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

Planting zone for 06420 — Salem, CT

ZIP code 06420 (Salem, Southeastern Connecticut County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is April 14 and the first fall frost October 24.

Where ZIP 06420 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 14
First frostOct 24
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 Salem, 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 Salem, CT

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 14median — 50% chance of a later frost
Safe for tender plantsApril 30only 10% chance of frost after
First fall frostOctober 24median — 10% chance by Oct 9
Growing season192 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 1 and returns around November 5.

From the NOAA station Norwich Public Utility Plt, CT — 11 miles away, elevation 20 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 06420

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 3 – Mar 17
SpinachSow outdoors · Mar 3 – Mar 24
Broccoli, cabbageStart indoors · Feb 3 – Feb 17
Broccoli, cabbageTransplant · Mar 24 – Apr 7
Onion setsPlant outdoors · Mar 17 – Mar 31
PotatoesPlant outdoors · Mar 24 – Apr 7
LettuceSow outdoors · Mar 17 – Mar 31
Carrots, beetsSow outdoors · Mar 24 – Apr 7
TomatoesStart indoors · Feb 17 – Mar 3
TomatoesTransplant · Apr 21 – May 5
Peppers, eggplantStart indoors · Feb 3 – Feb 17
Peppers, eggplantTransplant · Apr 28 – May 12
BeansSow outdoors · Apr 21 – May 5
Sweet cornSow outdoors · Apr 21 – May 5
Cucumbers, squashSow outdoors · Apr 21 – May 5
Fall lettuce, spinachSow outdoors · Aug 29 – Sep 12
GarlicPlant cloves · Oct 10 – Nov 14
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 14) and first fall frost (Oct 24) 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 06420 came on Apr 5 — 3 days earlier than the 1991–2020 average (Apr 8).

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 Salem, CT.

Soil in Salem, CT

The soil mapped at the center of ZIP 06420 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 06420; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Salem, CT

Summer high84 °Faverage high, July
Winter low21 °Faverage low, January
Hot days14days a year at 90 °F or more
Freezing nights124nights a year at 32 °F or less
Growing degree days3,066base 50 °F — the season’s usable heat
Longest day15 h 11 mindaylight on June 21
Shortest day9 h 10 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation52.2 inper year, rain and melted snow
Snowfall28 inper year; 30 days with snow on the ground

Average high and low, by month

10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 38 °F, low 21 °F 38°21° JanFebruary: average high 41 °F, low 23 °F 41°23° FebMarch: average high 48 °F, low 29 °F 48°29° MarApril: average high 59 °F, low 39 °F 59°39° AprMay: average high 70 °F, low 49 °F 70°49° MayJune: average high 78 °F, low 59 °F 78°59° JunJuly: average high 84 °F, low 65 °F 84°65° JulAugust: average high 83 °F, low 63 °F 83°63° AugSeptember: average high 76 °F, low 55 °F 76°55° SepOctober: average high 64 °F, low 44 °F 64°44° OctNovember: average high 53 °F, low 34 °F 53°34° NovDecember: average high 43 °F, low 27 °F 43°27° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″6″January: 3.89 in precipitation, 9 in snowfall 3.9❄9 JanFebruary: 3.75 in precipitation, 7.1 in snowfall 3.8❄7 FebMarch: 5.09 in precipitation, 5 in snowfall 5.1❄5 MarApril: 4.71 in precipitation, 0.8 in snowfall 4.7❄1 AprMay: 3.64 in precipitation 3.6 MayJune: 4.27 in precipitation 4.3 JunJuly: 3.63 in precipitation 3.6 JulAugust: 4.41 in precipitation 4.4 AugSeptember: 4.79 in precipitation 4.8 SepOctober: 4.86 in precipitation 4.9 OctNovember: 4.17 in precipitation, 0.3 in snowfall 4.2 NovDecember: 4.97 in precipitation, 5.6 in snowfall 5.0❄6 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Norwich Public Utility Plt, CT (11 mi away); precipitation: Norwich Public Utility Plt, CT (11 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.

063706b
Oakdale, CT · 4 mi
063346b
Bozrah, CT · 6 mi
064156b
Colchester, CT · 6 mi
063366b
Gilman, CT · 7 mi
063826b
Uncasville, CT · 7 mi
064236b
East Haddam, CT · 7 mi
063337a
East Lyme, CT · 7 mi
063896b
Yantic, CT · 9 mi

Connecticut planting zones →

Questions about 06420

What planting zone is ZIP code 06420?

ZIP code 06420 (Salem, 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 Salem, CT?

The median last spring frost (32 °F) near 06420 is April 14; after April 30 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Norwich Public Utility Plt station.

When is the first frost in Salem, CT?

The median first fall frost near 06420 is October 24, giving a median frost-free growing season of 192 days.

When should I plant tomatoes in 06420?

Start tomato seeds indoors around Feb 17 – Mar 3 and set transplants outside around Apr 21 – May 5, one to three weeks after the median last frost.

How much rain and snow does 06420 get?

About 52.2 inches of precipitation a year and 28 inches of snowfall (NOAA 1991–2020 normals, Norwich Public Utility Plt station).

How hot do summers get in Salem, CT?

The average high peaks at 84 °F in July, with about 14 days a year at 90 °F or more.

What kind of soil does 06420 have?

The USDA soil survey maps Woodbridge at the center of ZIP 06420: moderately decomposed plant material, moderately well drained.

Did spring come early in Salem, CT in 2026?

Spring leaf-out near 06420 came on Apr 5 in 2026, 3 days earlier than the 1991–2020 average (Apr 8), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Salem, CT?

Long-day onions: the longest day near 06420 is 15 h 11 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 06420 change?

Yes. The 2012 USDA map put 06420 in zone 6a; the 2023 map puts it in zone 6b. The newer map uses 1991–2020 data and more weather stations.