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

Planting zone for 55707 — Barnum, MN

ZIP code 55707 (Barnum, Carlton County) is in USDA zone 4a: the coldest winter night averages −30 to −25 °F. The median last spring frost is May 12 and the first fall frost October 2.

Where ZIP 55707 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 12
First frostOct 2
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 Barnum, 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 Barnum, MN

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 12median — 50% chance of a later frost
Safe for tender plantsMay 26only 10% chance of frost after
First fall frostOctober 2median — 10% chance by Sep 20
Growing season144 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 30 and returns around October 14.

From the NOAA station Moose Lake 1 Sse, MN — 10 miles away, elevation 1,109 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 55707

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 31 – Apr 14
SpinachSow outdoors · Mar 31 – Apr 21
Broccoli, cabbageStart indoors · Mar 3 – Mar 17
Broccoli, cabbageTransplant · Apr 21 – May 5
Onion setsPlant outdoors · Apr 14 – Apr 28
PotatoesPlant outdoors · Apr 21 – May 5
LettuceSow outdoors · Apr 14 – Apr 28
Carrots, beetsSow outdoors · Apr 21 – May 5
TomatoesStart indoors · Mar 17 – Mar 31
TomatoesTransplant · May 19 – Jun 2
Peppers, eggplantStart indoors · Mar 3 – Mar 17
Peppers, eggplantTransplant · May 26 – Jun 9
BeansSow outdoors · May 19 – Jun 2
Sweet cornSow outdoors · May 19 – Jun 2
Cucumbers, squashSow outdoors · May 19 – Jun 2
Fall lettuce, spinachSow outdoors · Aug 7 – Aug 21
GarlicPlant cloves · Sep 18 – Oct 23
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 12) and first fall frost (Oct 2) 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 55707 came on Apr 30 — 5 days later than the 1991–2020 average (Apr 25).

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 Barnum, MN

The soil mapped at the center of ZIP 55707 is Blackhoof — muck, very poorly drained.

TextureMucktop layer
pH5.8moderately acidic; most vegetables like 6.0–7.0
DrainageVery poorly drainedconsider raised beds
Organic matter65%high
Hydrologic groupC/Dslow when drained; wet otherwise
Farmland classNot prime farmlandUSDA classification

Map unit: Blackhoof and Mahtowa soils.

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 55707; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Barnum, MN

Summer high80 °Faverage high, July
Winter low1 °Faverage low, January
Hot days5days a year at 90 °F or more
Freezing nights175nights a year at 32 °F or less
Growing degree days2,012base 50 °F — the season’s usable heat
Longest day15 h 50 mindaylight on June 21
Shortest day8 h 34 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation31.5 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 20 °F, low 1 °F 20°1° JanFebruary: average high 25 °F, low 4 °F 25°4° FebMarch: average high 38 °F, low 17 °F 38°17° MarApril: average high 52 °F, low 30 °F 52°30° AprMay: average high 66 °F, low 41 °F 66°41° MayJune: average high 75 °F, low 51 °F 75°51° JunJuly: average high 80 °F, low 57 °F 80°57° JulAugust: average high 78 °F, low 56 °F 78°56° AugSeptember: average high 69 °F, low 48 °F 69°48° SepOctober: average high 54 °F, low 36 °F 54°36° OctNovember: average high 38 °F, low 23 °F 38°23° NovDecember: average high 25 °F, low 9 °F 25°9° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 0.79 in precipitation 0.8 JanFebruary: 0.92 in precipitation 0.9 FebMarch: 1.39 in precipitation 1.4 MarApril: 2.57 in precipitation 2.6 AprMay: 3.42 in precipitation 3.4 MayJune: 4.75 in precipitation 4.8 JunJuly: 4.80 in precipitation 4.8 JulAugust: 3.73 in precipitation 3.7 AugSeptember: 3.18 in precipitation 3.2 SepOctober: 3.10 in precipitation 3.1 OctNovember: 1.68 in precipitation 1.7 NovDecember: 1.17 in precipitation 1.2 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Moose Lake 1 Sse, MN (10 mi away); precipitation: Moose Lake 1 Sse, MN (10 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 4a.

557184a
Carlton, MN · 9 mi
557804a
Sawyer, MN · 9 mi
557674a
Moose Lake, MN · 10 mi
557264a
Cromwell, MN · 11 mi
557494a
Holyoke, MN · 12 mi
557564a
Kerrick, MN · 12 mi
557974a
Wrenshall, MN · 13 mi
557204a
Cloquet, MN · 15 mi

Minnesota planting zones →

Questions about 55707

What planting zone is ZIP code 55707?

ZIP code 55707 (Barnum, 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 Barnum, MN?

The median last spring frost (32 °F) near 55707 is May 12; after May 26 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Moose Lake 1 Sse station.

When is the first frost in Barnum, MN?

The median first fall frost near 55707 is October 2, giving a median frost-free growing season of 144 days.

When should I plant tomatoes in 55707?

Start tomato seeds indoors around Mar 17 – Mar 31 and set transplants outside around May 19 – Jun 2, one to three weeks after the median last frost.

How much rain and snow does 55707 get?

About 31.5 inches of precipitation a year (NOAA 1991–2020 normals, Moose Lake 1 Sse station).

How hot do summers get in Barnum, MN?

The average high peaks at 80 °F in July, with about 5 days a year at 90 °F or more.

What kind of soil does 55707 have?

The USDA soil survey maps Blackhoof at the center of ZIP 55707: muck, very poorly drained, pH about 5.8 (moderately acidic).

Did spring come early in Barnum, MN in 2026?

Spring leaf-out near 55707 came on Apr 30 in 2026, 5 days later than the 1991–2020 average (Apr 25), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Barnum, MN?

Long-day onions: the longest day near 55707 is 15 h 50 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 55707 change?

Yes. The 2012 USDA map put 55707 in zone 3b; the 2023 map puts it in zone 4a. The newer map uses 1991–2020 data and more weather stations.