Green Knoll, New Jersey, sits in USDA hardiness zone 7a — a zone band wide enough that plant choice, not possibility, is the interesting question.
Among the crops suited to this profile: cabbage, pawpaw, california poppy, and collard greens. The site-level story — soil, sun, drainage — decides the rest.
Even in Green Knoll, 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 Green Knoll 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 Green Knoll — soil, climate, flood, and parcel records. How we handle your address.
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Green Knoll — the short answer
Green Knoll, New Jersey: USDA zone 7a, about 200 days between hard freezes, across 3K acres of town.
- USDA zone
- 7a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 10
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 27
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~200
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 3K 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 Green Knoll's average, not your lot's — a low corner or a tree line moves it. Against Green Knoll's 200-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Green Knoll
Each reading below is measured for Green Knoll itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredGreen Knoll runs about 200 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
MeasuredGreen Knoll 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 Green Knoll is in
Green Knoll sits in the Northern Piedmont — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Green Knoll's own centroid rather than borrowed from Somerset County.
What Grows in Green Knoll
Every plant below cleared Green Knoll's own zone 7a and its 200-day season. Each card opens that plant's New Jersey profile. How we score.
Is it too late to plant in Green Knoll?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Mar 13; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 10 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 27 — long-season crops need about 90 days of runway, quick greens only 30. A long window like this one runs successions deep into fall — and even its last weeks take quick greens and garlic.
Documented around Green Knoll
Spotted lanternfly documented 2 miles from Green Knoll, first recorded 2019. What to watch for.
What's on the federal record near Green Knoll
Closest first, within ~10 miles of Green Knoll. Listing isn't leaking, and distance isn't exposure.
- Somerville Copper MineMining · 850 ft
- REPLIGEN CORP. - PROCESS ANALYTICSBrownfields · 0.5 mi
- FENNESSEY BUICK INCUnderground Storage Tanks · 0.6 mi
- HOME DEPOT STORE #962Brownfields · 0.7 mi
- American MineMining · 0.7 mi
- 350036-- 1-1961Nitrate · 0.8 mi
- SOLARIS PHARMA CORPBrownfields · 0.8 mi
- American Bridgewater Mine/Hoffman MineMining · 0.8 mi
- SOMERSET COUNTY SHOPPING CTRBrownfields · 0.8 mi
- BRIDGEWATER TWPUnderground Storage Tanks · 1.0 mi
- AMERICAN CYANAMID COUnderground Storage Tanks · 1.0 mi
- BLOOMINGDALES - BRIDGEWATER COMMONSBrownfields · 1.1 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Green Knoll'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 Green Knoll.
Sources Checked
within ~10 miles of Green Knoll
Severity Distribution
within ~10 miles of Green Knoll
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Green Knoll, two things run higher than the national average within ~10 miles of Green Knoll — Superfund (56 sites) and Toxics Release Inventory (124 sites). Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
Superfund: Superfund sites represent the most severe contamination in the federal system.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Check your specific parcel in Green Knoll
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 Green Knoll average
Your land is one point inside Green Knoll
Everything above resolves to Green Knoll as a whole — one PHZM band and one 28°F frost record, read across 3K 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 town 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 Green Knoll Average
Green Knoll Average
- ●USDA Zones 7a, averaged across Green Knoll
- ●One soil character for all of Green Knoll
- ●Frost dates read at Green Knoll's scale: Apr 10 to Oct 27
YOUR Parcel
- ✓Your exact zone, not Green Knoll's 7a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Green Knoll
Pull a site-specific report for your exact address in Green Knoll, New Jersey — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Green Knoll averages can't show:
We read public map data around Green Knoll — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Green Knoll average
How we know this about Green Knoll
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this town’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Green Knoll’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 town grain anywhere on this page — there is no town-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 Green Knoll
When does frost risk typically end in Green Knoll?
The last hard freeze (28°F) in Green Knoll typically lands around Apr 10, 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 May 1.
When is the first frost in Green Knoll?
The first hard freeze (28°F) in Green Knoll typically arrives around Oct 27, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 13, so the watching starts about Sep 27 — about 200 days after the spring freeze cleared.
How long is the growing season in Green Knoll?
Measured between 28°F hard freezes, Green Knoll sees about 200 frost-free days — roughly Apr 10 through Oct 27, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 1 to Oct 13, about 165 days.
Is the soil safe to grow vegetables in Green Knoll?
The federal record around Green Knoll runs heavier than most — 1,731 documented sites, mostly Underground Storage Tanks entries (969), the nearest Mining record about 0.2 miles out — so test the soil before planting food in the ground, and raised beds with clean imported soil grow well in the meantime. Even here, proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what's recorded and where.
How do I protect my plants from frost in Green Knoll?
From about Sep 27 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 Oct 27 (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 Oct 27. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Green Knoll's scale — its 7a band and its 200-day season. Your yard writes its own version of Green Knoll'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 Green Knoll’s own scale
7 of the readings below were taken at Green Knoll's own scale — its own ~200-day season between 28°F freezes, the 2,966 acres it covers and 1,731 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Green Knoll's own USDA hardiness band, zones 7aUSDA PHZM 2023
- Green Knoll's own 28°F hard-freeze dates, about Apr 10 and Oct 27 and the ~200-day span between themNOAA 1991–2020 Climate Normals
- 1,731 documented contamination sites on the federal record near Green Knoll, the closest Mining record about 0.2 miles out from the town centreFederal environmental registers
- Green Knoll's boundary and the 2,966 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7a and a ~200-day seasonGrowable Ground crop-matching engine
- The ecoregion at Green Knoll's own centroid, the Northern PiedmontUS EPA Level III Ecoregions
- A documented spotted-lanternfly record within reach of Green Knolllydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- Soil character — no town-scale survey exists, so Green Knoll's 2,966 acres read through its county's SSURGO summaryfrom Somerset County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Somerset County
- The growing challenges every New Jersey grower plans around — written at state scale, so they stay on the state guidefrom New Jersey
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Somerset County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Green Knoll's 2,966 acreswhy one lot differs from the next →
- Which side of Green Knoll you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 2,966 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Mining record about 0.2 miles 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 Green Knoll-wide figureread your own land →
More in New Jersey
Wider growing context
What grows across New JerseyGreen Knoll sits outside our named growing regions, so New Jersey as a whole is its closest context here.
Nearby growing guides