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

Planting zone for 46148 — Knightstown, IN

ZIP code 46148 (Knightstown, Henry County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is April 27 and the first fall frost October 17.

Where ZIP 46148 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 frostApr 27
First frostOct 17
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 Knightstown, 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 Knightstown, IN

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 27median — 50% chance of a later frost
Safe for tender plantsMay 12only 10% chance of frost after
First fall frostOctober 17median — 10% chance by Oct 4
Growing season173 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 15 and returns around October 27.

From the NOAA station New Castle 3 Sw, IN — 9 miles away, elevation 991 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 46148

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 16 – Mar 30
SpinachSow outdoors · Mar 16 – Apr 6
Broccoli, cabbageStart indoors · Feb 16 – Mar 2
Broccoli, cabbageTransplant · Apr 6 – Apr 20
Onion setsPlant outdoors · Mar 30 – Apr 13
PotatoesPlant outdoors · Apr 6 – Apr 20
LettuceSow outdoors · Mar 30 – Apr 13
Carrots, beetsSow outdoors · Apr 6 – Apr 20
TomatoesStart indoors · Mar 2 – Mar 16
TomatoesTransplant · May 4 – May 18
Peppers, eggplantStart indoors · Feb 16 – Mar 2
Peppers, eggplantTransplant · May 11 – May 25
BeansSow outdoors · May 4 – May 18
Sweet cornSow outdoors · May 4 – May 18
Cucumbers, squashSow outdoors · May 4 – May 18
Fall lettuce, spinachSow outdoors · Aug 22 – Sep 5
GarlicPlant cloves · Oct 3 – Nov 7
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 27) and first fall frost (Oct 17) 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 46148 came on Mar 10 — 19 days earlier than the 1991–2020 average (Mar 29).

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).

Soil in Knightstown, IN

The soil mapped at the center of ZIP 46148 is Miamian — silt loam, well drained.

TextureSilt loama good balance for most vegetables
pH6.5neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2.5%moderate
Hydrologic groupCwater soaks in slowly
Farmland classprime farmlandUSDA classification

Map unit: Miamian silt loam, New Castle Till Plain, 2 to 6 percent slopes, eroded.

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 46148; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Knightstown, IN

Summer high83 °Faverage high, July
Winter low17 °Faverage low, January
Hot days9days a year at 90 °F or more
Freezing nights132nights a year at 32 °F or less
Growing degree days3,058base 50 °F — the season’s usable heat
Longest day14 h 59 mindaylight on June 21
Shortest day9 h 21 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation47.1 inper year, rain and melted snow
Snowfall29 inper year

Average high and low, by month

10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 34 °F, low 17 °F 34°17° JanFebruary: average high 38 °F, low 19 °F 38°19° FebMarch: average high 49 °F, low 28 °F 49°28° MarApril: average high 62 °F, low 38 °F 62°38° AprMay: average high 72 °F, low 50 °F 72°50° MayJune: average high 80 °F, low 59 °F 80°59° JunJuly: average high 83 °F, low 61 °F 83°61° JulAugust: average high 82 °F, low 59 °F 82°59° AugSeptember: average high 77 °F, low 52 °F 77°52° SepOctober: average high 65 °F, low 41 °F 65°41° OctNovember: average high 51 °F, low 31 °F 51°31° NovDecember: average high 39 °F, low 23 °F 39°23° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″6″January: 3.67 in precipitation, 10.1 in snowfall 3.7❄10 JanFebruary: 2.61 in precipitation, 7.4 in snowfall 2.6❄7 FebMarch: 3.75 in precipitation, 3.5 in snowfall 3.8❄4 MarApril: 4.81 in precipitation, 0.2 in snowfall 4.8 AprMay: 5.28 in precipitation 5.3 MayJune: 5.36 in precipitation 5.4 JunJuly: 4.59 in precipitation 4.6 JulAugust: 3.66 in precipitation 3.7 AugSeptember: 3.20 in precipitation 3.2 SepOctober: 3.36 in precipitation, 0.1 in snowfall 3.4 OctNovember: 3.64 in precipitation, 0.8 in snowfall 3.6❄1 NovDecember: 3.14 in precipitation, 6.5 in snowfall 3.1❄7 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: New Castle 3 Sw, IN (9 mi away); precipitation: Knightstown 2ene, IN (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6a.

473376a
Dunreith, IN · 3 mi
473856a
Spiceland, IN · 4 mi
461156a
Carthage, IN · 6 mi
473526a
Lewisville, IN · 6 mi
473446a
Greensboro, IN · 7 mi
461176a
Charlottesville, IN · 8 mi
461276a
Falmouth, IN · 9 mi
473846a
Shirley, IN · 10 mi

Indiana planting zones →

Questions about 46148

What planting zone is ZIP code 46148?

ZIP code 46148 (Knightstown, IN) 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 Knightstown, IN?

The median last spring frost (32 °F) near 46148 is April 27; after May 12 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, New Castle 3 Sw station.

When is the first frost in Knightstown, IN?

The median first fall frost near 46148 is October 17, giving a median frost-free growing season of 173 days.

When should I plant tomatoes in 46148?

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

How much rain and snow does 46148 get?

About 47.1 inches of precipitation a year and 29 inches of snowfall (NOAA 1991–2020 normals, Knightstown 2ene station).

How hot do summers get in Knightstown, IN?

The average high peaks at 83 °F in July, with about 9 days a year at 90 °F or more.

What kind of soil does 46148 have?

The USDA soil survey maps Miamian at the center of ZIP 46148: silt loam, well drained, pH about 6.5 (neutral).

Did spring come early in Knightstown, IN in 2026?

Spring leaf-out near 46148 came on Mar 10 in 2026, 19 days earlier than the 1991–2020 average (Mar 29), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Knightstown, IN?

Intermediate onions: the longest day near 46148 is 14 h 59 min, so day-neutral types bulb best; long-day varieties may not bulb fully.