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

Planting zone for Mequon, WI

Mequon, WI is in USDA zones 5b to 6a across its 2 ZIP codes. The median last spring frost is April 23 and the first fall frost October 24.

Mequon on the zone map

Outlined: its 2 ZIP code areas · 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.

Zones5b–6a−15 to −5 °F

ZIP codes2

Last frostApr 23

First frostOct 24

Growing season182 days

5b 1 ZIP 6a 1 ZIP

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Mequon, 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 Mequon, WI

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 23median — 50% chance of a later frost

Safe for tender plantsMay 9only 10% chance of frost after

First fall frostOctober 24median — 10% chance by Oct 8

Growing season182 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 11 and returns around November 2.

From the NOAA station Grafton Wwtp, WI, elevation 742 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 Mequon

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 12 – Mar 26

SpinachSow outdoors · Mar 12 – Apr 2

Broccoli, cabbageStart indoors · Feb 12 – Feb 26

Broccoli, cabbageTransplant · Apr 2 – Apr 16

Onion setsPlant outdoors · Mar 26 – Apr 9

PotatoesPlant outdoors · Apr 2 – Apr 16

LettuceSow outdoors · Mar 26 – Apr 9

Carrots, beetsSow outdoors · Apr 2 – Apr 16

TomatoesStart indoors · Feb 26 – Mar 12

TomatoesTransplant · Apr 30 – May 14

Peppers, eggplantStart indoors · Feb 12 – Feb 26

Peppers, eggplantTransplant · May 7 – May 21

BeansSow outdoors · Apr 30 – May 14

Sweet cornSow outdoors · Apr 30 – May 14

Cucumbers, squashSow outdoors · Apr 30 – May 14

Fall lettuce, spinachSow outdoors · Aug 29 – Sep 12

GarlicPlant cloves · Oct 10 – Nov 14

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 23) and first fall frost (Oct 24) 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 53097 came on Apr 1 — 12 days earlier than the 1991–2020 average (Apr 13).

average
Apr 132026
Apr 1

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 Mequon, WI.

Soil in Mequon, WI

The soil mapped at the center of ZIP 53097 is Ozaukee — silt loam, moderately well drained.

TextureSilt loama good balance for most vegetables

pH7.0neutral; most vegetables like 6.0–7.0

DrainageModerately well drainednatural drainage class

Organic matter2%moderate

Hydrologic groupCwater soaks in slowly

Farmland classprime farmlandUSDA classification

Map unit: Ozaukee silt loam, high carbonate substratum, 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 53097; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Mequon, WI

Summer high81 °Faverage high, July

Winter low17 °Faverage low, January

Hot days6days a year at 90 °F or more

Freezing nights134nights a year at 32 °F or less

Growing degree days2,586base 50 °F — the season’s usable heat

Longest day15 h 23 mindaylight on June 21

Shortest day8 h 58 mindaylight on December 21

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

Precipitation35.5 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: Grafton Wwtp, WI (6 mi away); precipitation: Germantown 1.3 Ne, WI (5 mi away). Daylight is calculated from latitude.

ZIP codes in Mequon

Wisconsin planting zones →

Questions about Mequon

What planting zone is Mequon, WI?

Mequon, WI is in USDA hardiness zones 5b to 6a on the 2023 map (5b: −15 to −10 °F; 6a: −10 to −5 °F).

When is the last frost in Mequon, WI?

The median last spring frost is April 23 and the median first fall frost is October 24 (NOAA 1991–2020 normals, Grafton Wwtp station).

When can I plant a garden in Mequon, WI?

Cool-season crops like peas and spinach go in around Mar 12 – Apr 2; tomatoes, peppers, beans and squash after about Apr 30, once frost risk has passed.

What kind of onions grow in Mequon, WI?

Long-day onions: the longest day is 15 h 23 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

How much rain and snow does Mequon, WI get?

About 35.5 inches of precipitation a year (NOAA 1991–2020 normals).