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

Planting zone for 42457 — Smith Mills, KY

ZIP code 42457 (Smith Mills, Henderson County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is April 7 and the first fall frost October 28.

Where ZIP 42457 is

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.

Zone7a0 to 5 °F
Coldest night−17.8 to −15 °C
Last frostApr 7
First frostOct 28
2012 zone6b

Was 6b 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 7a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Smith Mills, KY…

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 Smith Mills, KY

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 7median — 50% chance of a later frost
Safe for tender plantsApril 27only 10% chance of frost after
First fall frostOctober 28median — 10% chance by Oct 10
Growing season202 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 30 and returns around November 7.

From the NOAA station Mt Vernon, IN — 9 miles away, elevation 358 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 42457

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 24 – Mar 10
SpinachSow outdoors · Feb 24 – Mar 17
Broccoli, cabbageStart indoors · Jan 27 – Feb 10
Broccoli, cabbageTransplant · Mar 17 – Mar 31
Onion setsPlant outdoors · Mar 10 – Mar 24
PotatoesPlant outdoors · Mar 17 – Mar 31
LettuceSow outdoors · Mar 10 – Mar 24
Carrots, beetsSow outdoors · Mar 17 – Mar 31
TomatoesStart indoors · Feb 10 – Feb 24
TomatoesTransplant · Apr 14 – Apr 28
Peppers, eggplantStart indoors · Jan 27 – Feb 10
Peppers, eggplantTransplant · Apr 21 – May 5
BeansSow outdoors · Apr 14 – Apr 28
Sweet cornSow outdoors · Apr 14 – Apr 28
Cucumbers, squashSow outdoors · Apr 14 – Apr 28
Fall lettuce, spinachSow outdoors · Sep 2 – Sep 16
GarlicPlant cloves · Oct 14 – Nov 18
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 7) and first fall frost (Oct 28) 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 42457 came on Mar 2 — 8 days earlier than the 1991–2020 average (Mar 10).

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 7a in Kentucky

547 plants native to the lower 48 states, recorded in Kentucky, and rated by the USDA to survive 0 °F or colder — the bottom of zone 7a. Each links to its USDA PLANTS profile.

Trees 78

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 109

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 181

American bur-reed3 ft · blooms indeterminate · medium shade tolerance · to −33 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °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 °FAmerican spongeplant0.5 ft · blooms mid spring · high shade tolerance · to −24 °F

Grasses 153

autumn bluegrass1.5 ft · blooms late spring · medium shade tolerance · to −8 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °FBailey's sedge2.1 ft · blooms late spring · low shade tolerance · to −33 °Fbig bluestem6 ft · blooms summer · high shade tolerance · to −46 °Fblister sedge3 ft · blooms late spring · medium shade tolerance · to −38 °Fbluejoint5 ft · blooms late spring · high shade tolerance · to −33 °F

Vines 14

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °FAmerican wisteria50 ft · blooms spring · low shade tolerance · to −3 °Fcatbird grape30 ft · blooms late spring · medium shade tolerance · to −13 °Fcupseed30 ft · blooms late spring · low shade tolerance · to −3 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Ffrost grape83 ft · blooms late spring · medium shade tolerance · to −23 °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 Smith Mills, KY.

Soil in Smith Mills, KY

The soil mapped at the center of ZIP 42457 is Melvin — slightly decomposed plant material, very poorly drained.

TextureSlightly decomposed plant materialtop layer
pH5.1strongly acidic; most vegetables like 6.0–7.0
DrainageVery poorly drainedconsider raised beds
Organic matter50%high
Hydrologic groupC/Dslow when drained; wet otherwise
Farmland classNot prime farmlandUSDA classification

Map unit: Melvin and Karnak soils, 0 to 1 percent slopes, ponded.

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 42457; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Smith Mills, KY

Summer high88 °Faverage high, July
Winter low23 °Faverage low, January
Hot days34days a year at 90 °F or more
Freezing nights86nights a year at 32 °F or less
Growing degree days4,094base 50 °F — the season’s usable heat
Longest day14 h 47 mindaylight on June 21
Shortest day9 h 32 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation46.6 inper year, rain and melted snow
Snowfall8 inper year

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 42 °F, low 23 °F 42°23° JanFebruary: average high 46 °F, low 26 °F 46°26° FebMarch: average high 56 °F, low 34 °F 56°34° MarApril: average high 67 °F, low 44 °F 67°44° AprMay: average high 77 °F, low 54 °F 77°54° MayJune: average high 85 °F, low 64 °F 85°64° JunJuly: average high 88 °F, low 67 °F 88°67° JulAugust: average high 87 °F, low 65 °F 87°65° AugSeptember: average high 82 °F, low 57 °F 82°57° SepOctober: average high 70 °F, low 45 °F 70°45° OctNovember: average high 57 °F, low 35 °F 57°35° NovDecember: average high 46 °F, low 27 °F 46°27° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″6″January: 3.53 in precipitation, 2.4 in snowfall 3.5❄2 JanFebruary: 2.93 in precipitation, 3.1 in snowfall 2.9❄3 FebMarch: 4.53 in precipitation, 1.5 in snowfall 4.5❄2 MarApril: 5.06 in precipitation 5.1 AprMay: 4.98 in precipitation 5.0 MayJune: 4.63 in precipitation 4.6 JunJuly: 3.64 in precipitation 3.6 JulAugust: 2.95 in precipitation 3.0 AugSeptember: 3.20 in precipitation 3.2 SepOctober: 3.49 in precipitation, 0.2 in snowfall 3.5 OctNovember: 3.89 in precipitation, 0.1 in snowfall 3.9 NovDecember: 3.79 in precipitation, 1.1 in snowfall 3.8❄1 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Mt Vernon, IN (9 mi away); precipitation: Mt Vernon, IN (9 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 7a.

424617a
Uniontown, KY · 6 mi
424627a
Waverly, KY · 6 mi
476207a
Mount Vernon, IN · 9 mi
477127a
Evansville, IN · 10 mi
424067a
Corydon, KY · 10 mi
424197a
Henderson, KY · 11 mi
477217a
Evansville, IN · 14 mi
424377a
Morganfield, KY · 14 mi

Kentucky planting zones →

Questions about 42457

What planting zone is ZIP code 42457?

ZIP code 42457 (Smith Mills, KY) is in USDA hardiness zone 7a on the 2023 map: the coldest night of an average winter reaches 0 to 5 °F (−17.8 to −15 °C).

When is the last frost in Smith Mills, KY?

The median last spring frost (32 °F) near 42457 is April 7; after April 27 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Mt Vernon station.

When is the first frost in Smith Mills, KY?

The median first fall frost near 42457 is October 28, giving a median frost-free growing season of 202 days.

When should I plant tomatoes in 42457?

Start tomato seeds indoors around Feb 10 – Feb 24 and set transplants outside around Apr 14 – Apr 28, one to three weeks after the median last frost.

How much rain and snow does 42457 get?

About 46.6 inches of precipitation a year and 8 inches of snowfall (NOAA 1991–2020 normals, Mt Vernon station).

How hot do summers get in Smith Mills, KY?

The average high peaks at 88 °F in July, with about 34 days a year at 90 °F or more.

What kind of soil does 42457 have?

The USDA soil survey maps Melvin at the center of ZIP 42457: slightly decomposed plant material, very poorly drained, pH about 5.1 (strongly acidic).

Did spring come early in Smith Mills, KY in 2026?

Spring leaf-out near 42457 came on Mar 2 in 2026, 8 days earlier than the 1991–2020 average (Mar 10), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Smith Mills, KY?

Intermediate onions: the longest day near 42457 is 14 h 47 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 42457 change?

Yes. The 2012 USDA map put 42457 in zone 6b; the 2023 map puts it in zone 7a. The newer map uses 1991–2020 data and more weather stations.