Greenhorn, California, sits in USDA hardiness zone 7a — a zone band wide enough that plant choice, not possibility, is the interesting question.
A short list that earns its place here — cabbage, pawpaw, california poppy, and collard greens — with any one site's soil, sun, and drainage making the final cut.
Even in Greenhorn, 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 Greenhorn 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 Greenhorn — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Greenhorn — the short answer
Greenhorn, California: USDA zone 7a, about 185 days between hard freezes, across 4K acres of town.
- USDA zone
- 7a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 27
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 29
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~185
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 4K 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 Greenhorn's average, not your lot's — a low corner or a tree line moves it. Against Greenhorn's 185-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Greenhorn
Each reading below is measured for Greenhorn itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredGreenhorn 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
MeasuredGreenhorn 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 Greenhorn is in
Greenhorn sits in the Sierra Nevada — EPA Level III, inside the wider Northwestern Forested Mountains. That is read at Greenhorn's own centroid rather than borrowed from Plumas County.
What Grows in Greenhorn
Every plant below cleared Greenhorn's own zone 7a and its 185-day season. Each card opens that plant's California profile. How we score.
Is it too late to plant in Greenhorn?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Mar 30; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 27 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 29 — 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.
What's on the federal record near Greenhorn
Closest first, within ~10 miles of Greenhorn. Listing isn't leaking, and distance isn't exposure.
- UNION PACIFIC RAILROAD - KEDDIEBrownfields · 1.6 mi
- OhioMining · 2.4 mi
- SIERRA PACIFIC INDUSTRIESBrownfields · 4.9 mi
- Unnamed LocationMining · 4.9 mi
- Blue BellMining · 5.2 mi
- U.S. Smelting, Refining, and Mining Co.Mining · 5.6 mi
- U.S. SmeltingMining · 5.6 mi
- Us Smelting Refining & Mining CoMining · 5.7 mi
- Consolidated Gold and Metal Co.Mining · 5.9 mi
- Consolidated Gold & Metals CoMining · 5.9 mi
- WalkerMining · 6.2 mi
- Walker MineMining · 6.2 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Greenhorn'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 Greenhorn.
Total Sites
96
within ~10 miles of Greenhorn
Risk Level
Elevated
Highest-severity
4 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Greenhorn
Severity Distribution
within ~10 miles of Greenhorn
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Greenhorn, two things run higher than the national average within ~10 miles of Greenhorn — Mining (37 sites) and Superfund (4 sites). That's not a problem with your land — it's information about 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.
Superfund: Superfund sites represent the most severe contamination in the federal system.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Check your specific parcel in Greenhorn
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 Greenhorn average
Your land is one point inside Greenhorn
Everything above resolves to Greenhorn as a whole — one PHZM band and one 28°F frost record, read across 4K 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 Greenhorn Average
Greenhorn Average
- ●USDA Zones 7a, averaged across Greenhorn
- ●One soil character for all of Greenhorn
- ●Frost dates read at Greenhorn's scale: Apr 27 to Oct 29
YOUR Parcel
- ✓Your exact zone, not Greenhorn's 7a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Greenhorn
Pull a site-specific report for your exact address in Greenhorn, California — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Greenhorn averages can't show:
We read public map data around Greenhorn — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Greenhorn average
How we know this about Greenhorn
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 Greenhorn’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 Greenhorn
When does frost risk typically end in Greenhorn?
The last hard freeze (28°F) in Greenhorn typically lands around Apr 27, 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 18.
When is the first frost in Greenhorn?
The first hard freeze (28°F) in Greenhorn typically arrives around Oct 29, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 15, so the watching starts about Sep 29 — about 185 days after the spring freeze cleared.
How long is the growing season in Greenhorn?
Measured between 28°F hard freezes, Greenhorn sees about 185 frost-free days — roughly Apr 27 through Oct 29, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 18 to Oct 15, about 150 days.
Is the soil safe to grow vegetables in Greenhorn?
The federal record around Greenhorn is a meaningful one — 96 documented sites, mostly Brownfields entries (48), the nearest Brownfields record about 1.6 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 Greenhorn?
From about Sep 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 Oct 29 (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 29. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Greenhorn's scale — its 7a band and its 185-day season. Your yard writes its own version of Greenhorn'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 Greenhorn’s own scale
6 of the readings below were taken at Greenhorn's own scale — its own ~185-day season between 28°F freezes, the 4,295 acres it covers and 96 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Greenhorn's own USDA hardiness band, zones 7aUSDA PHZM 2023
- Greenhorn's own 28°F hard-freeze dates, about Apr 27 and Oct 29 and the ~185-day span between themNOAA 1991–2020 Climate Normals
- 96 documented contamination sites on the federal record near Greenhorn, the closest Brownfields record about 1.6 miles out from the town centreFederal environmental registers
- Greenhorn's boundary and the 4,295 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7a and a ~185-day seasonGrowable Ground crop-matching engine
- The ecoregion at Greenhorn's own centroid, the Sierra NevadaUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Greenhorn's 4,295 acres read through its county's SSURGO summaryfrom Plumas County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Plumas 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 Plumas County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Greenhorn's 4,295 acreswhy one lot differs from the next →
- Which side of Greenhorn you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 4,295 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Brownfields record about 1.6 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 Greenhorn-wide figureread your own land →