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

Planting zone for 55921 — Caledonia, MN

ZIP code 55921 (Caledonia, Houston County) is in USDA zone 5a: the coldest winter night averages −20 to −15 °F. The median last spring frost is April 29 and the first fall frost October 10.

Where ZIP 55921 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.

Zone5a−20 to −15 °F
Coldest night−28.9 to −26.1 °C
Last frostApr 29
First frostOct 10
2012 zone4b

Was 4b 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 5a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Caledonia, 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 Caledonia, MN

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 29median — 50% chance of a later frost
Safe for tender plantsMay 11only 10% chance of frost after
First fall frostOctober 10median — 10% chance by Sep 28
Growing season165 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 18 and returns around October 23.

From the NOAA station Caledonia, MN — within 1 mile, elevation 1,165 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 55921

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 18 – Apr 1
SpinachSow outdoors · Mar 18 – Apr 8
Broccoli, cabbageStart indoors · Feb 18 – Mar 4
Broccoli, cabbageTransplant · Apr 8 – Apr 22
Onion setsPlant outdoors · Apr 1 – Apr 15
PotatoesPlant outdoors · Apr 8 – Apr 22
LettuceSow outdoors · Apr 1 – Apr 15
Carrots, beetsSow outdoors · Apr 8 – Apr 22
TomatoesStart indoors · Mar 4 – Mar 18
TomatoesTransplant · May 6 – May 20
Peppers, eggplantStart indoors · Feb 18 – Mar 4
Peppers, eggplantTransplant · May 13 – May 27
BeansSow outdoors · May 6 – May 20
Sweet cornSow outdoors · May 6 – May 20
Cucumbers, squashSow outdoors · May 6 – May 20
Fall lettuce, spinachSow outdoors · Aug 15 – Aug 29
GarlicPlant cloves · Sep 26 – Oct 31
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 29) and first fall frost (Oct 10) 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 55921 came on Mar 30 — 16 days earlier than the 1991–2020 average (Apr 15).

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 5a in Minnesota

521 plants native to the lower 48 states, recorded in Minnesota, and rated by the USDA to survive −20 °F or colder — the bottom of zone 5a. Each links to its USDA PLANTS profile.

Trees 47

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 92

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 201

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 164

alkali cordgrass3 ft · blooms late summer · high shade tolerance · to −38 °FAmerican beachgrass2.5 ft · blooms spring · high shade tolerance · to −28 °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 °F

Vines 5

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 °Fsummer grape30 ft · blooms late spring · low shade tolerance · to −23 °FVirginia creeper1 ft · blooms late spring · medium shade tolerance · to −28 °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 Caledonia, MN.

Soil in Caledonia, MN

The soil mapped at the center of ZIP 55921 is Eitzen — silt loam, well drained.

TextureSilt loama good balance for most vegetables
pH6.5neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter3%moderate
Hydrologic groupBwater soaks in moderately
Farmland classNot prime farmlandUSDA classification

Map unit: Eitzen silt loam, channeled, 1 to 6 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 55921; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Caledonia, MN

Summer high81 °Faverage high, July
Winter low8 °Faverage low, January
Hot days5days a year at 90 °F or more
Freezing nights160nights a year at 32 °F or less
Growing degree days2,593base 50 °F — the season’s usable heat
Longest day15 h 26 mindaylight on June 21
Shortest day8 h 56 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation38.3 inper year, rain and melted snow
Snowfall45 inper year; 82 days with snow on the ground

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 24 °F, low 8 °F 24°8° JanFebruary: average high 29 °F, low 11 °F 29°11° FebMarch: average high 41 °F, low 23 °F 41°23° MarApril: average high 56 °F, low 35 °F 56°35° AprMay: average high 68 °F, low 47 °F 68°47° MayJune: average high 77 °F, low 58 °F 77°58° JunJuly: average high 81 °F, low 62 °F 81°62° JulAugust: average high 79 °F, low 59 °F 79°59° AugSeptember: average high 72 °F, low 51 °F 72°51° SepOctober: average high 59 °F, low 39 °F 59°39° OctNovember: average high 43 °F, low 26 °F 43°26° NovDecember: average high 30 °F, low 15 °F 30°15° Dec

Precipitation by month inches · ❄ = snowfall

0″2″4″6″January: 1.12 in precipitation, 10.4 in snowfall 1.1❄10 JanFebruary: 1.16 in precipitation, 10.6 in snowfall 1.2❄11 FebMarch: 2.00 in precipitation, 7.4 in snowfall 2.0❄7 MarApril: 3.96 in precipitation, 3.2 in snowfall 4.0❄3 AprMay: 4.84 in precipitation 4.8 MayJune: 6.06 in precipitation 6.1 JunJuly: 4.31 in precipitation 4.3 JulAugust: 4.47 in precipitation 4.5 AugSeptember: 4.04 in precipitation 4.0 SepOctober: 2.96 in precipitation, 0.3 in snowfall 3.0 OctNovember: 1.80 in precipitation, 2.8 in snowfall 1.8❄3 NovDecember: 1.60 in precipitation, 10.1 in snowfall 1.6❄10 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Caledonia, MN (within 1 mile); precipitation: Caledonia, MN (within 1 mile). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 5a.

559195a
Brownsville, MN · 9 mi
559315a
Eitzen, MN · 9 mi
559745a
Spring Grove, MN · 9 mi
559415a
Hokah, MN · 10 mi
521605a
New Albin, IA · 12 mi
521405a
Dorchester, IA · 12 mi
559435a
Houston, MN · 12 mi
559475a
La Crescent, MN · 15 mi

Minnesota planting zones →

Questions about 55921

What planting zone is ZIP code 55921?

ZIP code 55921 (Caledonia, MN) is in USDA hardiness zone 5a on the 2023 map: the coldest night of an average winter reaches −20 to −15 °F (−28.9 to −26.1 °C).

When is the last frost in Caledonia, MN?

The median last spring frost (32 °F) near 55921 is April 29; after May 11 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Caledonia station.

When is the first frost in Caledonia, MN?

The median first fall frost near 55921 is October 10, giving a median frost-free growing season of 165 days.

When should I plant tomatoes in 55921?

Start tomato seeds indoors around Mar 4 – Mar 18 and set transplants outside around May 6 – May 20, one to three weeks after the median last frost.

How much rain and snow does 55921 get?

About 38.3 inches of precipitation a year and 45 inches of snowfall (NOAA 1991–2020 normals, Caledonia station).

How hot do summers get in Caledonia, MN?

The average high peaks at 81 °F in July, with about 5 days a year at 90 °F or more.

What kind of soil does 55921 have?

The USDA soil survey maps Eitzen at the center of ZIP 55921: silt loam, well drained, pH about 6.5 (neutral).

Did spring come early in Caledonia, MN in 2026?

Spring leaf-out near 55921 came on Mar 30 in 2026, 16 days earlier than the 1991–2020 average (Apr 15), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Caledonia, MN?

Long-day onions: the longest day near 55921 is 15 h 26 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 55921 change?

Yes. The 2012 USDA map put 55921 in zone 4b; the 2023 map puts it in zone 5a. The newer map uses 1991–2020 data and more weather stations.