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

Planting zone for New Haven, CT

New Haven, CT is in USDA zones 6b to 7a across its 28 ZIP codes. The median last spring frost is April 17 and the first fall frost October 27.

New Haven on the zone map

Outlined: its 7 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.

Zones6b–7a−5 to 5 °F
ZIP codes28
Last frostApr 17
First frostOct 27
Growing season193 days

6b 1 ZIP   7a 27 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

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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 New Haven, CT

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 17median — 50% chance of a later frost
Safe for tender plantsMay 1only 10% chance of frost after
First fall frostOctober 27median — 10% chance by Oct 11
Growing season193 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 4 and returns around November 6.

From the NOAA station New Haven Tweed Airport, CT, elevation 3 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 New Haven

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 6 – Mar 20
SpinachSow outdoors · Mar 6 – Mar 27
Broccoli, cabbageStart indoors · Feb 6 – Feb 20
Broccoli, cabbageTransplant · Mar 27 – Apr 10
Onion setsPlant outdoors · Mar 20 – Apr 3
PotatoesPlant outdoors · Mar 27 – Apr 10
LettuceSow outdoors · Mar 20 – Apr 3
Carrots, beetsSow outdoors · Mar 27 – Apr 10
TomatoesStart indoors · Feb 20 – Mar 6
TomatoesTransplant · Apr 24 – May 8
Peppers, eggplantStart indoors · Feb 6 – Feb 20
Peppers, eggplantTransplant · May 1 – May 15
BeansSow outdoors · Apr 24 – May 8
Sweet cornSow outdoors · Apr 24 – May 8
Cucumbers, squashSow outdoors · Apr 24 – May 8
Fall lettuce, spinachSow outdoors · Sep 1 – Sep 15
GarlicPlant cloves · Oct 13 – Nov 17
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 17) and first fall frost (Oct 27) 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 06511 came on Apr 2 — about the same time as the 1991–2020 average (Apr 1).

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 New Haven, CT.

Soil in New Haven, CT

The soil mapped at the center of ZIP 06511 is Udorthents — loam, poorly drained. Much of the area is built over (urban land); this is the natural soil underneath.

TextureLoama good balance for most vegetables
pH5.6moderately acidic; most vegetables like 6.0–7.0
DrainagePoorly drainedconsider raised beds
Organic matter4%moderate
Hydrologic groupBwater soaks in moderately
Farmland classNot prime farmlandUSDA classification

Map unit: Urban land.

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 06511; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in New Haven, CT

Summer high82 °Faverage high, July
Winter low23 °Faverage low, January
Hot days6days a year at 90 °F or more
Freezing nights102nights a year at 32 °F or less
Growing degree days3,028base 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)
Precipitation41.8 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 38 °F, low 23 °F 38°23° JanFebruary: average high 40 °F, low 24 °F 40°24° FebMarch: average high 47 °F, low 30 °F 47°30° MarApril: average high 58 °F, low 39 °F 58°39° AprMay: average high 68 °F, low 49 °F 68°49° MayJune: average high 76 °F, low 59 °F 76°59° JunJuly: average high 82 °F, low 66 °F 82°66° JulAugust: average high 81 °F, low 65 °F 81°65° AugSeptember: average high 75 °F, low 57 °F 75°57° SepOctober: average high 64 °F, low 46 °F 64°46° OctNovember: average high 53 °F, low 36 °F 53°36° NovDecember: average high 44 °F, low 29 °F 44°29° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 2.72 in precipitation 2.7 JanFebruary: 2.84 in precipitation 2.8 FebMarch: 3.66 in precipitation 3.7 MarApril: 4.19 in precipitation 4.2 AprMay: 3.54 in precipitation 3.5 MayJune: 3.47 in precipitation 3.5 JunJuly: 3.36 in precipitation 3.4 JulAugust: 3.55 in precipitation 3.5 AugSeptember: 4.03 in precipitation 4.0 SepOctober: 3.78 in precipitation 3.8 OctNovember: 3.12 in precipitation 3.1 NovDecember: 3.53 in precipitation 3.5 Dec

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

ZIP codes in New Haven

065017a
0 to 5 °F
065027a
0 to 5 °F
065037a
0 to 5 °F
065047a
0 to 5 °F
065057a
0 to 5 °F
065067a
0 to 5 °F
065077a
0 to 5 °F
065087a
0 to 5 °F
065097a
0 to 5 °F
065107a
0 to 5 °F
065117a
0 to 5 °F
065127a
0 to 5 °F
065137a
0 to 5 °F
065157a
0 to 5 °F
065197a
0 to 5 °F
065207a
0 to 5 °F
065217a
0 to 5 °F
065256b
−5 to 0 °F
065307a
0 to 5 °F
065317a
0 to 5 °F
065327a
0 to 5 °F
065337a
0 to 5 °F
065347a
0 to 5 °F
065357a
0 to 5 °F
065367a
0 to 5 °F
065377a
0 to 5 °F
065387a
0 to 5 °F
065407a
0 to 5 °F

Connecticut planting zones →

Questions about New Haven

What planting zone is New Haven, CT?

New Haven, CT is in USDA hardiness zones 6b to 7a on the 2023 map (6b: −5 to 0 °F; 7a: 0 to 5 °F).

When is the last frost in New Haven, CT?

The median last spring frost is April 17 and the median first fall frost is October 27 (NOAA 1991–2020 normals, New Haven Tweed Airport station).

When can I plant a garden in New Haven, CT?

Cool-season crops like peas and spinach go in around Mar 6 – Mar 27; tomatoes, peppers, beans and squash after about Apr 24, once frost risk has passed.

What kind of onions grow in New Haven, CT?

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

How much rain and snow does New Haven, CT get?

About 41.8 inches of precipitation a year (NOAA 1991–2020 normals).