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

Planting zone for 49638 — Harrietta, MI

ZIP code 49638 (Harrietta, Wexford County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is May 28 and the first fall frost September 25.

Where ZIP 49638 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 frostMay 28

First frostSep 25

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 Harrietta, 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 Harrietta, MI

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 28median — 50% chance of a later frost

Safe for tender plantsJune 13only 10% chance of frost after

First fall frostSeptember 25median — 10% chance by Sep 8

Growing season119 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 18 and returns around October 8.

From the NOAA station Wellston 1n, MI — 11 miles away, elevation 774 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 49638

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 16 – Apr 30

SpinachSow outdoors · Apr 16 – May 7

Broccoli, cabbageStart indoors · Mar 19 – Apr 2

Broccoli, cabbageTransplant · May 7 – May 21

Onion setsPlant outdoors · Apr 30 – May 14

PotatoesPlant outdoors · May 7 – May 21

LettuceSow outdoors · Apr 30 – May 14

Carrots, beetsSow outdoors · May 7 – May 21

TomatoesStart indoors · Apr 2 – Apr 16

TomatoesTransplant · Jun 4 – Jun 18

Peppers, eggplantStart indoors · Mar 19 – Apr 2

Peppers, eggplantTransplant · Jun 11 – Jun 25

BeansSow outdoors · Jun 4 – Jun 18

Sweet cornSow outdoors · Jun 4 – Jun 18

Cucumbers, squashSow outdoors · Jun 4 – Jun 18

Fall lettuce, spinachSow outdoors · Jul 31 – Aug 14

GarlicPlant cloves · Sep 11 – Oct 16

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 28) and first fall frost (Sep 25) 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 49638 came on Apr 15 — 4 days earlier than the 1991–2020 average (Apr 19).

average
Apr 192026
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 5b in Michigan

564 plants native to the lower 48 states, recorded in Michigan, 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 Harrietta, MI.

Soil in Harrietta, MI

The soil mapped at the center of ZIP 49638 is Allendale — loamy sand, somewhat poorly drained.

TextureLoamy sanddrains and warms fast; dries out and needs more feeding

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

DrainageSomewhat poorly drainedconsider raised beds

Organic matter3%moderate

Hydrologic groupDwater soaks in very slowly

Farmland classFarmland of local importanceUSDA classification

Map unit: Allendale loamy sand, 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 49638; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Harrietta, MI

Summer high81 °Faverage high, July

Winter low12 °Faverage low, January

Hot days8days a year at 90 °F or more

Freezing nights171nights a year at 32 °F or less

Growing degree days2,054base 50 °F — the season’s usable heat

Longest day15 h 31 mindaylight on June 21

Shortest day8 h 51 mindaylight on December 21

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

Precipitation36.3 inper year, rain and melted snow

Snowfall93 inper year; 110 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: Wellston 1n, MI (11 mi away); precipitation: Wellston Tippy Dam, MI (9 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

Michigan planting zones →

Questions about 49638

What planting zone is ZIP code 49638?

ZIP code 49638 (Harrietta, MI) 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 Harrietta, MI?

The median last spring frost (32 °F) near 49638 is May 28; after June 13 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Wellston 1n station.

When is the first frost in Harrietta, MI?

The median first fall frost near 49638 is September 25, giving a median frost-free growing season of 119 days.

When should I plant tomatoes in 49638?

Start tomato seeds indoors around Apr 2 – Apr 16 and set transplants outside around Jun 4 – Jun 18, one to three weeks after the median last frost.

How much rain and snow does 49638 get?

About 36.3 inches of precipitation a year and 93 inches of snowfall (NOAA 1991–2020 normals, Wellston Tippy Dam station).

How hot do summers get in Harrietta, MI?

The average high peaks at 81 °F in July, with about 8 days a year at 90 °F or more.

What kind of soil does 49638 have?

The USDA soil survey maps Allendale at the center of ZIP 49638: loamy sand, somewhat poorly drained, pH about 5.8 (moderately acidic).

Did spring come early in Harrietta, MI in 2026?

Spring leaf-out near 49638 came on Apr 15 in 2026, 4 days earlier than the 1991–2020 average (Apr 19), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Harrietta, MI?

Long-day onions: the longest day near 49638 is 15 h 31 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 49638 change?

Yes. The 2012 USDA map put 49638 in zone 5a; the 2023 map puts it in zone 5b. The newer map uses 1991–2020 data and more weather stations.