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

Planting zone for 61065 — Poplar Grove, IL

ZIP code 61065 (Poplar Grove, Boone County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is April 30 and the first fall frost October 10.

Where ZIP 61065 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.

Zone5b−15 to −10 °F
Coldest night−26.1 to −23.3 °C
Last frostApr 30
First frostOct 10
2012 zone5b

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 5b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Poplar Grove, 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 Poplar Grove, IL

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 30median — 50% chance of a later frost
Safe for tender plantsMay 17only 10% chance of frost after
First fall frostOctober 10median — 10% chance by Sep 26
Growing season161 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 19 and returns around October 20.

From the NOAA station Clinton Wwtp, WI — 11 miles away, elevation 925 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 61065

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 19 – Apr 2
SpinachSow outdoors · Mar 19 – Apr 9
Broccoli, cabbageStart indoors · Feb 19 – Mar 5
Broccoli, cabbageTransplant · Apr 9 – Apr 23
Onion setsPlant outdoors · Apr 2 – Apr 16
PotatoesPlant outdoors · Apr 9 – Apr 23
LettuceSow outdoors · Apr 2 – Apr 16
Carrots, beetsSow outdoors · Apr 9 – Apr 23
TomatoesStart indoors · Mar 5 – Mar 19
TomatoesTransplant · May 7 – May 21
Peppers, eggplantStart indoors · Feb 19 – Mar 5
Peppers, eggplantTransplant · May 14 – May 28
BeansSow outdoors · May 7 – May 21
Sweet cornSow outdoors · May 7 – May 21
Cucumbers, squashSow outdoors · May 7 – May 21
Fall lettuce, spinachSow outdoors · Aug 15 – Aug 29
GarlicPlant cloves · Sep 26 – Oct 31
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 30) and first fall frost (Oct 10) 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 61065 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 Poplar Grove, IL.

Soil in Poplar Grove, IL

The soil mapped at the center of ZIP 61065 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 61065; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Poplar Grove, IL

Summer high82 °Faverage high, July
Winter low10 °Faverage low, January
Hot days8days a year at 90 °F or more
Freezing nights148nights a year at 32 °F or less
Growing degree days2,687base 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)
Precipitation38.4 inper year, rain and melted snow

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 27 °F, low 10 °F 27°10° JanFebruary: average high 31 °F, low 15 °F 31°15° FebMarch: average high 44 °F, low 25 °F 44°25° MarApril: average high 57 °F, low 36 °F 57°36° AprMay: average high 69 °F, low 48 °F 69°48° MayJune: average high 78 °F, low 58 °F 78°58° JunJuly: average high 82 °F, low 61 °F 82°61° JulAugust: average high 80 °F, low 59 °F 80°59° AugSeptember: average high 74 °F, low 51 °F 74°51° SepOctober: average high 60 °F, low 39 °F 60°39° OctNovember: average high 45 °F, low 28 °F 45°28° NovDecember: average high 33 °F, low 17 °F 33°17° Dec

Precipitation by month inches

0″1″2″3″4″5″6″January: 1.69 in precipitation 1.7 JanFebruary: 1.71 in precipitation 1.7 FebMarch: 2.23 in precipitation 2.2 MarApril: 3.74 in precipitation 3.7 AprMay: 4.48 in precipitation 4.5 MayJune: 5.26 in precipitation 5.3 JunJuly: 3.93 in precipitation 3.9 JulAugust: 4.17 in precipitation 4.2 AugSeptember: 3.85 in precipitation 3.9 SepOctober: 2.99 in precipitation 3.0 OctNovember: 2.41 in precipitation 2.4 NovDecember: 1.94 in precipitation 1.9 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Clinton Wwtp, WI (11 mi away); precipitation: Capron 0.1 N, IL (5 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 5b.

610115b
Caledonia, IL · 3 mi
610125b
Capron, IL · 4 mi
610735b
Roscoe, IL · 8 mi
610805b
South Beloit, IL · 9 mi
611115b
Loves Park, IL · 10 mi
611155b
Machesney Park, IL · 10 mi
535255b
Clinton, WI · 10 mi
611145b
Rockford, IL · 10 mi

Illinois planting zones →

Questions about 61065

What planting zone is ZIP code 61065?

ZIP code 61065 (Poplar Grove, IL) is in USDA hardiness zone 5b on the 2023 map: the coldest night of an average winter reaches −15 to −10 °F (−26.1 to −23.3 °C).

When is the last frost in Poplar Grove, IL?

The median last spring frost (32 °F) near 61065 is April 30; after May 17 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Clinton Wwtp station.

When is the first frost in Poplar Grove, IL?

The median first fall frost near 61065 is October 10, giving a median frost-free growing season of 161 days.

When should I plant tomatoes in 61065?

Start tomato seeds indoors around Mar 5 – Mar 19 and set transplants outside around May 7 – May 21, one to three weeks after the median last frost.

How much rain and snow does 61065 get?

About 38.4 inches of precipitation a year (NOAA 1991–2020 normals, Capron 0.1 N station).

How hot do summers get in Poplar Grove, IL?

The average high peaks at 82 °F in July, with about 8 days a year at 90 °F or more.

What kind of soil does 61065 have?

The USDA soil survey maps Sable at the center of ZIP 61065: silty clay loam, poorly drained, pH about 6.0 (slightly acidic).

Did spring come early in Poplar Grove, IL in 2026?

Spring leaf-out near 61065 came on Mar 28 in 2026, 13 days earlier than the 1991–2020 average (Apr 10), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Poplar Grove, IL?

Long-day onions: the longest day near 61065 is 15 h 17 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).