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

Planting zone for 06371 — Old Lyme, CT

ZIP code 06371 (Old Lyme, Lower Connecticut River Valley County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is April 16 and the first fall frost October 28.

Where ZIP 06371 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.

Zone7a0 to 5 °F

Coldest night−17.8 to −15 °C

Last frostApr 16

First frostOct 28

2012 zone6b

Was 6b 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 7a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Old Lyme, 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 Old Lyme, CT

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostApril 16median — 50% chance of a later frost

Safe for tender plantsApril 30only 10% chance of frost after

First fall frostOctober 28median — 10% chance by Oct 13

Growing season194 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 3 and returns around November 9.

From the NOAA station Groton New London Airport, CT — 14 miles away, elevation 10 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 06371

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 5 – Mar 19

SpinachSow outdoors · Mar 5 – Mar 26

Broccoli, cabbageStart indoors · Feb 5 – Feb 19

Broccoli, cabbageTransplant · Mar 26 – Apr 9

Onion setsPlant outdoors · Mar 19 – Apr 2

PotatoesPlant outdoors · Mar 26 – Apr 9

LettuceSow outdoors · Mar 19 – Apr 2

Carrots, beetsSow outdoors · Mar 26 – Apr 9

TomatoesStart indoors · Feb 19 – Mar 5

TomatoesTransplant · Apr 23 – May 7

Peppers, eggplantStart indoors · Feb 5 – Feb 19

Peppers, eggplantTransplant · Apr 30 – May 14

BeansSow outdoors · Apr 23 – May 7

Sweet cornSow outdoors · Apr 23 – May 7

Cucumbers, squashSow outdoors · Apr 23 – May 7

Fall lettuce, spinachSow outdoors · Sep 2 – Sep 16

GarlicPlant cloves · Oct 14 – Nov 18

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 16) and first fall frost (Oct 28) 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 06371 came on Apr 3 — about the same time as the 1991–2020 average (Apr 4).

average
Apr 42026
Apr 3

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 7a in Connecticut

546 plants native to the lower 48 states, recorded in Connecticut, and rated by the USDA to survive 0 °F or colder — the bottom of zone 7a. 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 Old Lyme, CT.

Soil in Old Lyme, CT

The soil mapped at the center of ZIP 06371 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 06371; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Old Lyme, CT

Summer high80 °Faverage high, July

Winter low23 °Faverage low, January

Hot days2days a year at 90 °F or more

Freezing nights107nights a year at 32 °F or less

Growing degree days2,786base 50 °F — the season’s usable heat

Longest day15 h 10 mindaylight on June 21

Shortest day9 h 11 mindaylight on December 21

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

Precipitation47.8 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Groton New London Airport, CT (14 mi away); precipitation: Old Lyme 3.4 Ese, CT (5 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.

Old Saybrook, CT · 5 mi

064396b

Hadlyme, CT · 5 mi

064097a

Centerbrook, CT · 6 mi

064427a

Ivoryton, CT · 6 mi

063767a

South Lyme, CT · 6 mi

063577a

Niantic, CT · 6 mi

Connecticut planting zones →

Questions about 06371

What planting zone is ZIP code 06371?

ZIP code 06371 (Old Lyme, CT) is in USDA hardiness zone 7a on the 2023 map: the coldest night of an average winter reaches 0 to 5 °F (−17.8 to −15 °C).

When is the last frost in Old Lyme, CT?

The median last spring frost (32 °F) near 06371 is April 16; after April 30 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Groton New London Airport station.

When is the first frost in Old Lyme, CT?

The median first fall frost near 06371 is October 28, giving a median frost-free growing season of 194 days.

When should I plant tomatoes in 06371?

Start tomato seeds indoors around Feb 19 – Mar 5 and set transplants outside around Apr 23 – May 7, one to three weeks after the median last frost.

How much rain and snow does 06371 get?

About 47.8 inches of precipitation a year (NOAA 1991–2020 normals, Old Lyme 3.4 Ese station).

How hot do summers get in Old Lyme, CT?

The average high peaks at 80 °F in July, with about 2 days a year at 90 °F or more.

What kind of soil does 06371 have?

The USDA soil survey maps Woodbridge at the center of ZIP 06371: moderately decomposed plant material, moderately well drained.

Did spring come early in Old Lyme, CT in 2026?

Spring leaf-out near 06371 came on Apr 3 in 2026, about the same as the 1991–2020 average (Apr 4), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Old Lyme, CT?

Long-day onions: the longest day near 06371 is 15 h 10 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 06371 change?

Yes. The 2012 USDA map put 06371 in zone 6b; the 2023 map puts it in zone 7a. The newer map uses 1991–2020 data and more weather stations.