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

Planting zone for 56359 — Onamia, MN

ZIP code 56359 (Onamia, Mille Lacs County) is in USDA zone 4a: the coldest winter night averages −30 to −25 °F. The median last spring frost is May 10 and the first fall frost October 3.

Where ZIP 56359 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 10

First frostOct 3

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 Onamia, 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 Onamia, MN

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 10median — 50% chance of a later frost

Safe for tender plantsMay 28only 10% chance of frost after

First fall frostOctober 3median — 10% chance by Sep 19

Growing season144 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 30 and returns around October 16.

From the NOAA station Isle 12n, MN — 17 miles away, elevation 1,286 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 56359

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 29 – Apr 12

SpinachSow outdoors · Mar 29 – Apr 19

Broccoli, cabbageStart indoors · Mar 1 – Mar 15

Broccoli, cabbageTransplant · Apr 19 – May 3

Onion setsPlant outdoors · Apr 12 – Apr 26

PotatoesPlant outdoors · Apr 19 – May 3

LettuceSow outdoors · Apr 12 – Apr 26

Carrots, beetsSow outdoors · Apr 19 – May 3

TomatoesStart indoors · Mar 15 – Mar 29

TomatoesTransplant · May 17 – May 31

Peppers, eggplantStart indoors · Mar 1 – Mar 15

Peppers, eggplantTransplant · May 24 – Jun 7

BeansSow outdoors · May 17 – May 31

Sweet cornSow outdoors · May 17 – May 31

Cucumbers, squashSow outdoors · May 17 – May 31

Fall lettuce, spinachSow outdoors · Aug 8 – Aug 22

GarlicPlant cloves · Sep 19 – Oct 24

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 10) and first fall frost (Oct 3) 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 56359 came on Apr 20 — 3 days earlier than the 1991–2020 average (Apr 23).

average
Apr 232026
Apr 20

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 Onamia, MN.

Soil in Onamia, MN

The soil mapped at the center of ZIP 56359 is Rosholt — loam, well drained.

TextureLoama good balance for most vegetables

pH5.5moderately acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter1.5%low — add compost

Hydrologic groupBwater soaks in moderately

Farmland classFarmland of statewide importanceUSDA classification

Map unit: Rosholt-Chetek complex, 2 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 56359; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Onamia, MN

Summer high78 °Faverage high, July

Winter low0 °Faverage low, January

Hot days2days a year at 90 °F or more

Freezing nights176nights a year at 32 °F or less

Growing degree days2,024base 50 °F — the season’s usable heat

Longest day15 h 46 mindaylight on June 21

Shortest day8 h 37 mindaylight on December 21

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

Precipitation28.7 inper year, rain and melted snow

Snowfall32 inper year

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Isle 12n, MN (17 mi away); precipitation: Onamia Rs, MN (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 4a.

Minnesota planting zones →

Questions about 56359

What planting zone is ZIP code 56359?

ZIP code 56359 (Onamia, 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 Onamia, MN?

The median last spring frost (32 °F) near 56359 is May 10; after May 28 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Isle 12n station.

When is the first frost in Onamia, MN?

The median first fall frost near 56359 is October 3, giving a median frost-free growing season of 144 days.

When should I plant tomatoes in 56359?

Start tomato seeds indoors around Mar 15 – Mar 29 and set transplants outside around May 17 – May 31, one to three weeks after the median last frost.

How much rain and snow does 56359 get?

About 28.7 inches of precipitation a year and 32 inches of snowfall (NOAA 1991–2020 normals, Onamia Rs station).

How hot do summers get in Onamia, 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 56359 have?

The USDA soil survey maps Rosholt at the center of ZIP 56359: loam, well drained, pH about 5.5 (moderately acidic).

Did spring come early in Onamia, MN in 2026?

Spring leaf-out near 56359 came on Apr 20 in 2026, 3 days earlier than the 1991–2020 average (Apr 23), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Onamia, MN?

Long-day onions: the longest day near 56359 is 15 h 46 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 56359 change?

Yes. The 2012 USDA map put 56359 in zone 3b; the 2023 map puts it in zone 4a. The newer map uses 1991–2020 data and more weather stations.