Penngrove, California, sits in USDA hardiness zone 9a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
A short list that earns its place here — artichoke, fig, california poppy, and cabbage — with any one site's soil, sun, and drainage making the final cut.
Even in Penngrove, 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 Penngrove 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 Penngrove — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Penngrove — the short answer
Penngrove, California: USDA zone 9a, about 323 days between hard freezes, across 3K acres of town.
- USDA zone
- 9a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Jan 23
- Sonoma County normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Dec 12
- Sonoma County normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~323
- Sonoma County normal — NOAA 1991–2020, nearest to this town
- Town area
- 3K 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 Sonoma County’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 9a is Penngrove's average, not your lot's — a low corner or a tree line moves it. Against Penngrove's 323-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Penngrove
Each reading below is measured for Penngrove itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsPenngrove runs about 323 days between hard freezes (read from Sonoma County, the closest normal to Penngrove) — close to year-round growing.
Frost is rarely the limit here; winter plantings are as real as summer ones, and the harder question is which crops shrug off the summer heat.
Grow cool-season crops through the mild winter, and choose heat-tolerant varieties for the summer beds.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredPenngrove sits in USDA hardiness zone 9a.
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 Penngrove is in
Penngrove sits in the Central California Foothills and Coastal Mountains — EPA Level III, inside the wider Mediterranean California. That is read at Penngrove's own centroid rather than borrowed from Sonoma County.
What Grows in Penngrove
Every plant below cleared Penngrove's own zone 9a and its 323-day season. Each card opens that plant's California profile. How we score.
Is it too late to plant in Penngrove?
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 Jan 1; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Jan 23 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 12 — long-season crops need about 90 days of runway, quick greens only 30. In a climate this gentle, “too late” hardly applies — the question becomes which crops prefer the cooler months ahead.
What's on the federal record near Penngrove
Closest first, within ~10 miles of Penngrove. Listing isn't leaking, and distance isn't exposure.
- V DOLAN TRUCKINGBrownfields · 600 ft
- PACIFIC BELLBrownfields · 800 ft
- SONOMA COUNTYBrownfields · 1100 ft
- PENNGROVE MOTORCYCLE COMPANY 9585Brownfields · 1400 ft
- JAMES PIAZZA - 6040 OLD REDWOOD HIGHWAYBrownfields · 1400 ft
- PENNGROVEBrownfields · 1900 ft
- S.C. PHILLIPS ENTERPRISES LLCBrownfields · 2000 ft
- KEVIN SCARPETE TRUCKINGBrownfields · 0.6 mi
- JEFF'S TWIN OAKS GARAGEBrownfields · 0.7 mi
- 005N008W12A001MNitrate · 0.9 mi
- THOMAS & JENNIFER LUCHESEBrownfields · 1.0 mi
- WILLOWBROOK FEEDSBrownfields · 1.2 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Penngrove'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 Penngrove.
Sources Checked
within ~10 miles of Penngrove
Severity Distribution
within ~10 miles of Penngrove
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Penngrove, Brownfields runs higher than the national average — 1,355 sites within ~10 miles of Penngrove. It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Brownfields: Brownfield sites are former commercial or industrial properties where legacy soil contamination (heavy metals, PAHs, petroleum compounds) may persist.
Check EPA brownfield remediation status — many sites have completed cleanup with institutional controls.
Check your specific parcel in Penngrove
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 Penngrove average
Your land is one point inside Penngrove
Everything above resolves to Penngrove as a whole — one PHZM band, read across 3K acres, with hard-freeze dates borrowed from Sonoma 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 Penngrove Average
Penngrove Average
- ●USDA Zones 9a, averaged across Penngrove
- ●One soil character for all of Penngrove
- ●Frost dates read at Penngrove's scale: Jan 23 to Dec 12
YOUR Parcel
- ✓Your exact zone, not Penngrove's 9a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Penngrove
Pull a site-specific report for your exact address in Penngrove, California — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Penngrove averages can't show:
We read public map data around Penngrove — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Penngrove average
How we know this about Penngrove
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 Sonoma 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 Penngrove
When does frost risk typically end in Penngrove?
The last hard freeze (28°F) in Penngrove typically lands around Jan 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 Feb 13.
When is the first frost in Penngrove?
The first hard freeze (28°F) in Penngrove typically arrives around Dec 12, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 28, so the watching starts about Nov 12 — about 323 days after the spring freeze cleared.
How long is the growing season in Penngrove?
Measured between 28°F hard freezes, Penngrove sees about 323 frost-free days — roughly Jan 23 through Dec 12, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Feb 13 to Nov 28, about 288 days.
Is the soil safe to grow vegetables in Penngrove?
The federal record around Penngrove is a meaningful one — 1,570 documented sites, mostly Brownfields entries (1,355), the nearest Brownfields record about 0.1 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 Penngrove?
From about Nov 12 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 Dec 12 (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 Dec 12. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Penngrove's scale — its 9a band and its 323-day season. Your yard writes its own version of Penngrove'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 Penngrove’s own scale
5 of the readings below were taken at Penngrove's own scale — the 2,582 acres it covers and 1,570 documented sites around it; 5 are borrowed from a wider read, named and linked below.
Measured here
- Penngrove's own USDA hardiness band, zones 9aUSDA PHZM 2023
- 1,570 documented contamination sites on the federal record near Penngrove, the closest Brownfields record about 0.1 miles out from the town centreFederal environmental registers
- Penngrove's boundary and the 2,582 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9a and a ~323-day seasonGrowable Ground crop-matching engine
- The ecoregion at Penngrove's own centroid, the Central California Foothills and Coastal MountainsUS EPA Level III Ecoregions
Inherited from a wider read
- The 28°F hard-freeze dates — Penngrove has no normal of its own, so its county's is the closest measured readfrom Sonoma County
- Soil character — no town-scale survey exists, so Penngrove's 2,582 acres read through its county's SSURGO summaryfrom Sonoma County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Sonoma 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 Sonoma County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Penngrove's 2,582 acreswhy one lot differs from the next →
- Which side of Penngrove you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 2,582 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Brownfields record about 0.1 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 Penngrove-wide figureread your own land →
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