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

Planting zone for Suffield, CT

Suffield, CT is in USDA zone 6b across its 2 ZIP codes. The median last spring frost is April 21 and the first fall frost October 16.

Suffield 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.

Zone6b−5 to 0 °F
ZIP codes2
Last frostApr 21
First frostOct 16
Growing season177 days

6b 2 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Suffield, 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 Suffield, CT

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 21median — 50% chance of a later frost
Safe for tender plantsMay 6only 10% chance of frost after
First fall frostOctober 16median — 10% chance by Oct 3
Growing season177 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 7 and returns around October 29.

From the NOAA station Hartford Bradley Intl Airport, CT, elevation 190 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 Suffield

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 10 – Mar 24
SpinachSow outdoors · Mar 10 – Mar 31
Broccoli, cabbageStart indoors · Feb 10 – Feb 24
Broccoli, cabbageTransplant · Mar 31 – Apr 14
Onion setsPlant outdoors · Mar 24 – Apr 7
PotatoesPlant outdoors · Mar 31 – Apr 14
LettuceSow outdoors · Mar 24 – Apr 7
Carrots, beetsSow outdoors · Mar 31 – Apr 14
TomatoesStart indoors · Feb 24 – Mar 10
TomatoesTransplant · Apr 28 – May 12
Peppers, eggplantStart indoors · Feb 10 – Feb 24
Peppers, eggplantTransplant · May 5 – May 19
BeansSow outdoors · Apr 28 – May 12
Sweet cornSow outdoors · Apr 28 – May 12
Cucumbers, squashSow outdoors · Apr 28 – May 12
Fall lettuce, spinachSow outdoors · Aug 21 – Sep 4
GarlicPlant cloves · Oct 2 – Nov 6
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 21) and first fall frost (Oct 16) 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 06078 came on Apr 2 — 4 days earlier than the 1991–2020 average (Apr 6).

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 Suffield, CT.

Soil in Suffield, CT

The soil mapped at the center of ZIP 06078 is Wethersfield — loam, well drained.

TextureLoama good balance for most vegetables
pH5.3strongly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter3.5%moderate
Hydrologic groupCwater soaks in slowly
Farmland classFarmland of statewide importanceUSDA classification

Map unit: Wethersfield loam, 8 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 06078; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Suffield, CT

Summer high85 °Faverage high, July
Winter low19 °Faverage low, January
Hot days20days a year at 90 °F or more
Freezing nights126nights a year at 32 °F or less
Growing degree days3,069base 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)
Precipitation47 inper year, rain and melted snow
Snowfall52 inper year

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 39 °F, low 21 °F 39°21° FebMarch: average high 47 °F, low 28 °F 47°28° MarApril: average high 61 °F, low 38 °F 61°38° AprMay: average high 72 °F, low 48 °F 72°48° MayJune: average high 80 °F, low 58 °F 80°58° JunJuly: average high 85 °F, low 63 °F 85°63° JulAugust: average high 83 °F, low 62 °F 83°62° AugSeptember: average high 76 °F, low 54 °F 76°54° SepOctober: average high 64 °F, low 42 °F 64°42° OctNovember: average high 52 °F, low 33 °F 52°33° NovDecember: average high 41 °F, low 25 °F 41°25° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″January: 3.28 in precipitation, 14.2 in snowfall 3.3❄14 JanFebruary: 3.13 in precipitation, 14.8 in snowfall 3.1❄15 FebMarch: 3.81 in precipitation, 9.4 in snowfall 3.8❄9 MarApril: 3.88 in precipitation, 1.1 in snowfall 3.9❄1 AprMay: 3.79 in precipitation 3.8 MayJune: 4.28 in precipitation 4.3 JunJuly: 4.17 in precipitation 4.2 JulAugust: 4.21 in precipitation 4.2 AugSeptember: 4.39 in precipitation 4.4 SepOctober: 4.52 in precipitation, 0.7 in snowfall 4.5❄1 OctNovember: 3.51 in precipitation, 1.4 in snowfall 3.5❄1 NovDecember: 4.08 in precipitation, 10.1 in snowfall 4.1❄10 Dec

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

ZIP codes in Suffield

060786b
−5 to 0 °F
060806b
−5 to 0 °F

Connecticut planting zones →

Questions about Suffield

What planting zone is Suffield, CT?

Suffield, CT is in USDA hardiness zone 6b on the 2023 map (6b: −5 to 0 °F).

When is the last frost in Suffield, CT?

The median last spring frost is April 21 and the median first fall frost is October 16 (NOAA 1991–2020 normals, Hartford Bradley Intl Airport station).

When can I plant a garden in Suffield, CT?

Cool-season crops like peas and spinach go in around Mar 10 – Mar 31; tomatoes, peppers, beans and squash after about Apr 28, once frost risk has passed.

What kind of onions grow in Suffield, CT?

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

How much rain and snow does Suffield, CT get?

About 47 inches of precipitation a year and 52 inches of snowfall (NOAA 1991–2020 normals).