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

Planting zone for 55814 — Duluth, MN

ZIP code 55814 (Duluth, St. Louis County) is in USDA zone 4b: the coldest winter night averages −25 to −20 °F. The median last spring frost is May 13 and the first fall frost October 1.

Where ZIP 55814 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 13

First frostOct 1

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 Duluth, 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 Duluth, MN

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 13median — 50% chance of a later frost

Safe for tender plantsMay 29only 10% chance of frost after

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

Growing season140 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 30 and returns around October 13.

From the NOAA station Duluth, MN — within 1 mile, elevation 1,427 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 55814

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 1 – Apr 15

SpinachSow outdoors · Apr 1 – Apr 22

Broccoli, cabbageStart indoors · Mar 4 – Mar 18

Broccoli, cabbageTransplant · Apr 22 – May 6

Onion setsPlant outdoors · Apr 15 – Apr 29

PotatoesPlant outdoors · Apr 22 – May 6

LettuceSow outdoors · Apr 15 – Apr 29

Carrots, beetsSow outdoors · Apr 22 – May 6

TomatoesStart indoors · Mar 18 – Apr 1

TomatoesTransplant · May 20 – Jun 3

Peppers, eggplantStart indoors · Mar 4 – Mar 18

Peppers, eggplantTransplant · May 27 – Jun 10

BeansSow outdoors · May 20 – Jun 3

Sweet cornSow outdoors · May 20 – Jun 3

Cucumbers, squashSow outdoors · May 20 – Jun 3

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 13) 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 55814 came on May 2 — 4 days later than the 1991–2020 average (Apr 28).

average
Apr 282026
May 2

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).

Soil in Duluth, MN

The soil mapped at the center of ZIP 55814 is Canosia — loam, poorly drained. Much of the area is built over (urban land); this is the natural soil underneath.

TextureLoama good balance for most vegetables

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

DrainagePoorly drainedconsider raised beds

Organic matter8%high

Hydrologic groupDwater soaks in very slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Urban land-Normanna-Canosia complex, 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 55814; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Duluth, MN

Summer high78 °Faverage high, July

Winter low2 °Faverage low, January

Hot days2days a year at 90 °F or more

Freezing nights177nights a year at 32 °F or less

Growing degree days1,789base 50 °F — the season’s usable heat

Longest day15 h 52 mindaylight on June 21

Shortest day8 h 32 mindaylight on December 21

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

Precipitation31.2 inper year, rain and melted snow

Snowfall90 inper year; 137 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: Duluth, MN (within 1 mile); precipitation: Duluth, MN (within 1 mile). Daylight is calculated from latitude.

Nearby ZIP codes

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

All 13 ZIP codes in Duluth → · Minnesota planting zones →

Questions about 55814

What planting zone is ZIP code 55814?

ZIP code 55814 (Duluth, 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 Duluth, MN?

The median last spring frost (32 °F) near 55814 is May 13; after May 29 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Duluth station.

When is the first frost in Duluth, MN?

The median first fall frost near 55814 is October 1, giving a median frost-free growing season of 140 days.

When should I plant tomatoes in 55814?

Start tomato seeds indoors around Mar 18 – Apr 1 and set transplants outside around May 20 – Jun 3, one to three weeks after the median last frost.

How much rain and snow does 55814 get?

About 31.2 inches of precipitation a year and 90 inches of snowfall (NOAA 1991–2020 normals, Duluth station).

How hot do summers get in Duluth, 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 55814 have?

The USDA soil survey maps Canosia at the center of ZIP 55814: loam, poorly drained, pH about 5.6 (moderately acidic).

Did spring come early in Duluth, MN in 2026?

Spring leaf-out near 55814 came on May 2 in 2026, 4 days later than the 1991–2020 average (Apr 28), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Duluth, MN?

Long-day onions: the longest day near 55814 is 15 h 52 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).