Twin Rocks, Pennsylvania, sits in USDA hardiness zone 6a — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
Crops well matched to these conditions include cabbage, hazelnut, lavender, and collard greens — though what thrives on any one site still turns on its specific soil, sun, and drainage.
Even in Twin Rocks, 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 Twin Rocks 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 Twin Rocks — soil, climate, flood, and parcel records. How we handle your address.
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Twin Rocks — the short answer
Twin Rocks, Pennsylvania: USDA zone 6a, about 185 days between hard freezes, across 383 acres of town.
- USDA zone
- 6a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 23
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 25
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~185
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 383 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 6a is Twin Rocks's average, not your lot's — a low corner or a tree line moves it. Against Twin Rocks's 185-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Twin Rocks
Each reading below is measured for Twin Rocks itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredTwin Rocks runs about 185 days between hard freezes — a moderate growing season.
There is room for the full run of cool-season crops plus a warm-season main crop, but the calendar is tight enough that a late spring or early fall frost still decides how much finishes.
Time warm-season transplants to your last hard freeze, and a few weeks of season extension turns a near-miss harvest into a sure one.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredTwin Rocks sits in USDA hardiness zone 6a.
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 Twin Rocks is in
Twin Rocks sits in the Central Appalachians — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Twin Rocks's own centroid rather than borrowed from Cambria County.
What Grows in Twin Rocks
Every plant below cleared Twin Rocks's own zone 6a and its 185-day season. Each card opens that plant's Pennsylvania profile. How we score.
Is it too late to plant in Twin Rocks?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Mar 26; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 23 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 25 — long-season crops need about 90 days of runway, quick greens only 30. As the window narrows, the plantings just get faster — fall brassicas, then greens, then garlic to finish.
Documented around Twin Rocks
Spotted lanternfly documented 3 miles from Twin Rocks, first recorded 2022. What to watch for.
What's on the federal record near Twin Rocks
Closest first, within ~10 miles of Twin Rocks. Listing isn't leaking, and distance isn't exposure.
- LANZENDORFER TRUCKINGUnderground Storage Tanks · 1100 ft
- CA 103Nitrate · 2100 ft
- RUMMEL BROTHERS LUMBER COBrownfields · 0.7 mi
- JOHN & MARY BORTNYIK MOBILUnderground Storage Tanks · 1.1 mi
- BLACKLICK TWP SPVRUnderground Storage Tanks · 1.7 mi
- NANTY GLO SEW PLTUnderground Storage Tanks · 2.2 mi
- EBENSBURG BORO MUNI AUTHPFAS · 2.2 mi
- JACKSONUnderground Storage Tanks · 2.2 mi
- EBENSBURGUnderground Storage Tanks · 2.4 mi
- STEVES EXXONUnderground Storage Tanks · 2.4 mi
- OLD SHEETZ 48Underground Storage Tanks · 2.5 mi
- GEORGES AUTOBrownfields · 2.5 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Twin Rocks'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 Twin Rocks.
Total Sites
346
within ~10 miles of Twin Rocks
Risk Level
Elevated
Highest-severity
12 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Twin Rocks
Severity Distribution
within ~10 miles of Twin Rocks
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Twin Rocks, two things run higher than the national average within ~10 miles of Twin Rocks — PFAS (5 sites) and Nitrate (140 sites). That's not a problem with your land — it's information about it.
PFAS: PFAS (per- and polyfluoroalkyl substances) are called "forever chemicals" because they do not biodegrade.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Test irrigation water source — this is the primary pathway for PFAS to reach garden crops.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in Twin Rocks
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 Twin Rocks average
Your land is one point inside Twin Rocks
Everything above resolves to Twin Rocks as a whole — one PHZM band and one 28°F frost record, read across 383 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 Twin Rocks Average
Twin Rocks Average
- ●USDA Zones 6a, averaged across Twin Rocks
- ●One soil character for all of Twin Rocks
- ●Frost dates read at Twin Rocks's scale: Apr 23 to Oct 25
YOUR Parcel
- ✓Your exact zone, not Twin Rocks's 6a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Twin Rocks
Pull a site-specific report for your exact address in Twin Rocks, Pennsylvania — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Twin Rocks averages can't show:
We read public map data around Twin Rocks — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Twin Rocks average
How we know this about Twin Rocks
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 Twin Rocks’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 Twin Rocks
When does frost risk typically end in Twin Rocks?
The last hard freeze (28°F) in Twin Rocks typically lands around Apr 23, 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 14.
When is the first frost in Twin Rocks?
The first hard freeze (28°F) in Twin Rocks typically arrives around Oct 25, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 11, so the watching starts about Sep 25 — about 185 days after the spring freeze cleared.
How long is the growing season in Twin Rocks?
Measured between 28°F hard freezes, Twin Rocks sees about 185 frost-free days — roughly Apr 23 through Oct 25, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 14 to Oct 11, about 150 days.
Is the soil safe to grow vegetables in Twin Rocks?
The federal record around Twin Rocks is a meaningful one — 346 documented sites, mostly Nitrate entries (140), the nearest Underground Storage Tanks record about 0.2 miles 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 Twin Rocks?
From about Sep 25 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 25 (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 25. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Twin Rocks's scale — its 6a band and its 185-day season. Your yard writes its own version of Twin Rocks'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 Twin Rocks’s own scale
7 of the readings below were taken at Twin Rocks's own scale — its own ~185-day season between 28°F freezes, the 383 acres it covers and 346 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Twin Rocks's own USDA hardiness band, zones 6aUSDA PHZM 2023
- Twin Rocks's own 28°F hard-freeze dates, about Apr 23 and Oct 25 and the ~185-day span between themNOAA 1991–2020 Climate Normals
- 346 documented contamination sites on the federal record near Twin Rocks, the closest Underground Storage Tanks record about 0.2 miles out from the town centreFederal environmental registers
- Twin Rocks's boundary and the 383 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6a and a ~185-day seasonGrowable Ground crop-matching engine
- The ecoregion at Twin Rocks's own centroid, the Central AppalachiansUS EPA Level III Ecoregions
- A documented spotted-lanternfly record within reach of Twin Rockslydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- Soil character — no town-scale survey exists, so Twin Rocks's 383 acres read through its county's SSURGO summaryfrom Cambria County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Cambria County
- The growing challenges every Pennsylvania grower plans around — written at state scale, so they stay on the state guidefrom Pennsylvania
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Cambria County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Twin Rocks's 383 acreswhy one lot differs from the next →
- Which side of Twin Rocks you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 383 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks 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 Twin Rocks-wide figureread your own land →