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

Planting zone for 06331 — Canterbury, CT

ZIP code 06331 (Canterbury, Northeastern Connecticut County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is April 30 and the first fall frost October 15.

Where ZIP 06331 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 30
First frostOct 15
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 Canterbury, 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 Canterbury, CT

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 11only 10% chance of frost after
First fall frostOctober 15median — 10% chance by Oct 1
Growing season167 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 16 and returns around October 28.

From the NOAA station Hampton, CT — 6 miles away, elevation 489 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 06331

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 20 – Sep 3
GarlicPlant cloves · Oct 1 – Nov 5
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 30) and first fall frost (Oct 15) 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 06331 came on Apr 3 — 4 days earlier than the 1991–2020 average (Apr 7).

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.

Trees 64

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 105

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 187

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 151

American beachgrass2.5 ft · blooms spring · high shade tolerance · to −28 °Farctic brome3 ft · blooms early summer · low shade tolerance · to −33 °FAtlantic mannagrass3 ft · blooms summer · low shade tolerance · to −8 °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 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 °Fheartleaf peppervine2 ft · blooms late spring · low shade tolerance · to −8 °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 Canterbury, CT.

Soil in Canterbury, CT

The soil mapped at the center of ZIP 06331 is Woodbridge — moderately decomposed plant material, moderately well drained.

TextureModerately decomposed plant materialtop layer
DrainageModerately well drainednatural drainage class
Organic matter95%high
Hydrologic groupC/Dslow when drained; wet otherwise
Farmland classFarmland of statewide importanceUSDA classification

Map unit: Woodbridge fine sandy loam, 0 to 8 percent slopes, very stony.

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 06331; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Canterbury, CT

Summer high80 °Faverage high, July
Winter low17 °Faverage low, January
Hot days3days a year at 90 °F or more
Freezing nights142nights a year at 32 °F or less
Growing degree days2,427base 50 °F — the season’s usable heat
Longest day15 h 12 mindaylight on June 21
Shortest day9 h 09 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation50.6 inper year, rain and melted snow

Average high and low, by month

10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 36 °F, low 17 °F 36°17° JanFebruary: average high 38 °F, low 18 °F 38°18° FebMarch: average high 46 °F, low 25 °F 46°25° MarApril: average high 58 °F, low 35 °F 58°35° AprMay: average high 68 °F, low 45 °F 68°45° MayJune: average high 75 °F, low 54 °F 75°54° JunJuly: average high 80 °F, low 60 °F 80°60° JulAugust: average high 79 °F, low 58 °F 79°58° AugSeptember: average high 73 °F, low 51 °F 73°51° SepOctober: average high 62 °F, low 40 °F 62°40° OctNovember: average high 51 °F, low 31 °F 51°31° NovDecember: average high 41 °F, low 23 °F 41°23° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 4.05 in precipitation 4.0 JanFebruary: 3.37 in precipitation 3.4 FebMarch: 4.44 in precipitation 4.4 MarApril: 4.67 in precipitation 4.7 AprMay: 3.74 in precipitation 3.7 MayJune: 4.32 in precipitation 4.3 JunJuly: 3.91 in precipitation 3.9 JulAugust: 4.21 in precipitation 4.2 AugSeptember: 4.31 in precipitation 4.3 SepOctober: 4.73 in precipitation 4.7 OctNovember: 4.11 in precipitation 4.1 NovDecember: 4.78 in precipitation 4.8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Hampton, CT (6 mi away); precipitation: Hampton, CT (6 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6b.

063506b
Hanover, CT · 4 mi
062646b
Scotland, CT · 5 mi
063746b
Plainfield, CT · 5 mi
063306b
Baltic, CT · 5 mi
063326b
Central Village, CT · 6 mi
062476b
Hampton, CT · 6 mi
063876b
Wauregan, CT · 6 mi
062806b
Windham, CT · 6 mi

Connecticut planting zones →

Questions about 06331

What planting zone is ZIP code 06331?

ZIP code 06331 (Canterbury, 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 Canterbury, CT?

The median last spring frost (32 °F) near 06331 is April 30; after May 11 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Hampton station.

When is the first frost in Canterbury, CT?

The median first fall frost near 06331 is October 15, giving a median frost-free growing season of 167 days.

When should I plant tomatoes in 06331?

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 06331 get?

About 50.6 inches of precipitation a year (NOAA 1991–2020 normals, Hampton station).

How hot do summers get in Canterbury, CT?

The average high peaks at 80 °F in July, with about 3 days a year at 90 °F or more.

What kind of soil does 06331 have?

The USDA soil survey maps Woodbridge at the center of ZIP 06331: moderately decomposed plant material, moderately well drained.

Did spring come early in Canterbury, CT in 2026?

Spring leaf-out near 06331 came on Apr 3 in 2026, 4 days earlier than the 1991–2020 average (Apr 7), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Canterbury, CT?

Long-day onions: the longest day near 06331 is 15 h 12 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 06331 change?

Yes. The 2012 USDA map put 06331 in zone 6a; the 2023 map puts it in zone 6b. The newer map uses 1991–2020 data and more weather stations.