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

Planting zone for 46157 — Monrovia, IN

ZIP code 46157 (Monrovia, Morgan County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is April 24 and the first fall frost October 15.

Where ZIP 46157 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 24

First frostOct 15

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 Monrovia, 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 Monrovia, IN

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 24median — 50% chance of a later frost

Safe for tender plantsMay 11only 10% chance of frost after

First fall frostOctober 15median — 10% chance by Oct 2

Growing season173 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 12 and returns around October 26.

From the NOAA station Martinsville 2 Sw, IN — 11 miles away, elevation 591 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 46157

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 13 – Mar 27

SpinachSow outdoors · Mar 13 – Apr 3

Broccoli, cabbageStart indoors · Feb 13 – Feb 27

Broccoli, cabbageTransplant · Apr 3 – Apr 17

Onion setsPlant outdoors · Mar 27 – Apr 10

PotatoesPlant outdoors · Apr 3 – Apr 17

LettuceSow outdoors · Mar 27 – Apr 10

Carrots, beetsSow outdoors · Apr 3 – Apr 17

TomatoesStart indoors · Feb 27 – Mar 13

TomatoesTransplant · May 1 – May 15

Peppers, eggplantStart indoors · Feb 13 – Feb 27

Peppers, eggplantTransplant · May 8 – May 22

BeansSow outdoors · May 1 – May 15

Sweet cornSow outdoors · May 1 – May 15

Cucumbers, squashSow outdoors · May 1 – May 15

Fall lettuce, spinachSow outdoors · Aug 20 – Sep 3

GarlicPlant cloves · Oct 1 – Nov 5

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 24) and first fall frost (Oct 15) 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 46157 came on Mar 10 — 15 days earlier than the 1991–2020 average (Mar 25).

average
Mar 252026
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 6a in Indiana

558 plants native to the lower 48 states, recorded in Indiana, 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 Monrovia, IN.

Soil in Monrovia, IN

The soil mapped at the center of ZIP 46157 is Treaty — silty clay loam, poorly drained.

TextureSilty clay loamholds water and nutrients; slow to drain and warm up

pH6.5neutral; most vegetables like 6.0–7.0

DrainagePoorly drainedconsider raised beds

Organic matter4.5%moderate

Hydrologic groupB/Dmoderate when drained; wet otherwise

Farmland classPrime farmland if drainedUSDA classification

Map unit: Treaty silty clay loam, 0 to 1 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 46157; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Monrovia, IN

Summer high84 °Faverage high, July

Winter low19 °Faverage low, January

Hot days12days a year at 90 °F or more

Freezing nights127nights a year at 32 °F or less

Growing degree days3,244base 50 °F — the season’s usable heat

Longest day14 h 58 mindaylight on June 21

Shortest day9 h 22 mindaylight on December 21

Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully

Precipitation44.8 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: Martinsville 2 Sw, IN (11 mi away); precipitation: Clayton 0.4 Wnw, IN (9 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6a.

461806a

Stilesville, IN · 5 mi

Mooresville, IN · 8 mi

461116a

Brooklyn, IN · 9 mi

461516a

Martinsville, IN · 9 mi

Indiana planting zones →

Questions about 46157

What planting zone is ZIP code 46157?

ZIP code 46157 (Monrovia, 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 Monrovia, IN?

The median last spring frost (32 °F) near 46157 is April 24; after May 11 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Martinsville 2 Sw station.

When is the first frost in Monrovia, IN?

The median first fall frost near 46157 is October 15, giving a median frost-free growing season of 173 days.

When should I plant tomatoes in 46157?

Start tomato seeds indoors around Feb 27 – Mar 13 and set transplants outside around May 1 – May 15, one to three weeks after the median last frost.

How much rain and snow does 46157 get?

About 44.8 inches of precipitation a year (NOAA 1991–2020 normals, Clayton 0.4 Wnw station).

How hot do summers get in Monrovia, IN?

The average high peaks at 84 °F in July, with about 12 days a year at 90 °F or more.

What kind of soil does 46157 have?

The USDA soil survey maps Treaty at the center of ZIP 46157: silty clay loam, poorly drained, pH about 6.5 (neutral).

Did spring come early in Monrovia, IN in 2026?

Spring leaf-out near 46157 came on Mar 10 in 2026, 15 days earlier than the 1991–2020 average (Mar 25), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Monrovia, IN?

Intermediate onions: the longest day near 46157 is 14 h 58 min, so day-neutral types bulb best; long-day varieties may not bulb fully.