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

Planting zone for Mchenry, IL

Mchenry, IL is in USDA zone 5b across its 2 ZIP codes. The median last spring frost is May 1 and the first fall frost October 11.

Mchenry on the zone map

Outlined: its 2 ZIP code areas · 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.

Zone5b−15 to −10 °F
ZIP codes2
Last frostMay 1
First frostOct 11
Growing season162 days

5b 2 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Mchenry, 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 Mchenry, IL

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 1median — 50% chance of a later frost
Safe for tender plantsMay 19only 10% chance of frost after
First fall frostOctober 11median — 10% chance by Sep 27
Growing season162 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 19 and returns around October 22.

From the NOAA station Mc Henry -Wg Stratton L&D, IL, elevation 735 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 Mchenry

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 20 – Apr 3
SpinachSow outdoors · Mar 20 – Apr 10
Broccoli, cabbageStart indoors · Feb 20 – Mar 6
Broccoli, cabbageTransplant · Apr 10 – Apr 24
Onion setsPlant outdoors · Apr 3 – Apr 17
PotatoesPlant outdoors · Apr 10 – Apr 24
LettuceSow outdoors · Apr 3 – Apr 17
Carrots, beetsSow outdoors · Apr 10 – Apr 24
TomatoesStart indoors · Mar 6 – Mar 20
TomatoesTransplant · May 8 – May 22
Peppers, eggplantStart indoors · Feb 20 – Mar 6
Peppers, eggplantTransplant · May 15 – May 29
BeansSow outdoors · May 8 – May 22
Sweet cornSow outdoors · May 8 – May 22
Cucumbers, squashSow outdoors · May 8 – May 22
Fall lettuce, spinachSow outdoors · Aug 16 – Aug 30
GarlicPlant cloves · Sep 27 – Nov 1
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 1) and first fall frost (Oct 11) 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 60051 came on Mar 28 — 13 days earlier than the 1991–2020 average (Apr 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 5b in Illinois

584 plants native to the lower 48 states, recorded in Illinois, and rated by the USDA to survive −15 °F or colder — the bottom of zone 5b. Each links to its USDA PLANTS profile.

Trees 77

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 102

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 210

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °FAmerican 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 °F

Grasses 173

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 °FBailey's sedge2.1 ft · blooms late spring · low shade tolerance · to −33 °Fbeaked sedge4 ft · blooms late spring · low shade tolerance · to −38 °Fbeaked spikerush3 ft · blooms late spring · high shade tolerance · to −28 °F

Vines 7

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °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 °Ftrumpet honeysuckle16 ft · blooms late summer · low shade tolerance · to −33 °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 Mchenry, IL.

Soil in Mchenry, IL

The soil mapped at the center of ZIP 60051 is Casco — loam, somewhat excessively drained.

TextureLoama good balance for most vegetables
pH6.5neutral; most vegetables like 6.0–7.0
DrainageSomewhat excessively drainednatural drainage class
Organic matter2%moderate
Hydrologic groupBwater soaks in moderately
Farmland classNot prime farmlandUSDA classification

Map unit: Casco-Rodman complex, 20 to 30 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 60051; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Mchenry, IL

Summer high84 °Faverage high, July
Winter low13 °Faverage low, January
Hot days11days a year at 90 °F or more
Freezing nights144nights a year at 32 °F or less
Growing degree days2,891base 50 °F — the season’s usable heat
Longest day15 h 17 mindaylight on June 21
Shortest day9 h 04 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation37 inper year, rain and melted snow
Snowfall35 inper year; 55 days with snow on the ground

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 31 °F, low 13 °F 31°13° JanFebruary: average high 35 °F, low 16 °F 35°16° FebMarch: average high 46 °F, low 26 °F 46°26° MarApril: average high 59 °F, low 37 °F 59°37° AprMay: average high 70 °F, low 47 °F 70°47° MayJune: average high 80 °F, low 57 °F 80°57° JunJuly: average high 84 °F, low 62 °F 84°62° JulAugust: average high 82 °F, low 60 °F 82°60° AugSeptember: average high 76 °F, low 51 °F 76°51° SepOctober: average high 63 °F, low 40 °F 63°40° OctNovember: average high 48 °F, low 29 °F 48°29° NovDecember: average high 36 °F, low 19 °F 36°19° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″January: 1.65 in precipitation, 11 in snowfall 1.6❄11 JanFebruary: 1.56 in precipitation, 8.9 in snowfall 1.6❄9 FebMarch: 2.21 in precipitation, 3.9 in snowfall 2.2❄4 MarApril: 3.63 in precipitation, 1 in snowfall 3.6❄1 AprMay: 4.47 in precipitation 4.5 MayJune: 4.81 in precipitation 4.8 JunJuly: 3.80 in precipitation 3.8 JulAugust: 3.70 in precipitation 3.7 AugSeptember: 3.61 in precipitation 3.6 SepOctober: 3.21 in precipitation, 0.1 in snowfall 3.2 OctNovember: 2.38 in precipitation, 1.4 in snowfall 2.4❄1 NovDecember: 1.94 in precipitation, 8.2 in snowfall 1.9❄8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Mc Henry -Wg Stratton L&D, IL (3 mi away); precipitation: Mc Henry -Wg Stratton L&D, IL (3 mi away). Daylight is calculated from latitude.

ZIP codes in Mchenry

600505b
−15 to −10 °F
600515b
−15 to −10 °F

Illinois planting zones →

Questions about Mchenry

What planting zone is Mchenry, IL?

Mchenry, IL is in USDA hardiness zone 5b on the 2023 map (5b: −15 to −10 °F).

When is the last frost in Mchenry, IL?

The median last spring frost is May 1 and the median first fall frost is October 11 (NOAA 1991–2020 normals, Mc Henry -Wg Stratton L&D station).

When can I plant a garden in Mchenry, IL?

Cool-season crops like peas and spinach go in around Mar 20 – Apr 10; tomatoes, peppers, beans and squash after about May 8, once frost risk has passed.

What kind of onions grow in Mchenry, IL?

Long-day onions: the longest day is 15 h 17 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

How much rain and snow does Mchenry, IL get?

About 37 inches of precipitation a year and 35 inches of snowfall (NOAA 1991–2020 normals).