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

Planting zone for 06085 — Unionville, CT

ZIP code 06085 (Unionville, Capitol Region County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is April 25 and the first fall frost October 18.

Where ZIP 06085 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.

Zone6b−5 to 0 °F

Coldest night−20.6 to −17.8 °C

Last frostApr 25

First frostOct 18

2012 zone6a

Was 6a 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 6b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Unionville, CT…

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 Unionville, CT

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 10only 10% chance of frost after

First fall frostOctober 18median — 10% chance by Oct 4

Growing season172 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 13 and returns around October 30.

From the NOAA station Burlington, CT — 4 miles away, elevation 505 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 06085

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 23 – Sep 6

GarlicPlant cloves · Oct 4 – Nov 8

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 25) and first fall frost (Oct 18) 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 06085 came on Apr 2 — 4 days earlier than the 1991–2020 average (Apr 6).

average
Apr 62026
Apr 2

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 6b in Connecticut

533 plants native to the lower 48 states, recorded in Connecticut, and rated by the USDA to survive −5 °F or colder — the bottom of zone 6b. 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 Unionville, CT.

Soil in Unionville, CT

The soil mapped at the center of ZIP 06085 is Hinckley — moderately decomposed plant material, excessively drained.

TextureModerately decomposed plant materialtop layer

DrainageExcessively drainednatural drainage class

Organic matter95%high

Hydrologic groupAwater soaks in fast

Farmland classFarmland of statewide importanceUSDA classification

Map unit: Hinckley loamy sand, 3 to 15 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 06085; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Unionville, CT

Summer high84 °Faverage high, July

Winter low17 °Faverage low, January

Hot days13days a year at 90 °F or more

Freezing nights142nights a year at 32 °F or less

Growing degree days2,830base 50 °F — the season’s usable heat

Longest day15 h 13 mindaylight on June 21

Shortest day9 h 08 mindaylight on December 21

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

Precipitation53.5 inper year, rain and melted snow

Snowfall39 inper year; 42 days with snow on the ground

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Burlington, CT (4 mi away); precipitation: Burlington, CT (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

1 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

060326b

Farmington, CT · 2 mi

060136a

Burlington, CT · 3 mi

Plainville, CT · 5 mi

060116b

Bristol, CT · 6 mi

060536b

New Britain, CT · 6 mi

061076b

West Hartford, CT · 7 mi

Connecticut planting zones →

Questions about 06085

What planting zone is ZIP code 06085?

ZIP code 06085 (Unionville, CT) is in USDA hardiness zone 6b on the 2023 map: the coldest night of an average winter reaches −5 to 0 °F (−20.6 to −17.8 °C).

When is the last frost in Unionville, CT?

The median last spring frost (32 °F) near 06085 is April 25; after May 10 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Burlington station.

When is the first frost in Unionville, CT?

The median first fall frost near 06085 is October 18, giving a median frost-free growing season of 172 days.

When should I plant tomatoes in 06085?

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 06085 get?

About 53.5 inches of precipitation a year and 39 inches of snowfall (NOAA 1991–2020 normals, Burlington station).

How hot do summers get in Unionville, CT?

The average high peaks at 84 °F in July, with about 13 days a year at 90 °F or more.

What kind of soil does 06085 have?

The USDA soil survey maps Hinckley at the center of ZIP 06085: moderately decomposed plant material, excessively drained.

Did spring come early in Unionville, CT in 2026?

Spring leaf-out near 06085 came on Apr 2 in 2026, 4 days earlier than the 1991–2020 average (Apr 6), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Unionville, CT?

Long-day onions: the longest day near 06085 is 15 h 13 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 06085 change?

Yes. The 2012 USDA map put 06085 in zone 6a; the 2023 map puts it in zone 6b. The newer map uses 1991–2020 data and more weather stations.