Rocky Hill, New Jersey, sits in USDA hardiness zone 7a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
These conditions suit cabbage, hazelnut, california poppy, and collard greens — a starting list any specific site will trim or extend with its own soil, sun, and drainage.
Even in Rocky Hill, 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 Rocky Hill 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 Rocky Hill — soil, climate, flood, and parcel records. How we handle your address.
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Rocky Hill — the short answer
Rocky Hill, New Jersey: USDA zone 7a, about 216 days between hard freezes, across 390 acres of town.
- USDA zone
- 7a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 2
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Nov 4
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~216
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 390 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 Rocky Hill's average, not your lot's — a low corner or a tree line moves it. Against Rocky Hill's 216-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Rocky Hill
Each reading below is measured for Rocky Hill itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredRocky Hill runs about 216 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
MeasuredRocky Hill 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 Rocky Hill is in
Rocky Hill sits in the Northern Piedmont — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Rocky Hill's own centroid rather than borrowed from Somerset County.
What Grows in Rocky Hill
Every plant below cleared Rocky Hill's own zone 7a and its 216-day season. Each card opens that plant's New Jersey profile. How we score.
Is it too late to plant in Rocky Hill?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Mar 5; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 2 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 4 — 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 Rocky Hill
Spotted lanternfly documented 4 miles from Rocky Hill, first recorded 2019. What to watch for.
What's on the federal record near Rocky Hill
Closest first, within ~10 miles of Rocky Hill. Listing isn't leaking, and distance isn't exposure.
- PRINCETON GAMMA TECH INCUnderground Storage Tanks · 200 ft
- ENACHIP INCBrownfields · 200 ft
- ENACHIP, INCBrownfields · 300 ft
- CHURCH & DWIGHT CO INC - ROCKY HILLBrownfields · 350 ft
- G & W RFID LLCBrownfields · 550 ft
- 350006-- PW 2Nitrate · 2400 ft
- ROCKY HILL MUNICIPAL WELLSuperfund · 2400 ft
- TEXACO SERVICE STATION #100148Underground Storage Tanks · 0.6 mi
- STAR TEXACO INC NJ 0014Underground Storage Tanks · 0.6 mi
- MONTGOMERY KNOLLS BOOSTER STATIONUnderground Storage Tanks · 0.6 mi
- GOODYEAR TIRE CENTER 5252Underground Storage Tanks · 0.6 mi
- PRINCETON AUVW LLCUnderground Storage Tanks · 0.6 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Rocky Hill'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 Rocky Hill.
Sources Checked
within ~10 miles of Rocky Hill
Severity Distribution
within ~10 miles of Rocky Hill
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Rocky Hill, Superfund runs higher than the national average — 37 sites within ~10 miles of Rocky Hill. That's not a problem with your land — it's information about it.
Superfund: Superfund sites represent the most severe contamination in the federal system.
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Check your specific parcel in Rocky Hill
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 Rocky Hill average
Your land is one point inside Rocky Hill
Everything above resolves to Rocky Hill as a whole — one PHZM band and one 28°F frost record, read across 390 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 Rocky Hill Average
Rocky Hill Average
- ●USDA Zones 7a, averaged across Rocky Hill
- ●One soil character for all of Rocky Hill
- ●Frost dates read at Rocky Hill's scale: Apr 2 to Nov 4
YOUR Parcel
- ✓Your exact zone, not Rocky Hill's 7a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Rocky Hill
Pull a site-specific report for your exact address in Rocky Hill, New Jersey — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Rocky Hill averages can't show:
We read public map data around Rocky Hill — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Rocky Hill average
How we know this about Rocky Hill
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 Rocky Hill’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 Rocky Hill
When does frost risk typically end in Rocky Hill?
The last hard freeze (28°F) in Rocky Hill typically lands around Apr 2, 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 23.
When is the first frost in Rocky Hill?
The first hard freeze (28°F) in Rocky Hill typically arrives around Nov 4, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 21, so the watching starts about Oct 5 — about 216 days after the spring freeze cleared.
How long is the growing season in Rocky Hill?
Measured between 28°F hard freezes, Rocky Hill sees about 216 frost-free days — roughly Apr 2 through Nov 4, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 23 to Oct 21, about 181 days.
Is the soil safe to grow vegetables in Rocky Hill?
The federal record around Rocky Hill runs heavier than most — 1,601 documented sites, mostly Underground Storage Tanks entries (690), the nearest Underground Storage Tanks record under a tenth of a mile 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 Rocky Hill?
From about Oct 5 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 4 (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 4. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Rocky Hill's scale — its 7a band and its 216-day season. Your yard writes its own version of Rocky Hill'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 Rocky Hill’s own scale
7 of the readings below were taken at Rocky Hill's own scale — its own ~216-day season between 28°F freezes, the 390 acres it covers and 1,601 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Rocky Hill's own USDA hardiness band, zones 7aUSDA PHZM 2023
- Rocky Hill's own 28°F hard-freeze dates, about Apr 2 and Nov 4 and the ~216-day span between themNOAA 1991–2020 Climate Normals
- 1,601 documented contamination sites on the federal record near Rocky Hill, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Rocky Hill's boundary and the 390 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7a and a ~216-day seasonGrowable Ground crop-matching engine
- The ecoregion at Rocky Hill's own centroid, the Northern PiedmontUS EPA Level III Ecoregions
- A documented spotted-lanternfly record within reach of Rocky Hilllydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- Soil character — no town-scale survey exists, so Rocky Hill's 390 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 Rocky Hill's 390 acreswhy one lot differs from the next →
- Which side of Rocky Hill you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 390 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 Rocky Hill-wide figureread your own land →
More in New Jersey
Wider growing context
What grows across New JerseyRocky Hill sits outside our named growing regions, so New Jersey as a whole is its closest context here.
Nearby growing guides