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

Planting zone for 61758 — Merna, IL

ZIP code 61758 (Merna, McLean County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is April 25 and the first fall frost October 16.

Where ZIP 61758 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.

Zone6a−10 to −5 °F

Coldest night−23.3 to −20.6 °C

Last frostApr 25

First frostOct 16

2012 zone5b

Was 5b 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 6a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Merna, 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 Merna, IL

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 25median — 50% chance of a later frost

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

First fall frostOctober 16median — 10% chance by Oct 2

Growing season172 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 14 and returns around October 27.

From the NOAA station Normal 4ne, IL — 7 miles away, elevation 791 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 61758

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 14 – Mar 28

SpinachSow outdoors · Mar 14 – Apr 4

Broccoli, cabbageStart indoors · Feb 14 – Feb 28

Broccoli, cabbageTransplant · Apr 4 – Apr 18

Onion setsPlant outdoors · Mar 28 – Apr 11

PotatoesPlant outdoors · Apr 4 – Apr 18

LettuceSow outdoors · Mar 28 – Apr 11

Carrots, beetsSow outdoors · Apr 4 – Apr 18

TomatoesStart indoors · Feb 28 – Mar 14

TomatoesTransplant · May 2 – May 16

Peppers, eggplantStart indoors · Feb 14 – Feb 28

Peppers, eggplantTransplant · May 9 – May 23

BeansSow outdoors · May 2 – May 16

Sweet cornSow outdoors · May 2 – May 16

Cucumbers, squashSow outdoors · May 2 – May 16

Fall lettuce, spinachSow outdoors · Aug 21 – Sep 4

GarlicPlant cloves · Oct 2 – Nov 6

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 25) and first fall frost (Oct 16) 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 61758 came on Mar 11 — 21 days earlier than the 1991–2020 average (Apr 1).

average
Apr 12026
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 Merna, IL.

Soil in Merna, IL

The soil mapped at the center of ZIP 61758 is Sable — silty clay loam, poorly drained.

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

pH6.0slightly acidic; 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: Sable silty clay 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 61758; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Merna, IL

Summer high86 °Faverage high, July

Winter low16 °Faverage low, January

Hot days26days a year at 90 °F or more

Freezing nights133nights a year at 32 °F or less

Growing degree days3,354base 50 °F — the season’s usable heat

Longest day15 h 04 mindaylight on June 21

Shortest day9 h 16 mindaylight on December 21

Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)

Precipitation40.5 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: Normal 4ne, IL (7 mi away); precipitation: Bloomington 2.7 Ne, IL (6 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6a.

617026a

Bloomington, IL · 2 mi

617916a

Bloomington, IL · 2 mi

617766a

Towanda, IL · 4 mi

617306a

Cooksville, IL · 5 mi

617996a

Bloomington, IL · 6 mi

Bloomington, IL · 7 mi

Illinois planting zones →

Questions about 61758

What planting zone is ZIP code 61758?

ZIP code 61758 (Merna, 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 Merna, IL?

The median last spring frost (32 °F) near 61758 is April 25; after May 11 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Normal 4ne station.

When is the first frost in Merna, IL?

The median first fall frost near 61758 is October 16, giving a median frost-free growing season of 172 days.

When should I plant tomatoes in 61758?

Start tomato seeds indoors around Feb 28 – Mar 14 and set transplants outside around May 2 – May 16, one to three weeks after the median last frost.

How much rain and snow does 61758 get?

About 40.5 inches of precipitation a year (NOAA 1991–2020 normals, Bloomington 2.7 Ne station).

How hot do summers get in Merna, IL?

The average high peaks at 86 °F in July, with about 26 days a year at 90 °F or more.

What kind of soil does 61758 have?

The USDA soil survey maps Sable at the center of ZIP 61758: silty clay loam, poorly drained, pH about 6.0 (slightly acidic).

Did spring come early in Merna, IL in 2026?

Spring leaf-out near 61758 came on Mar 11 in 2026, 21 days earlier than the 1991–2020 average (Apr 1), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Merna, IL?

Long-day onions: the longest day near 61758 is 15 h 04 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 61758 change?

Yes. The 2012 USDA map put 61758 in zone 5b; the 2023 map puts it in zone 6a. The newer map uses 1991–2020 data and more weather stations.