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

Planting zone for Duluth, MN

Duluth, MN is in USDA zones 4a to 5a across its 13 ZIP codes. The median last spring frost is May 14 and the first fall frost October 12.

Duluth on the zone map

Outlined: its 11 ZIP code areas · 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.

Zones4a–5a−30 to −15 °F
ZIP codes13
Last frostMay 14
First frostOct 12
Growing season149 days

4a 1 ZIP   4b 10 ZIPs   5a 2 ZIPs

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 14median — 50% chance of a later frost
Safe for tender plantsJune 1only 10% chance of frost after
First fall frostOctober 12median — 10% chance by Sep 25
Growing season149 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 29 and returns around October 25.

From the NOAA station Duluth Harbor Stn, MN, elevation 610 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 Duluth

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 2 – Apr 16
SpinachSow outdoors · Apr 2 – Apr 23
Broccoli, cabbageStart indoors · Mar 5 – Mar 19
Broccoli, cabbageTransplant · Apr 23 – May 7
Onion setsPlant outdoors · Apr 16 – Apr 30
PotatoesPlant outdoors · Apr 23 – May 7
LettuceSow outdoors · Apr 16 – Apr 30
Carrots, beetsSow outdoors · Apr 23 – May 7
TomatoesStart indoors · Mar 19 – Apr 2
TomatoesTransplant · May 21 – Jun 4
Peppers, eggplantStart indoors · Mar 5 – Mar 19
Peppers, eggplantTransplant · May 28 – Jun 11
BeansSow outdoors · May 21 – Jun 4
Sweet cornSow outdoors · May 21 – Jun 4
Cucumbers, squashSow outdoors · May 21 – Jun 4
Fall lettuce, spinachSow outdoors · Aug 17 – Aug 31
GarlicPlant cloves · Sep 28 – Nov 2
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 14) and first fall frost (Oct 12) 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 55805 came on May 2 — about the same time as the 1991–2020 average (May 1).

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.

Trees 45

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican beech80 ft · blooms mid spring · low shade tolerance · to −44 °FAmerican elm120 ft · blooms early spring · medium shade tolerance · to −46 °Farborvitae50 ft · blooms mid spring · medium shade tolerance · to −33 °Fbalsam fir60 ft · blooms mid summer · low shade tolerance · to −43 °Fbalsam poplar80 ft · blooms late spring · high shade tolerance · to −79 °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 173

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine bistort1 ft · blooms mid spring · high 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 °F

Grasses 140

alkali cordgrass3 ft · blooms late summer · high shade tolerance · to −38 °Farctic brome3 ft · blooms early summer · low shade tolerance · to −33 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °Fbasin wildrye5 ft · blooms early spring · high shade tolerance · to −43 °Fbeaked sedge4 ft · blooms late spring · low shade tolerance · to −38 °FBebb's sedge3 ft · blooms late spring · low shade tolerance · to −38 °F

Vines 3

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Friverbank grape45 ft · blooms late spring · medium 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 Duluth, MN.

Soil in Duluth, MN

The soil mapped at the center of ZIP 55805 is Mesaba — gravelly sandy loam, well drained. Much of the area is built over (urban land); this is the natural soil underneath.

TextureGravelly sandy loamdrains and warms fast; dries out and needs more feeding
pH5.1strongly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter5%high
Hydrologic groupBwater soaks in moderately
Farmland classNot prime farmlandUSDA classification

Map unit: Urban land-Mesaba-Rock outcrop complex, 1 to 18 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 55805; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Duluth, MN

Summer high75 °Faverage high, July
Winter low4 °Faverage low, January
Hot days2days a year at 90 °F or more
Freezing nights166nights a year at 32 °F or less
Growing degree days1,664base 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)
Precipitation31.1 inper year, rain and melted snow

Average high and low, by month

−10°0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 21 °F, low 4 °F 21°4° JanFebruary: average high 26 °F, low 8 °F 26°8° FebMarch: average high 35 °F, low 19 °F 35°19° MarApril: average high 45 °F, low 31 °F 45°31° AprMay: average high 56 °F, low 41 °F 56°41° MayJune: average high 66 °F, low 49 °F 66°49° JunJuly: average high 75 °F, low 58 °F 75°58° JulAugust: average high 74 °F, low 60 °F 74°60° AugSeptember: average high 66 °F, low 51 °F 66°51° SepOctober: average high 52 °F, low 39 °F 52°39° OctNovember: average high 39 °F, low 26 °F 39°26° NovDecember: average high 27 °F, low 13 °F 27°13° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 1.02 in precipitation 1.0 JanFebruary: 0.91 in precipitation 0.9 FebMarch: 1.49 in precipitation 1.5 MarApril: 2.58 in precipitation 2.6 AprMay: 3.46 in precipitation 3.5 MayJune: 4.41 in precipitation 4.4 JunJuly: 4.11 in precipitation 4.1 JulAugust: 3.42 in precipitation 3.4 AugSeptember: 3.46 in precipitation 3.5 SepOctober: 3.03 in precipitation 3.0 OctNovember: 1.71 in precipitation 1.7 NovDecember: 1.48 in precipitation 1.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Duluth Harbor Stn, MN (2 mi away); precipitation: Duluth 3.0 Ne, MN (2 mi away). Daylight is calculated from latitude.

ZIP codes in Duluth

558025a
−20 to −15 °F
558034a
−30 to −25 °F
558044b
−25 to −20 °F
558054b
−25 to −20 °F
558064b
−25 to −20 °F
558074b
−25 to −20 °F
558084b
−25 to −20 °F
558104b
−25 to −20 °F
558114b
−25 to −20 °F
558124b
−25 to −20 °F
558144b
−25 to −20 °F
558154b
−25 to −20 °F
558165a
−20 to −15 °F

Minnesota planting zones →

Questions about Duluth

What planting zone is Duluth, MN?

Duluth, MN is in USDA hardiness zones 4a to 5a on the 2023 map (4a: −30 to −25 °F; 4b: −25 to −20 °F; 5a: −20 to −15 °F).

When is the last frost in Duluth, MN?

The median last spring frost is May 14 and the median first fall frost is October 12 (NOAA 1991–2020 normals, Duluth Harbor Stn station).

When can I plant a garden in Duluth, MN?

Cool-season crops like peas and spinach go in around Apr 2 – Apr 23; tomatoes, peppers, beans and squash after about May 21, once frost risk has passed.

What kind of onions grow in Duluth, MN?

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

How much rain and snow does Duluth, MN get?

About 31.1 inches of precipitation a year (NOAA 1991–2020 normals).