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

Planting zone for 55790 — Tower, MN

ZIP code 55790 (Tower, St. Louis County) is in USDA zone 3a: the coldest winter night averages −40 to −35 °F. The median last spring frost is May 12 and the first fall frost October 1.

Where ZIP 55790 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.

Zone3a−40 to −35 °F

Coldest night−40 to −37.2 °C

Last frostMay 12

First frostOct 1

2012 zone3a

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 3a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Tower, 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 Tower, 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 29only 10% chance of frost after

First fall frostOctober 1median — 10% chance by Sep 17

Growing season138 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 3 and returns around October 11.

From the NOAA station Cook 8ne, MN — 9 miles away, elevation 1,355 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 55790

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 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 12) 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 55790 came on May 4 — 5 days later than the 1991–2020 average (Apr 29).

average
Apr 292026
May 4

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 3a in Minnesota

113 plants native to the lower 48 states, recorded in Minnesota, and rated by the USDA to survive −40 °F or colder — the bottom of zone 3a. 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 Tower, MN.

Soil in Tower, MN

The soil mapped at the center of ZIP 55790 is Foglake — silt loam, poorly drained.

TextureSilt loama good balance for most vegetables

pH5.9moderately acidic; most vegetables like 6.0–7.0

DrainagePoorly drainedconsider raised beds

Organic matter6%high

Hydrologic groupC/Dslow when drained; wet otherwise

Farmland classNot prime farmlandUSDA classification

Map unit: Foglake-Babbitt, bouldery, complex, 0 to 4 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 55790; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Tower, MN

Summer high77 °Faverage high, July

Winter low−7 °Faverage low, January

Hot days4days a year at 90 °F or more

Freezing nights220nights a year at 32 °F or less

Growing degree days1,452base 50 °F — the season’s usable heat

Longest day16 h 01 mindaylight on June 21

Shortest day8 h 23 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

Snowfall69 inper year

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Tower 2s, MN (6 mi away); precipitation: Tower 2s, MN (6 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

557823a

Soudan, MN · 8 mi

557323a

Embarrass, MN · 11 mi

Minnesota planting zones →

Questions about 55790

What planting zone is ZIP code 55790?

ZIP code 55790 (Tower, MN) is in USDA hardiness zone 3a on the 2023 map: the coldest night of an average winter reaches −40 to −35 °F (−40 to −37.2 °C).

When is the last frost in Tower, MN?

The median last spring frost (32 °F) near 55790 is May 12; after May 29 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Cook 8ne station.

When is the first frost in Tower, MN?

The median first fall frost near 55790 is October 1, giving a median frost-free growing season of 138 days.

When should I plant tomatoes in 55790?

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 55790 get?

About 28.2 inches of precipitation a year and 69 inches of snowfall (NOAA 1991–2020 normals, Tower 2s station).

How hot do summers get in Tower, MN?

The average high peaks at 77 °F in July, with about 4 days a year at 90 °F or more.

What kind of soil does 55790 have?

The USDA soil survey maps Foglake at the center of ZIP 55790: silt loam, poorly drained, pH about 5.9 (moderately acidic).

Did spring come early in Tower, MN in 2026?

Spring leaf-out near 55790 came on May 4 in 2026, 5 days later than the 1991–2020 average (Apr 29), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Tower, MN?

Long-day onions: the longest day near 55790 is 16 h 01 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).