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

Planting zone for 49031 — Cassopolis, MI

ZIP code 49031 (Cassopolis, Cass County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is May 4 and the first fall frost October 11.

Where ZIP 49031 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.

Zone6a−10 to −5 °F

Coldest night−23.3 to −20.6 °C

Last frostMay 4

First frostOct 11

2012 zone6a

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 6a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Cassopolis, MI…

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 Cassopolis, MI

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 4median — 50% chance of a later frost

Safe for tender plantsMay 22only 10% chance of frost after

First fall frostOctober 11median — 10% chance by Sep 27

Growing season158 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 24 and returns around October 26.

From the NOAA station Dowagiac 1 W, MI — 10 miles away, 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 49031

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 23 – Apr 6

SpinachSow outdoors · Mar 23 – Apr 13

Broccoli, cabbageStart indoors · Feb 23 – Mar 9

Broccoli, cabbageTransplant · Apr 13 – Apr 27

Onion setsPlant outdoors · Apr 6 – Apr 20

PotatoesPlant outdoors · Apr 13 – Apr 27

LettuceSow outdoors · Apr 6 – Apr 20

Carrots, beetsSow outdoors · Apr 13 – Apr 27

TomatoesStart indoors · Mar 9 – Mar 23

TomatoesTransplant · May 11 – May 25

Peppers, eggplantStart indoors · Feb 23 – Mar 9

Peppers, eggplantTransplant · May 18 – Jun 1

BeansSow outdoors · May 11 – May 25

Sweet cornSow outdoors · May 11 – May 25

Cucumbers, squashSow outdoors · May 11 – May 25

Fall lettuce, spinachSow outdoors · Aug 16 – Aug 30

GarlicPlant cloves · Sep 27 – Nov 1

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 4) and first fall frost (Oct 11) 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 49031 came on Mar 25 — 12 days earlier than the 1991–2020 average (Apr 6).

average
Apr 62026
Mar 25

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 6a in Michigan

580 plants native to the lower 48 states, recorded in Michigan, and rated by the USDA to survive −10 °F or colder — the bottom of zone 6a. 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 Cassopolis, MI.

Soil in Cassopolis, MI

The soil mapped at the center of ZIP 49031 is Kalamazoo — loam, well drained.

TextureLoama good balance for most vegetables

pH5.8moderately acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter1.5%low — add compost

Hydrologic groupCwater soaks in slowly

Farmland classprime farmlandUSDA classification

Map unit: Kalamazoo 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 49031; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Cassopolis, MI

Summer high82 °Faverage high, July

Winter low16 °Faverage low, January

Hot days11days a year at 90 °F or more

Freezing nights145nights a year at 32 °F or less

Growing degree days2,634base 50 °F — the season’s usable heat

Longest day15 h 14 mindaylight on June 21

Shortest day9 h 07 mindaylight on December 21

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

Precipitation41.7 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: Dowagiac 1 W, MI (10 mi away); precipitation: Dowagiac 1 W, MI (10 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6a.

490956a

Vandalia, MI · 5 mi

491126a

Edwardsburg, MI · 8 mi

Marcellus, MI · 12 mi

Michigan planting zones →

Questions about 49031

What planting zone is ZIP code 49031?

ZIP code 49031 (Cassopolis, MI) is in USDA hardiness zone 6a on the 2023 map: the coldest night of an average winter reaches −10 to −5 °F (−23.3 to −20.6 °C).

When is the last frost in Cassopolis, MI?

The median last spring frost (32 °F) near 49031 is May 4; after May 22 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Dowagiac 1 W station.

When is the first frost in Cassopolis, MI?

The median first fall frost near 49031 is October 11, giving a median frost-free growing season of 158 days.

When should I plant tomatoes in 49031?

Start tomato seeds indoors around Mar 9 – Mar 23 and set transplants outside around May 11 – May 25, one to three weeks after the median last frost.

How much rain and snow does 49031 get?

About 41.7 inches of precipitation a year (NOAA 1991–2020 normals, Dowagiac 1 W station).

How hot do summers get in Cassopolis, MI?

The average high peaks at 82 °F in July, with about 11 days a year at 90 °F or more.

What kind of soil does 49031 have?

The USDA soil survey maps Kalamazoo at the center of ZIP 49031: loam, well drained, pH about 5.8 (moderately acidic).

Did spring come early in Cassopolis, MI in 2026?

Spring leaf-out near 49031 came on Mar 25 in 2026, 12 days earlier than the 1991–2020 average (Apr 6), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Cassopolis, MI?

Long-day onions: the longest day near 49031 is 15 h 14 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).