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

Planting zone for 55779 — Saginaw, MN

ZIP code 55779 (Saginaw, St. Louis County) is in USDA zone 4a: the coldest winter night averages −30 to −25 °F. The median last spring frost is May 18 and the first fall frost October 1.

Where ZIP 55779 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 18

First frostOct 1

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 Saginaw, 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 Saginaw, MN

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 18median — 50% chance of a later frost

Safe for tender plantsJune 3only 10% chance of frost after

First fall frostOctober 1median — 10% chance by Sep 19

Growing season135 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 4 and returns around October 12.

From the NOAA station Duluth NWS, MN — 12 miles away, elevation 1,434 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 55779

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 6 – Apr 20

SpinachSow outdoors · Apr 6 – Apr 27

Broccoli, cabbageStart indoors · Mar 9 – Mar 23

Broccoli, cabbageTransplant · Apr 27 – May 11

Onion setsPlant outdoors · Apr 20 – May 4

PotatoesPlant outdoors · Apr 27 – May 11

LettuceSow outdoors · Apr 20 – May 4

Carrots, beetsSow outdoors · Apr 27 – May 11

TomatoesStart indoors · Mar 23 – Apr 6

TomatoesTransplant · May 25 – Jun 8

Peppers, eggplantStart indoors · Mar 9 – Mar 23

Peppers, eggplantTransplant · Jun 1 – Jun 15

BeansSow outdoors · May 25 – Jun 8

Sweet cornSow outdoors · May 25 – Jun 8

Cucumbers, squashSow outdoors · May 25 – Jun 8

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 18) 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 55779 came on Apr 30 — 3 days later than the 1991–2020 average (Apr 27).

average
Apr 272026
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 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 Saginaw, MN.

Soil in Saginaw, MN

The soil mapped at the center of ZIP 55779 is Hermantown — silt loam, somewhat poorly drained.

TextureSilt loama good balance for most vegetables

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

DrainageSomewhat poorly drainedconsider raised beds

Organic matter5%high

Hydrologic groupC/Dslow when drained; wet otherwise

Farmland classFarmland of statewide importanceUSDA classification

Map unit: Hermantown silt loam, 1 to 3 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 55779; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Saginaw, MN

Summer high76 °Faverage high, July

Winter low1 °Faverage low, January

Hot days1days a year at 90 °F or more

Freezing nights184nights a year at 32 °F or less

Growing degree days1,706base 50 °F — the season’s usable heat

Longest day15 h 53 mindaylight on June 21

Shortest day8 h 31 mindaylight on December 21

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

Precipitation28.2 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: Duluth NWS, MN (12 mi away); precipitation: Saginaw 1.5 Sw, 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.

Brookston, MN · 13 mi

558104b

Duluth, MN · 14 mi

Minnesota planting zones →

Questions about 55779

What planting zone is ZIP code 55779?

ZIP code 55779 (Saginaw, 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 Saginaw, MN?

The median last spring frost (32 °F) near 55779 is May 18; after June 3 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Duluth NWS station.

When is the first frost in Saginaw, MN?

The median first fall frost near 55779 is October 1, giving a median frost-free growing season of 135 days.

When should I plant tomatoes in 55779?

Start tomato seeds indoors around Mar 23 – Apr 6 and set transplants outside around May 25 – Jun 8, one to three weeks after the median last frost.

How much rain and snow does 55779 get?

About 28.2 inches of precipitation a year (NOAA 1991–2020 normals, Saginaw 1.5 Sw station).

How hot do summers get in Saginaw, MN?

The average high peaks at 76 °F in July, with about 1 days a year at 90 °F or more.

What kind of soil does 55779 have?

The USDA soil survey maps Hermantown at the center of ZIP 55779: silt loam, somewhat poorly drained, pH about 5.6 (moderately acidic).

Did spring come early in Saginaw, MN in 2026?

Spring leaf-out near 55779 came on Apr 30 in 2026, 3 days later than the 1991–2020 average (Apr 27), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Saginaw, MN?

Long-day onions: the longest day near 55779 is 15 h 53 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 55779 change?

Yes. The 2012 USDA map put 55779 in zone 3b; the 2023 map puts it in zone 4a. The newer map uses 1991–2020 data and more weather stations.