New Haven, Connecticut, sits in USDA hardiness zone 7a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
Expect cabbage, hazelnut, california poppy, and collard greens to be strong candidates here; the deciding factors on any one parcel stay local — soil, sun, and drainage.
Even in New Haven, no two yards are alike.
A low spot, a south-facing slope, or a stand of trees moves the frost date and sun across a single New Haven lot. Enter your address and we'll score 1,086 plants against your land's actual soil, sun, and frost.
We read public map data around New Haven — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
New Haven — the short answer
New Haven, Connecticut: USDA zone 7a, about 233 days between hard freezes, across 12K acres of city.
- USDA zone
- 7a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 27
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Nov 15
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~233
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 12K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are this town’s own 28°F normals: light frosts run a few weeks past them, and tender transplants usually wait 2–3 weeks after the last hard freeze.
Hardiness Zone Range
Zone 7a is New Haven's average, not your lot's — a low corner or a tree line moves it. Against New Haven's 233-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in New Haven
Each reading below is measured for New Haven itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredNew Haven runs about 233 days between hard freezes — a long growing season.
There is slack for succession plantings and slow-finishing crops: many vegetables can be sown twice, and the heat-lovers have time to ripen fully.
Plan a second sowing of quick crops after the first comes out, and use the fall window most gardeners let sit idle.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredNew Haven sits in USDA hardiness zone 7a.
The zone sets which perennials, shrubs, and fruit trees live through an average winter here — a plant rated for a colder zone is a safe bet, one rated warmer needs winter protection or gets treated as an annual.
Match perennials and fruit to the zone before you buy, so nothing you plant is a gamble against the cold.
USDA PHZM 2023
The kind of country New Haven is in
New Haven sits in the Northeastern Coastal Zone — EPA Level III, inside the wider Eastern Temperate Forests. That is read at New Haven's own centroid rather than borrowed from South Central Connecticut Planning Region.
What Grows in New Haven
Every plant below cleared New Haven's own zone 7a and its 233-day season. Each card opens that plant's Connecticut profile. How we score.
Is it too late to plant in New Haven?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Feb 27; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 27 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 15 — long-season crops need about 90 days of runway, quick greens only 30. With a season this long, “too late” mostly means “switch crops” — second sowings and a full fall garden are the norm, with garlic closing the year.
Documented around New Haven
Spotted lanternfly documented 3 miles from New Haven, first recorded 2022. What to watch for.
What's on the federal record near New Haven
Closest first, within ~10 miles of New Haven. Listing isn't leaking, and distance isn't exposure.
- 1 HILLHOUSE AVENUEUnderground Storage Tanks · 300 ft
- FOUNDRY BUILDINGBrownfields · 800 ft
- YALE HEALTH CENTERUnderground Storage Tanks · 850 ft
- NEW HAVEN CO #2 (1111)Underground Storage Tanks · 1000 ft
- FASMART#1318Underground Storage Tanks · 1000 ft
- FORMER GEOMETRIC TOOL COMPANYUnderground Storage Tanks · 1000 ft
- NEW HAVEN NEW ENGLAND PETROLEUMUnderground Storage Tanks · 1000 ft
- FIRE STATIONUnderground Storage Tanks · 1000 ft
- STATE / WALL STREET GARAGE #1107Underground Storage Tanks · 1000 ft
- CROISSANT BAKERY, INC.Underground Storage Tanks · 1000 ft
- BOWEN FIELDUnderground Storage Tanks · 1000 ft
- HOWE STREET RESIDENCEUnderground Storage Tanks · 1000 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from New Haven's center, not your beds. Run your own address for what's upwind of you specifically.
Environmental Intelligence
The counts behind that headline — every source type on the record near New Haven.
Total Sites
2,335
within ~10 miles of New Haven
Risk Level
Elevated
Highest-severity
27 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of New Haven
Severity Distribution
within ~10 miles of New Haven
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around New Haven, Toxics Release Inventory runs higher than the national average — 159 sites within ~10 miles of New Haven. It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Check your specific parcel in New Haven
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,086 plant recommendations.
25+ data sources read at your address, not the New Haven average
Your land is one point inside New Haven
Everything above resolves to New Haven as a whole — one PHZM band and one 28°F frost record, read across 12K acres. Your parcel is one point inside that footprint. Slope, tree cover, a low spot that pools cold air, and what is in the soil are all resolved at the address, and none of them are visible at city scale. That is the honest boundary of this page, and the reason the next step is a reading of your own ground rather than a better local average.
Your Lot vs the New Haven Average
New Haven Average
- ●USDA Zones 7a, averaged across New Haven
- ●One soil character for all of New Haven
- ●Frost dates read at New Haven's scale: Mar 27 to Nov 15
YOUR Parcel
- ✓Your exact zone, not New Haven's 7a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in New Haven
Pull a site-specific report for your exact address in New Haven, Connecticut — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that New Haven averages can't show:
We read public map data around New Haven — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the New Haven average
How we know this about New Haven
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this city’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at New Haven’s own record; boundaries and acreage from US Census TIGER/Line 2025; the contamination records from the federal sources named in their beats above. Soil is not read at city grain anywhere on this page — there is no city-resolution survey in our data, which is why you will find no soil grid here rather than a statewide one wearing a local label. The resolution ledger below names every figure this page inherited.
Common questions about New Haven
When does frost risk typically end in New Haven?
The last hard freeze (28°F) in New Haven typically lands around Mar 27, per NOAA 1991–2020 climate normals — earlier than the light-frost dates most charts quote. That marks the hard freeze, not the last light frost — lighter frosts keep biting past it, which is why tender transplants here wait until about Apr 17.
When is the first frost in New Haven?
The first hard freeze (28°F) in New Haven typically arrives around Nov 15, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 1, so the watching starts about Oct 16 — about 233 days after the spring freeze cleared.
How long is the growing season in New Haven?
Measured between 28°F hard freezes, New Haven sees about 233 frost-free days — roughly Mar 27 through Nov 15, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 17 to Nov 1, about 198 days.
Is the soil safe to grow vegetables in New Haven?
The federal record around New Haven is a meaningful one — 2,335 documented sites, mostly Underground Storage Tanks entries (1,209), the nearest Underground Storage Tanks record under a tenth of a mile out — so a soil test before new food beds is a sensible precaution here, not a reason to hold back from growing. Remember that proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what sits where.
How do I protect my plants from frost in New Haven?
From about Oct 16 the job here turns from planting to protecting — the last start even a 30-day crop can finish. As the season closes around the first 28°F hard freeze near Nov 15 (NOAA 1991–2020 climate normals), three moves buy time: row cover or an old sheet over tender plants on still, clear nights; water the soil the afternoon before a freeze, so it holds warmth overnight; and harvest tomatoes, peppers and basil before Nov 15. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at New Haven's scale — its 7a band and its 233-day season. Your yard writes its own version of New Haven's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
What this page reads at New Haven’s own scale
7 of the readings below were taken at New Haven's own scale — its own ~233-day season between 28°F freezes, the 11,962 acres it covers and 2,335 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- New Haven's own USDA hardiness band, zones 7aUSDA PHZM 2023
- New Haven's own 28°F hard-freeze dates, about Mar 27 and Nov 15 and the ~233-day span between themNOAA 1991–2020 Climate Normals
- 2,335 documented contamination sites on the federal record near New Haven, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- New Haven's boundary and the 11,962 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7a and a ~233-day seasonGrowable Ground crop-matching engine
- The ecoregion at New Haven's own centroid, the Northeastern Coastal ZoneUS EPA Level III Ecoregions
- A documented spotted-lanternfly record within reach of New Havenlydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- Soil character — no town-scale survey exists, so New Haven's 11,962 acres read through its county's SSURGO summaryfrom South Central Connecticut County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom South Central Connecticut County
- The growing challenges every Connecticut grower plans around — written at state scale, so they stay on the state guidefrom Connecticut
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom South Central Connecticut County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among New Haven's 11,962 acreswhy one lot differs from the next →
- Which side of New Haven you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 11,962 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record under a tenth of a mile out, measured from the town centrehow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — measured at your address, and averaged away by any New Haven-wide figureread your own land →
More in Connecticut
Wider growing context
What grows across ConnecticutNew Haven sits outside our named growing regions, so Connecticut as a whole is its closest context here.
Nearby growing guides