, eggplantStart indoors · Mar 18 – Apr 1

Peppers, eggplantTransplant · Jun 10 – Jun 24

BeansSow outdoors · Jun 3 – Jun 17

Sweet cornSow outdoors · Jun 3 – Jun 17

Cucumbers, squashSow outdoors · Jun 3 – Jun 17

Fall lettuce, spinachSow outdoors · Jul 26 – Aug 9

GarlicPlant cloves · Sep 6 – Oct 11

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 27) and first fall frost (Sep 20) 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 55724 came on Apr 30 — about the same time as the 1991–2020 average (Apr 28).

average
Apr 282026
Apr 30

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 3b in Minnesota

287 plants native to the lower 48 states, recorded in Minnesota, and rated by the USDA to survive −35 °F or colder — the bottom of zone 3b. 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 Cotton, MN.

Soil in Cotton, MN

The soil mapped at the center of ZIP 55724 is Grayling — loamy sand, excessively drained.

TextureLoamy sanddrains and warms fast; dries out and needs more feeding

pH5.6moderately acidic; most vegetables like 6.0–7.0

DrainageExcessively drainednatural drainage class

Organic matter3%moderate

Hydrologic groupAwater soaks in fast

Farmland classNot prime farmlandUSDA classification

Map unit: Grayling-Grytal-Cromwell complex, pitted, 0 to 8 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 55724; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Cotton, MN

Summer high78 °Faverage high, July

Winter low−5 °Faverage low, January

Hot days3days a year at 90 °F or more

Freezing nights207nights a year at 32 °F or less

Growing degree days1,559base 50 °F — the season’s usable heat

Longest day15 h 55 mindaylight on June 21

Shortest day8 h 29 mindaylight on December 21

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

Precipitation29.2 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: Cotton, MN (4 mi away); precipitation: Cotton, MN (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

Meadowlands, MN · 18 mi

557794a

Saginaw, MN · 18 mi

Minnesota planting zones →

Questions about 55724

What planting zone is ZIP code 55724?

ZIP code 55724 (Cotton, MN) is in USDA hardiness zone 3b on the 2023 map: the coldest night of an average winter reaches −35 to −30 °F (−37.2 to −34.4 °C).

When is the last frost in Cotton, MN?

The median last spring frost (32 °F) near 55724 is May 27; after June 11 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Cotton station.

When is the first frost in Cotton, MN?

The median first fall frost near 55724 is September 20, giving a median frost-free growing season of 115 days.

When should I plant tomatoes in 55724?

Start tomato seeds indoors around Apr 1 – Apr 15 and set transplants outside around Jun 3 – Jun 17, one to three weeks after the median last frost.

How much rain and snow does 55724 get?

About 29.2 inches of precipitation a year (NOAA 1991–2020 normals, Cotton station).

How hot do summers get in Cotton, MN?

The average high peaks at 78 °F in July, with about 3 days a year at 90 °F or more.

What kind of soil does 55724 have?

The USDA soil survey maps Grayling at the center of ZIP 55724: loamy sand, excessively drained, pH about 5.6 (moderately acidic).

Did spring come early in Cotton, MN in 2026?

Spring leaf-out near 55724 came on Apr 30 in 2026, about the same as the 1991–2020 average (Apr 28), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Cotton, MN?

Long-day onions: the longest day near 55724 is 15 h 55 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 55724 change?

Yes. The 2012 USDA map put 55724 in zone 3a; the 2023 map puts it in zone 3b. The newer map uses 1991–2020 data and more weather stations.