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

Planting zone for 06255 — North Grosvenordale, CT

ZIP code 06255 (North Grosvenordale, Windham County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is May 1 and the first fall frost October 9.

Where ZIP 06255 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.

Zone6a−10 to −5 °F
Coldest night−23.3 to −20.6 °C
Last frostMay 1
First frostOct 9
2012 zone6a

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 6a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for North Grosvenordale, 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 North Grosvenordale, CT

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 17only 10% chance of frost after
First fall frostOctober 9median — 10% chance by Sep 30
Growing season161 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 19 and returns around October 21.

From the NOAA station W Thompson Lake, CT — 3 miles away, elevation 361 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 06255

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 14 – Aug 28
GarlicPlant cloves · Sep 25 – Oct 30
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 1) and first fall frost (Oct 9) 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 06255 came on Apr 3 — 8 days earlier than the 1991–2020 average (Apr 11).

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 Connecticut

528 plants native to the lower 48 states, recorded in Connecticut, and rated by the USDA to survive −10 °F or colder — the bottom of zone 6a. 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 185

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 149

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 spikerush3 ft · blooms late spring · high shade tolerance · to −28 °FBebb's sedge3 ft · blooms late spring · low shade tolerance · to −38 °F

Vines 8

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 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Fsummer grape30 ft · blooms late spring · low shade tolerance · to −23 °Ftrumpet creeper2 ft · blooms summer · high shade tolerance · to −13 °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 North Grosvenordale, CT.

Soil in North Grosvenordale, CT

The soil mapped at the center of ZIP 06255 is Ridgebury — moderately decomposed plant material, poorly drained.

TextureModerately decomposed plant materialtop layer
DrainagePoorly drainedconsider raised beds
Organic matter95%high
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Ridgebury, Leicester, and Whitman soils, 0 to 8 percent slopes, extremely 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 06255; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in North Grosvenordale, CT

Summer high82 °Faverage high, July
Winter low15 °Faverage low, January
Hot days8days a year at 90 °F or more
Freezing nights156nights a year at 32 °F or less
Growing degree days2,489base 50 °F — the season’s usable heat
Longest day15 h 14 mindaylight on June 21
Shortest day9 h 07 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation50.1 inper year, rain and melted snow
Snowfall39 inper year; 44 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 35 °F, low 15 °F 35°15° JanFebruary: average high 38 °F, low 17 °F 38°17° FebMarch: average high 46 °F, low 24 °F 46°24° MarApril: average high 58 °F, low 34 °F 58°34° AprMay: average high 69 °F, low 45 °F 69°45° MayJune: average high 76 °F, low 54 °F 76°54° JunJuly: average high 82 °F, low 60 °F 82°60° JulAugust: average high 80 °F, low 58 °F 80°58° AugSeptember: average high 73 °F, low 51 °F 73°51° SepOctober: average high 61 °F, low 38 °F 61°38° OctNovember: average high 50 °F, low 30 °F 50°30° NovDecember: average high 40 °F, low 22 °F 40°22° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″January: 3.78 in precipitation, 10.6 in snowfall 3.8❄11 JanFebruary: 3.53 in precipitation, 11.6 in snowfall 3.5❄12 FebMarch: 4.45 in precipitation, 7.2 in snowfall 4.5❄7 MarApril: 4.57 in precipitation, 1.5 in snowfall 4.6❄2 AprMay: 3.43 in precipitation 3.4 MayJune: 4.48 in precipitation 4.5 JunJuly: 4.02 in precipitation 4.0 JulAugust: 4.24 in precipitation 4.2 AugSeptember: 3.91 in precipitation 3.9 SepOctober: 4.77 in precipitation, 0.2 in snowfall 4.8 OctNovember: 4.18 in precipitation, 0.9 in snowfall 4.2❄1 NovDecember: 4.72 in precipitation, 6.5 in snowfall 4.7❄7 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: W Thompson Lake, CT (3 mi away); precipitation: W Thompson Lake, CT (3 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

062466a
Grosvenor Dale, CT · 1 mi
062456a
Fabyan, CT · 3 mi
062626a
Quinebaug, CT · 3 mi
062776b
Thompson, CT · 4 mi
062676b
South Woodstock, CT · 4 mi
062446a
East Woodstock, CT · 4 mi
015716b
Dudley, MA · 5 mi
015706b
Webster, MA · 5 mi

Connecticut planting zones →

Questions about 06255

What planting zone is ZIP code 06255?

ZIP code 06255 (North Grosvenordale, CT) is in USDA hardiness zone 6a on the 2023 map: the coldest night of an average winter reaches −10 to −5 °F (−23.3 to −20.6 °C).

When is the last frost in North Grosvenordale, CT?

The median last spring frost (32 °F) near 06255 is May 1; after May 17 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, W Thompson Lake station.

When is the first frost in North Grosvenordale, CT?

The median first fall frost near 06255 is October 9, giving a median frost-free growing season of 161 days.

When should I plant tomatoes in 06255?

Start tomato seeds indoors around Mar 6 – Mar 20 and set transplants outside around May 8 – May 22, one to three weeks after the median last frost.

How much rain and snow does 06255 get?

About 50.1 inches of precipitation a year and 39 inches of snowfall (NOAA 1991–2020 normals, W Thompson Lake station).

How hot do summers get in North Grosvenordale, CT?

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 06255 have?

The USDA soil survey maps Ridgebury at the center of ZIP 06255: moderately decomposed plant material, poorly drained.

Did spring come early in North Grosvenordale, CT in 2026?

Spring leaf-out near 06255 came on Apr 3 in 2026, 8 days earlier than the 1991–2020 average (Apr 11), according to the USA National Phenology Network Spring Index.

What kind of onions grow in North Grosvenordale, CT?

Long-day onions: the longest day near 06255 is 15 h 14 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).