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

Planting zone for 62551 — Niantic, IL

ZIP code 62551 (Niantic, Macon County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is April 14 and the first fall frost October 24.

Where ZIP 62551 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 14

First frostOct 24

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 Niantic, IL…

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 Niantic, IL

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 14median — 50% chance of a later frost

Safe for tender plantsMay 1only 10% chance of frost after

First fall frostOctober 24median — 10% chance by Oct 11

Growing season192 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 3 and returns around November 3.

From the NOAA station Decatur Wtp, IL — 11 miles away, elevation 640 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 62551

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 3 – Mar 17

SpinachSow outdoors · Mar 3 – Mar 24

Broccoli, cabbageStart indoors · Feb 3 – Feb 17

Broccoli, cabbageTransplant · Mar 24 – Apr 7

Onion setsPlant outdoors · Mar 17 – Mar 31

PotatoesPlant outdoors · Mar 24 – Apr 7

LettuceSow outdoors · Mar 17 – Mar 31

Carrots, beetsSow outdoors · Mar 24 – Apr 7

TomatoesStart indoors · Feb 17 – Mar 3

TomatoesTransplant · Apr 21 – May 5

Peppers, eggplantStart indoors · Feb 3 – Feb 17

Peppers, eggplantTransplant · Apr 28 – May 12

BeansSow outdoors · Apr 21 – May 5

Sweet cornSow outdoors · Apr 21 – May 5

Cucumbers, squashSow outdoors · Apr 21 – May 5

Fall lettuce, spinachSow outdoors · Aug 29 – Sep 12

GarlicPlant cloves · Oct 10 – Nov 14

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 14) and first fall frost (Oct 24) 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 62551 came on Mar 11 — 14 days earlier than the 1991–2020 average (Mar 25).

average
Mar 252026
Mar 11

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 Illinois

610 plants native to the lower 48 states, recorded in Illinois, 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 Niantic, IL.

Soil in Niantic, IL

The soil mapped at the center of ZIP 62551 is Plano — silt loam, well drained.

TextureSilt loama good balance for most vegetables

pH6.7neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter3.5%moderate

Hydrologic groupBwater soaks in moderately

Farmland classprime farmlandUSDA classification

Map unit: Plano silt loam, 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 62551; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Niantic, IL

Summer high85 °Faverage high, July

Winter low20 °Faverage low, January

Hot days26days a year at 90 °F or more

Freezing nights110nights a year at 32 °F or less

Growing degree days3,664base 50 °F — the season’s usable heat

Longest day15 h 00 mindaylight on June 21

Shortest day9 h 20 mindaylight on December 21

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

Precipitation40.4 inper year, rain and melted snow

Snowfall14 inper year

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Decatur Wtp, IL (11 mi away); precipitation: Decatur Wtp, IL (11 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6a.

625376a

Harristown, IL · 3 mi

625396a

Illiopolis, IL · 5 mi

625226a

Decatur, IL · 6 mi

625476a

Mount Auburn, IL · 7 mi

625736a

Warrensburg, IL · 8 mi

Blue Mound, IL · 9 mi

Illinois planting zones →

Questions about 62551

What planting zone is ZIP code 62551?

ZIP code 62551 (Niantic, IL) 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 Niantic, IL?

The median last spring frost (32 °F) near 62551 is April 14; after May 1 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Decatur Wtp station.

When is the first frost in Niantic, IL?

The median first fall frost near 62551 is October 24, giving a median frost-free growing season of 192 days.

When should I plant tomatoes in 62551?

Start tomato seeds indoors around Feb 17 – Mar 3 and set transplants outside around Apr 21 – May 5, one to three weeks after the median last frost.

How much rain and snow does 62551 get?

About 40.4 inches of precipitation a year and 14 inches of snowfall (NOAA 1991–2020 normals, Decatur Wtp station).

How hot do summers get in Niantic, IL?

The average high peaks at 85 °F in July, with about 26 days a year at 90 °F or more.

What kind of soil does 62551 have?

The USDA soil survey maps Plano at the center of ZIP 62551: silt loam, well drained, pH about 6.7 (neutral).

Did spring come early in Niantic, IL in 2026?

Spring leaf-out near 62551 came on Mar 11 in 2026, 14 days earlier than the 1991–2020 average (Mar 25), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Niantic, IL?

Intermediate onions: the longest day near 62551 is 15 h 00 min, so day-neutral types bulb best; long-day varieties may not bulb fully.