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

Planting zone for 46218 — Indianapolis, IN

ZIP code 46218 (Indianapolis, Marion County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is April 18 and the first fall frost October 26.

Where ZIP 46218 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 18
First frostOct 26
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 Indianapolis, 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 Indianapolis, IN

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 18median — 50% chance of a later frost
Safe for tender plantsMay 6only 10% chance of frost after
First fall frostOctober 26median — 10% chance by Oct 12
Growing season190 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 5 and returns around November 5.

From the NOAA station Castleton 2 S, IN — 6 miles away, elevation 824 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 46218

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 7 – Mar 21
SpinachSow outdoors · Mar 7 – Mar 28
Broccoli, cabbageStart indoors · Feb 7 – Feb 21
Broccoli, cabbageTransplant · Mar 28 – Apr 11
Onion setsPlant outdoors · Mar 21 – Apr 4
PotatoesPlant outdoors · Mar 28 – Apr 11
LettuceSow outdoors · Mar 21 – Apr 4
Carrots, beetsSow outdoors · Mar 28 – Apr 11
TomatoesStart indoors · Feb 21 – Mar 7
TomatoesTransplant · Apr 25 – May 9
Peppers, eggplantStart indoors · Feb 7 – Feb 21
Peppers, eggplantTransplant · May 2 – May 16
BeansSow outdoors · Apr 25 – May 9
Sweet cornSow outdoors · Apr 25 – May 9
Cucumbers, squashSow outdoors · Apr 25 – May 9
Fall lettuce, spinachSow outdoors · Aug 31 – Sep 14
GarlicPlant cloves · Oct 12 – Nov 16
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 18) and first fall frost (Oct 26) 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 46218 came on Mar 10 — 16 days earlier than the 1991–2020 average (Mar 26).

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.

Trees 71

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 105

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 200

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 161

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 9

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fcatbird grape30 ft · blooms late spring · medium shade tolerance · to −13 °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 °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 Indianapolis, IN.

Soil in Indianapolis, IN

The soil mapped at the center of ZIP 46218 is Brookston — silty clay loam, poorly drained.

TextureSilty clay loamholds water and nutrients; slow to drain and warm up
pH6.7neutral; most vegetables like 6.0–7.0
DrainagePoorly drainedconsider raised beds
Organic matter4%moderate
Hydrologic groupB/Dmoderate when drained; wet otherwise
Farmland classNot prime farmlandUSDA classification

Map unit: Brookston-Urban land complex, 0 to 2 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 46218; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Indianapolis, IN

Summer high85 °Faverage high, July
Winter low20 °Faverage low, January
Hot days19days a year at 90 °F or more
Freezing nights113nights a year at 32 °F or less
Growing degree days3,518base 50 °F — the season’s usable heat
Longest day15 h 00 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
Precipitation41.2 inper year, rain and melted snow

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 36 °F, low 20 °F 36°20° JanFebruary: average high 41 °F, low 23 °F 41°23° FebMarch: average high 51 °F, low 32 °F 51°32° MarApril: average high 64 °F, low 42 °F 64°42° AprMay: average high 74 °F, low 52 °F 74°52° MayJune: average high 82 °F, low 62 °F 82°62° JunJuly: average high 85 °F, low 65 °F 85°65° JulAugust: average high 83 °F, low 63 °F 83°63° AugSeptember: average high 77 °F, low 56 °F 77°56° SepOctober: average high 65 °F, low 45 °F 65°45° OctNovember: average high 52 °F, low 34 °F 52°34° NovDecember: average high 40 °F, low 25 °F 40°25° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 3.28 in precipitation 3.3 JanFebruary: 2.17 in precipitation 2.2 FebMarch: 3.37 in precipitation 3.4 MarApril: 3.83 in precipitation 3.8 AprMay: 4.41 in precipitation 4.4 MayJune: 4.99 in precipitation 5.0 JunJuly: 4.16 in precipitation 4.2 JulAugust: 2.62 in precipitation 2.6 AugSeptember: 3.12 in precipitation 3.1 SepOctober: 3.05 in precipitation 3.0 OctNovember: 3.35 in precipitation 3.4 NovDecember: 2.87 in precipitation 2.9 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Castleton 2 S, IN (6 mi away); precipitation: Indianapolis Zoo, IN (5 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

462016b
Indianapolis, IN · 2 mi
462056b
Indianapolis, IN · 2 mi
462096b
Indianapolis, IN · 3 mi
462306b
Indianapolis, IN · 3 mi
462426b
Indianapolis, IN · 3 mi
462446b
Indianapolis, IN · 3 mi
462476b
Indianapolis, IN · 3 mi
462516b
Indianapolis, IN · 3 mi

All 56 ZIP codes in Indianapolis → · Indiana planting zones →

Questions about 46218

What planting zone is ZIP code 46218?

ZIP code 46218 (Indianapolis, 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 Indianapolis, IN?

The median last spring frost (32 °F) near 46218 is April 18; after May 6 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Castleton 2 S station.

When is the first frost in Indianapolis, IN?

The median first fall frost near 46218 is October 26, giving a median frost-free growing season of 190 days.

When should I plant tomatoes in 46218?

Start tomato seeds indoors around Feb 21 – Mar 7 and set transplants outside around Apr 25 – May 9, one to three weeks after the median last frost.

How much rain and snow does 46218 get?

About 41.2 inches of precipitation a year (NOAA 1991–2020 normals, Indianapolis Zoo station).

How hot do summers get in Indianapolis, IN?

The average high peaks at 85 °F in July, with about 19 days a year at 90 °F or more.

What kind of soil does 46218 have?

The USDA soil survey maps Brookston at the center of ZIP 46218: silty clay loam, poorly drained, pH about 6.7 (neutral).

Did spring come early in Indianapolis, IN in 2026?

Spring leaf-out near 46218 came on Mar 10 in 2026, 16 days earlier than the 1991–2020 average (Mar 26), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Indianapolis, IN?

Intermediate onions: the longest day near 46218 is 15 h 00 min, so day-neutral types bulb best; long-day varieties may not bulb fully.