Penn Valley, California, sits in USDA hardiness zone 9b — a zone band wide enough that plant choice, not possibility, is the interesting question.
Well-matched crops include tomato, artichoke, fig, and california poppy, and the gap between "grows in the area" and "grows in your yard" is closed by soil, sun, and drainage.
Even in Penn Valley, 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 Penn Valley 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 Penn Valley — soil, climate, flood, and parcel records. How we handle your address.
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Penn Valley — the short answer
Penn Valley, California: USDA zone 9b, about 238 days between hard freezes, across 1K acres of town.
- USDA zone
- 9b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 4
- Nevada County normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Nov 28
- Nevada County normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~238
- Nevada County normal — NOAA 1991–2020, nearest to this town
- Town area
- 1K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. No 30-year normal resolves at this town’s own centroid, so the hard-freeze dates are Nevada County’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 9b is Penn Valley's average, not your lot's — a low corner or a tree line moves it. Against Penn Valley's 238-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Penn Valley
Each reading below is measured for Penn Valley itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsPenn Valley runs about 238 days between hard freezes (read from Nevada County, the closest normal to Penn Valley) — 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
MeasuredPenn Valley sits in USDA hardiness zone 9b.
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 Penn Valley is in
Penn Valley sits in the Central California Foothills and Coastal Mountains — EPA Level III, inside the wider Mediterranean California. That is read at Penn Valley's own centroid, and it is not what its county reads: Nevada County is mostly Sierra Nevada. The wider page above you is answering a different question about different ground.
What Grows in Penn Valley
Plants matched to Penn Valley's USDA zones 9b, ordered by how much hardiness margin each has here — the ones with room to spare at both ends of this town's band lead. Each links to its full growing profile.
Is it too late to plant in Penn Valley?
Rarely: the season closes in stages, not all at once, and each stage has its crops. Cool-season crops can go in from around Mar 7; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 4 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 28 — 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.
What's on the federal record near Penn Valley
Closest first, within ~10 miles of Penn Valley. Listing isn't leaking, and distance isn't exposure.
- D-868Brownfields · 2500 ft
- Penn Valley Mini MartUnderground Storage Tanks · 0.9 mi
- PENN VALLEY MINI MARTBrownfields · 0.9 mi
- TaylorMining · 0.9 mi
- EAGLE QUICK LUBEBrownfields · 0.9 mi
- GUTIERREZ PENN VALLEY ENT PENN VALLEY TRUE VALUE HARDWAREBrownfields · 0.9 mi
- PENN VALLEY FIRE PROTECTION DISTRICTBrownfields · 0.9 mi
- PENN VALLEY SERVICE INCBrownfields · 0.9 mi
- Sierra Energy #16Underground Storage Tanks · 1.0 mi
- TOMS SIERRA CO. LOCATION #16Brownfields · 1.0 mi
- PLAZA TIRE AND AUTO SERVICE, LLC.Brownfields · 1.0 mi
- KV STRUCTURES INCBrownfields · 1.2 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Penn Valley'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 Penn Valley.
Total Sites
543
within ~10 miles of Penn Valley
Risk Level
High
Highest-severity
3 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Penn Valley
Severity Distribution
within ~10 miles of Penn Valley
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Penn Valley, two things run higher than the national average within ~10 miles of Penn Valley — Mining (170 sites) and PFAS (6 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Mining: Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease.
PFAS: PFAS (per- and polyfluoroalkyl substances) are called "forever chemicals" because they do not biodegrade.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Test irrigation water source — this is the primary pathway for PFAS to reach garden crops.
Check your specific parcel in Penn Valley
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 Penn Valley average
Your land is one point inside Penn Valley
Everything above resolves to Penn Valley as a whole — one PHZM band, read across 1K acres, with hard-freeze dates borrowed from Nevada County’s record because no 30-year normal resolves at this town’s own centroid. 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 Penn Valley Average
Penn Valley Average
- ●USDA Zones 9b, averaged across Penn Valley
- ●One soil character for all of Penn Valley
- ●Frost dates read at Penn Valley's scale: Apr 4 to Nov 28
YOUR Parcel
- ✓Your exact zone, not Penn Valley's 9b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Penn Valley
Pull a site-specific report for your exact address in Penn Valley, California — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Penn Valley averages can't show:
We read public map data around Penn Valley — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Penn Valley average
How we know this about Penn Valley
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 Nevada County’s record, because none resolves here; 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 Penn Valley
When does frost risk typically end in Penn Valley?
The last hard freeze (28°F) in Penn Valley typically lands around Apr 4, 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 25.
When is the first frost in Penn Valley?
The first hard freeze (28°F) in Penn Valley typically arrives around Nov 28, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 14, so the watching starts about Oct 29 — about 238 days after the spring freeze cleared.
How long is the growing season in Penn Valley?
Measured between 28°F hard freezes, Penn Valley sees about 238 frost-free days — roughly Apr 4 through Nov 28, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 25 to Nov 14, about 203 days.
Is the soil safe to grow vegetables in Penn Valley?
The federal record around Penn Valley runs heavier than most — 543 documented sites, mostly Brownfields entries (297), the nearest Brownfields record about 0.5 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 Penn Valley?
From about Oct 29 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 28 (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 28. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Penn Valley's scale — its 9b band and its 238-day season. Your yard writes its own version of Penn Valley'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 Penn Valley’s own scale
4 of the readings below were taken at Penn Valley's own scale — the 1,357 acres it covers and 543 documented sites around it; 6 are borrowed from a wider read, named and linked below.
Measured here
- Penn Valley's own USDA hardiness band, zones 9bUSDA PHZM 2023
- 543 documented contamination sites on the federal record near Penn Valley, the closest Brownfields record about 0.5 miles out from the town centreFederal environmental registers
- Penn Valley's boundary and the 1,357 acres inside itUS Census TIGER/Line 2025
- Penn Valley sits in the Central California Foothills and Coastal Mountains — not the ecoregion its county mostly readsUS EPA Level III Ecoregions
Inherited from a wider read
- The 28°F hard-freeze dates — Penn Valley has no normal of its own, so its county's is the closest measured readfrom Nevada County
- Soil character — no town-scale survey exists, so Penn Valley's 1,357 acres read through its county's SSURGO summaryfrom Nevada County
- The candidate plant list — California's curated set, filtered to this zone band and re-ordered by how much margin each has herefrom California
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Nevada County
- The growing challenges every California grower plans around — written at state scale, so they stay on the state guidefrom California
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Nevada County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Penn Valley's 1,357 acreswhy one lot differs from the next →
- Which side of Penn Valley you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 1,357 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Brownfields record about 0.5 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 Penn Valley-wide figureread your own land →