Williamstown, Pennsylvania, sits in USDA hardiness zone 6b — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
Expect cabbage, hazelnut, lavender, and collard greens to be strong candidates here; the deciding factors on any one parcel stay local — soil, sun, and drainage.
Even in Williamstown, 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 Williamstown 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 Williamstown — soil, climate, flood, and parcel records. How we handle your address.
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Williamstown — the short answer
Williamstown, Pennsylvania: USDA zone 6b, about 208 days between hard freezes, across 166 acres of town.
- USDA zone
- 6b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 7
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Nov 1
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~208
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 166 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 6b is Williamstown's average, not your lot's — a low corner or a tree line moves it. Against Williamstown's 208-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Williamstown
Each reading below is measured for Williamstown itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredWilliamstown runs about 208 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
MeasuredWilliamstown sits in USDA hardiness zone 6b.
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 Williamstown is in
Williamstown sits in the Ridge and Valley — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Williamstown's own centroid rather than borrowed from Dauphin County.
What Grows in Williamstown
Every plant below cleared Williamstown's own zone 6b and its 208-day season. Each card opens that plant's Pennsylvania profile. How we score.
Is it too late to plant in Williamstown?
Too late for some crops, right on time for others — a growing season is a sequence, not a deadline. Cool-season crops can go in from around Mar 10; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 7 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 1 — long-season crops need about 90 days of runway, quick greens only 30. Here the season winds down slowly: late sowings, a real autumn harvest, and garlic in the ground before the first hard freeze.
Documented around Williamstown
Spotted lanternfly documented 3 miles from Williamstown, first recorded 2019. What to watch for.
What's on the federal record near Williamstown
Closest first, within ~10 miles of Williamstown. Listing isn't leaking, and distance isn't exposure.
- FORMER RIPPS COUNTRY DELIUnderground Storage Tanks · 1800 ft
- PA DMVA WILLIAMSTOWN READINESS CTRBrownfields · 0.6 mi
- AMPUnderground Storage Tanks · 0.7 mi
- TE CONNECTIVITY CORP WILLIAMSTOWN GWCUToxics Release Inventory · 0.7 mi
- PAARNG WILLIAMSTOWN FACUnderground Storage Tanks · 0.7 mi
- WIEST MOTEL & RESTAURANTUnderground Storage Tanks · 0.7 mi
- TOWER BULK PLTUnderground Storage Tanks · 0.7 mi
- DA 604Nitrate · 0.8 mi
- PORTER TOWER JT MUNI AUTHUnderground Storage Tanks · 1.9 mi
- SGL 264Underground Storage Tanks · 2.2 mi
- MOBILUnderground Storage Tanks · 2.4 mi
- B & M TUNNELUnderground Storage Tanks · 2.8 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Williamstown'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 Williamstown.
Total Sites
261
within ~10 miles of Williamstown
Risk Level
Elevated
Highest-severity
7 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Williamstown
Severity Distribution
within ~10 miles of Williamstown
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Williamstown, two things run higher than the national average within ~10 miles of Williamstown — CAFO (11 sites) and Nitrate (126 sites). Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
CAFO: CAFOs pose a different contamination profile than chemical sources.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in Williamstown
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 Williamstown average
Your land is one point inside Williamstown
Everything above resolves to Williamstown as a whole — one PHZM band and one 28°F frost record, read across 166 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 Williamstown Average
Williamstown Average
- ●USDA Zones 6b, averaged across Williamstown
- ●One soil character for all of Williamstown
- ●Frost dates read at Williamstown's scale: Apr 7 to Nov 1
YOUR Parcel
- ✓Your exact zone, not Williamstown's 6b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Williamstown
Pull a site-specific report for your exact address in Williamstown, Pennsylvania — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Williamstown averages can't show:
We read public map data around Williamstown — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Williamstown average
How we know this about Williamstown
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 Williamstown’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 Williamstown
When does frost risk typically end in Williamstown?
The last hard freeze (28°F) in Williamstown typically lands around Apr 7, 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 28.
When is the first frost in Williamstown?
The first hard freeze (28°F) in Williamstown typically arrives around Nov 1, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 18, so the watching starts about Oct 2 — about 208 days after the spring freeze cleared.
How long is the growing season in Williamstown?
Measured between 28°F hard freezes, Williamstown sees about 208 frost-free days — roughly Apr 7 through Nov 1, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 28 to Oct 18, about 173 days.
Is the soil safe to grow vegetables in Williamstown?
The federal record around Williamstown is a meaningful one — 261 documented sites, mostly Nitrate entries (126), the nearest Underground Storage Tanks record about 0.3 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 Williamstown?
From about Oct 2 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 1 (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 1. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Williamstown's scale — its 6b band and its 208-day season. Your yard writes its own version of Williamstown'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 Williamstown’s own scale
7 of the readings below were taken at Williamstown's own scale — its own ~208-day season between 28°F freezes, the 166 acres it covers and 261 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Williamstown's own USDA hardiness band, zones 6bUSDA PHZM 2023
- Williamstown's own 28°F hard-freeze dates, about Apr 7 and Nov 1 and the ~208-day span between themNOAA 1991–2020 Climate Normals
- 261 documented contamination sites on the federal record near Williamstown, the closest Underground Storage Tanks record about 0.3 miles out from the town centreFederal environmental registers
- Williamstown's boundary and the 166 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6b and a ~208-day seasonGrowable Ground crop-matching engine
- The ecoregion at Williamstown's own centroid, the Ridge and ValleyUS EPA Level III Ecoregions
- A documented spotted-lanternfly record within reach of Williamstownlydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- Soil character — no town-scale survey exists, so Williamstown's 166 acres read through its county's SSURGO summaryfrom Dauphin County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Dauphin 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 Dauphin County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Williamstown's 166 acreswhy one lot differs from the next →
- Which side of Williamstown you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 166 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.3 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 Williamstown-wide figureread your own land →
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