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

Planting zone for Quincy, IL

Quincy, IL is in USDA zone 6a across its 3 ZIP codes. The median last spring frost is April 8 and the first fall frost October 30.

Quincy 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.

Zone6a−10 to −5 °F
ZIP codes3
Last frostApr 8
First frostOct 30
Growing season204 days

6a 3 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

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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 Quincy, IL

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 8median — 50% chance of a later frost
Safe for tender plantsApril 23only 10% chance of frost after
First fall frostOctober 30median — 10% chance by Oct 17
Growing season204 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 30 and returns around November 8.

From the NOAA station Quincy Dam 21, IL, elevation 482 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 Quincy

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 25 – Mar 11
SpinachSow outdoors · Feb 25 – Mar 18
Broccoli, cabbageStart indoors · Jan 28 – Feb 11
Broccoli, cabbageTransplant · Mar 18 – Apr 1
Onion setsPlant outdoors · Mar 11 – Mar 25
PotatoesPlant outdoors · Mar 18 – Apr 1
LettuceSow outdoors · Mar 11 – Mar 25
Carrots, beetsSow outdoors · Mar 18 – Apr 1
TomatoesStart indoors · Feb 11 – Feb 25
TomatoesTransplant · Apr 15 – Apr 29
Peppers, eggplantStart indoors · Jan 28 – Feb 11
Peppers, eggplantTransplant · Apr 22 – May 6
BeansSow outdoors · Apr 15 – Apr 29
Sweet cornSow outdoors · Apr 15 – Apr 29
Cucumbers, squashSow outdoors · Apr 15 – Apr 29
Fall lettuce, spinachSow outdoors · Sep 4 – Sep 18
GarlicPlant cloves · Oct 16 – Nov 20
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 8) and first fall frost (Oct 30) 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 62301 came on Mar 10 — 13 days earlier than the 1991–2020 average (Mar 23).

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.

Trees 78

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 108

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 220

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 178

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 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 Quincy, IL.

Soil in Quincy, IL

The soil mapped at the center of ZIP 62301 is Biggsville — silt loam, well drained.

TextureSilt loama good balance for most vegetables
pH6.8neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter4%moderate
Hydrologic groupBwater soaks in moderately
Farmland classprime farmlandUSDA classification

Map unit: Biggsville-Mannon silt loams, 1 to 7 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 62301; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Quincy, IL

Summer high87 °Faverage high, July
Winter low19 °Faverage low, January
Hot days31days a year at 90 °F or more
Freezing nights112nights a year at 32 °F or less
Growing degree days3,861base 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 growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation36.5 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 35 °F, low 19 °F 35°19° JanFebruary: average high 40 °F, low 23 °F 40°23° FebMarch: average high 52 °F, low 32 °F 52°32° MarApril: average high 64 °F, low 43 °F 64°43° AprMay: average high 74 °F, low 54 °F 74°54° MayJune: average high 83 °F, low 64 °F 83°64° JunJuly: average high 87 °F, low 68 °F 87°68° JulAugust: average high 86 °F, low 66 °F 86°66° AugSeptember: average high 79 °F, low 57 °F 79°57° SepOctober: average high 67 °F, low 45 °F 67°45° OctNovember: average high 53 °F, low 34 °F 53°34° NovDecember: average high 40 °F, low 25 °F 40°25° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 1.66 in precipitation 1.7 JanFebruary: 1.91 in precipitation 1.9 FebMarch: 2.48 in precipitation 2.5 MarApril: 4.22 in precipitation 4.2 AprMay: 4.80 in precipitation 4.8 MayJune: 4.12 in precipitation 4.1 JunJuly: 3.64 in precipitation 3.6 JulAugust: 3.33 in precipitation 3.3 AugSeptember: 3.37 in precipitation 3.4 SepOctober: 2.65 in precipitation 2.6 OctNovember: 2.57 in precipitation 2.6 NovDecember: 1.73 in precipitation 1.7 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Quincy Dam 21, IL (3 mi away); precipitation: Quincy Dam 21, IL (3 mi away). Daylight is calculated from latitude.

ZIP codes in Quincy

623016a
−10 to −5 °F
623056a
−10 to −5 °F
623066a
−10 to −5 °F

Illinois planting zones →

Questions about Quincy

What planting zone is Quincy, IL?

Quincy, IL is in USDA hardiness zone 6a on the 2023 map (6a: −10 to −5 °F).

When is the last frost in Quincy, IL?

The median last spring frost is April 8 and the median first fall frost is October 30 (NOAA 1991–2020 normals, Quincy Dam 21 station).

When can I plant a garden in Quincy, IL?

Cool-season crops like peas and spinach go in around Feb 25 – Mar 18; tomatoes, peppers, beans and squash after about Apr 15, once frost risk has passed.

What kind of onions grow in Quincy, IL?

Long-day onions: the longest day is 15 h 00 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

How much rain and snow does Quincy, IL get?

About 36.5 inches of precipitation a year (NOAA 1991–2020 normals).