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

Planting zone for 46531 — Grovertown, IN

ZIP code 46531 (Grovertown, Starke County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is April 26 and the first fall frost October 19.

Where ZIP 46531 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 26
First frostOct 19
2012 zone5b

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 5b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Grovertown, IN…

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 Grovertown, IN

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 26median — 50% chance of a later frost
Safe for tender plantsMay 12only 10% chance of frost after
First fall frostOctober 19median — 10% chance by Oct 5
Growing season174 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 15 and returns around October 30.

From the NOAA station Knox Wwtp, IN — 7 miles away, elevation 689 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 46531

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 15 – Mar 29
SpinachSow outdoors · Mar 15 – Apr 5
Broccoli, cabbageStart indoors · Feb 15 – Mar 1
Broccoli, cabbageTransplant · Apr 5 – Apr 19
Onion setsPlant outdoors · Mar 29 – Apr 12
PotatoesPlant outdoors · Apr 5 – Apr 19
LettuceSow outdoors · Mar 29 – Apr 12
Carrots, beetsSow outdoors · Apr 5 – Apr 19
TomatoesStart indoors · Mar 1 – Mar 15
TomatoesTransplant · May 3 – May 17
Peppers, eggplantStart indoors · Feb 15 – Mar 1
Peppers, eggplantTransplant · May 10 – May 24
BeansSow outdoors · May 3 – May 17
Sweet cornSow outdoors · May 3 – May 17
Cucumbers, squashSow outdoors · May 3 – May 17
Fall lettuce, spinachSow outdoors · Aug 24 – Sep 7
GarlicPlant cloves · Oct 5 – Nov 9
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 26) and first fall frost (Oct 19) 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 46531 came on Mar 16 — 19 days earlier than the 1991–2020 average (Apr 4).

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 Indiana

533 plants native to the lower 48 states, recorded in Indiana, and rated by the USDA to survive −15 °F or colder — the bottom of zone 5b. Each links to its USDA PLANTS profile.

Trees 70

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican beech80 ft · blooms mid spring · low shade tolerance · to −44 °FAmerican chestnut115 ft · blooms early summer · high shade tolerance · to −33 °FAmerican elm120 ft · blooms early spring · medium shade tolerance · to −46 °FAmerican sycamore100 ft · blooms spring · medium shade tolerance · to −34 °Farborvitae50 ft · blooms mid spring · medium shade tolerance · to −33 °F

Shrubs 99

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 holly40 ft · blooms mid spring · low shade tolerance · to −20 °F

Wildflowers & perennials 191

American 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 °FAmerican pokeweed7 ft · blooms mid summer · low shade tolerance · to −33 °FAmerican speedwell0.8 ft · blooms mid summer · low shade tolerance · to −38 °F

Grasses 156

American 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 °Fbeaked spikerush3 ft · blooms late spring · high shade tolerance · to −28 °FBebb's sedge3 ft · blooms late spring · low shade tolerance · to −38 °FBicknell's sedge3 ft · blooms late spring · low shade tolerance · to −38 °F

Vines 7

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Ffrost grape83 ft · blooms late spring · medium shade tolerance · to −23 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Fsummer grape30 ft · blooms late spring · low shade tolerance · to −23 °Ftrumpet honeysuckle16 ft · blooms late summer · low shade tolerance · to −33 °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 Grovertown, IN.

Soil in Grovertown, IN

The soil mapped at the center of ZIP 46531 is Brems — sand, moderately well drained.

TextureSanddrains and warms fast; dries out and needs more feeding
pH5.8moderately acidic; most vegetables like 6.0–7.0
DrainageModerately well drainednatural drainage class
Organic matter1%low — add compost
Hydrologic groupAwater soaks in fast
Farmland classNot prime farmlandUSDA classification

Map unit: Brems sand, 0 to 3 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 46531; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Grovertown, IN

Summer high82 °Faverage high, July
Winter low16 °Faverage low, January
Hot days7days a year at 90 °F or more
Freezing nights137nights a year at 32 °F or less
Growing degree days2,926base 50 °F — the season’s usable heat
Longest day15 h 10 mindaylight on June 21
Shortest day9 h 11 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation42.2 inper year, rain and melted snow
Snowfall29 inper year; 32 days with snow on the ground

Average high and low, by month

10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 32 °F, low 16 °F 32°16° JanFebruary: average high 35 °F, low 18 °F 35°18° FebMarch: average high 47 °F, low 28 °F 47°28° MarApril: average high 61 °F, low 38 °F 61°38° AprMay: average high 71 °F, low 49 °F 71°49° MayJune: average high 80 °F, low 59 °F 80°59° JunJuly: average high 82 °F, low 62 °F 82°62° JulAugust: average high 81 °F, low 60 °F 81°60° AugSeptember: average high 74 °F, low 52 °F 74°52° SepOctober: average high 63 °F, low 42 °F 63°42° OctNovember: average high 49 °F, low 32 °F 49°32° NovDecember: average high 37 °F, low 22 °F 37°22° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″January: 2.73 in precipitation, 9.7 in snowfall 2.7❄10 JanFebruary: 2.44 in precipitation, 7.5 in snowfall 2.4❄8 FebMarch: 2.53 in precipitation, 3.4 in snowfall 2.5❄3 MarApril: 3.75 in precipitation, 0.2 in snowfall 3.8 AprMay: 4.45 in precipitation 4.5 MayJune: 4.65 in precipitation 4.7 JunJuly: 4.35 in precipitation 4.3 JulAugust: 4.48 in precipitation 4.5 AugSeptember: 3.47 in precipitation 3.5 SepOctober: 3.59 in precipitation 3.6 OctNovember: 3.17 in precipitation, 2 in snowfall 3.2❄2 NovDecember: 2.61 in precipitation, 5.7 in snowfall 2.6❄6 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Knox Wwtp, IN (7 mi away); precipitation: Knox Wwtp, IN (7 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

465136a
Donaldson, IN · 4 mi
465325b
Hamlet, IN · 7 mi
465345b
Knox, IN · 7 mi
465726a
Tyner, IN · 7 mi
465746a
Walkerton, IN · 9 mi
465636a
Plymouth, IN · 10 mi
465116a
Culver, IN · 11 mi
463465b
Kingsford Heights, IN · 12 mi

Indiana planting zones →

Questions about 46531

What planting zone is ZIP code 46531?

ZIP code 46531 (Grovertown, IN) 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 Grovertown, IN?

The median last spring frost (32 °F) near 46531 is April 26; after May 12 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Knox Wwtp station.

When is the first frost in Grovertown, IN?

The median first fall frost near 46531 is October 19, giving a median frost-free growing season of 174 days.

When should I plant tomatoes in 46531?

Start tomato seeds indoors around Mar 1 – Mar 15 and set transplants outside around May 3 – May 17, one to three weeks after the median last frost.

How much rain and snow does 46531 get?

About 42.2 inches of precipitation a year and 29 inches of snowfall (NOAA 1991–2020 normals, Knox Wwtp station).

How hot do summers get in Grovertown, IN?

The average high peaks at 82 °F in July, with about 7 days a year at 90 °F or more.

What kind of soil does 46531 have?

The USDA soil survey maps Brems at the center of ZIP 46531: sand, moderately well drained, pH about 5.8 (moderately acidic).

Did spring come early in Grovertown, IN in 2026?

Spring leaf-out near 46531 came on Mar 16 in 2026, 19 days earlier than the 1991–2020 average (Apr 4), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Grovertown, IN?

Long-day onions: the longest day near 46531 is 15 h 10 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).