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

Planting zone for 53551 — Lake Mills, WI

ZIP code 53551 (Lake Mills, Jefferson County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is April 29 and the first fall frost October 14.

Where ZIP 53551 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.

Zone5b−15 to −10 °F

Coldest night−26.1 to −23.3 °C

Last frostApr 29

First frostOct 14

2012 zone5a

Was 5a 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 5b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Lake Mills, WI…

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 Lake Mills, WI

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 13only 10% chance of frost after

First fall frostOctober 14median — 10% chance by Sep 29

Growing season167 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 17 and returns around October 26.

From the NOAA station Lake Mills Wwtp, WI — within 1 mile, elevation 810 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 53551

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 19 – Sep 2

GarlicPlant cloves · Sep 30 – Nov 4

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 29) and first fall frost (Oct 14) 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 53551 came on Mar 30 — 13 days earlier than the 1991–2020 average (Apr 12).

average
Apr 122026
Mar 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 5b in Wisconsin

518 plants native to the lower 48 states, recorded in Wisconsin, and rated by the USDA to survive −15 °F or colder — the bottom of zone 5b. 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 Lake Mills, WI.

Soil in Lake Mills, WI

The soil mapped at the center of ZIP 53551 is Fox — silt loam, well drained.

TextureSilt loama good balance for most vegetables

pH6.2slightly acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter2%moderate

Hydrologic groupBwater soaks in moderately

Farmland classprime farmlandUSDA classification

Map unit: Fox silt loam, 2 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 53551; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Lake Mills, WI

Summer high84 °Faverage high, July

Winter low11 °Faverage low, January

Hot days12days a year at 90 °F or more

Freezing nights145nights a year at 32 °F or less

Growing degree days2,830base 50 °F — the season’s usable heat

Longest day15 h 22 mindaylight on June 21

Shortest day8 h 59 mindaylight on December 21

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

Precipitation37 inper year, rain and melted snow

Snowfall42 inper year; 70 days with snow on the ground

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

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

Nearby ZIP codes

All 8 nearest ZIP codes share zone 5b.

530385b

Johnson Creek, WI · 6 mi

Jefferson, WI · 10 mi

535595b

Marshall, WI · 10 mi

530945b

Watertown, WI · 10 mi

535385b

Fort Atkinson, WI · 12 mi

Wisconsin planting zones →

Questions about 53551

What planting zone is ZIP code 53551?

ZIP code 53551 (Lake Mills, WI) is in USDA hardiness zone 5b on the 2023 map: the coldest night of an average winter reaches −15 to −10 °F (−26.1 to −23.3 °C).

When is the last frost in Lake Mills, WI?

The median last spring frost (32 °F) near 53551 is April 29; after May 13 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Lake Mills Wwtp station.

When is the first frost in Lake Mills, WI?

The median first fall frost near 53551 is October 14, giving a median frost-free growing season of 167 days.

When should I plant tomatoes in 53551?

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 53551 get?

About 37 inches of precipitation a year and 42 inches of snowfall (NOAA 1991–2020 normals, Lake Mills Wwtp station).

How hot do summers get in Lake Mills, WI?

The average high peaks at 84 °F in July, with about 12 days a year at 90 °F or more.

What kind of soil does 53551 have?

The USDA soil survey maps Fox at the center of ZIP 53551: silt loam, well drained, pH about 6.2 (slightly acidic).

Did spring come early in Lake Mills, WI in 2026?

Spring leaf-out near 53551 came on Mar 30 in 2026, 13 days earlier than the 1991–2020 average (Apr 12), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Lake Mills, WI?

Long-day onions: the longest day near 53551 is 15 h 22 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 53551 change?

Yes. The 2012 USDA map put 53551 in zone 5a; the 2023 map puts it in zone 5b. The newer map uses 1991–2020 data and more weather stations.