Sierra County, in California, sits in USDA hardiness zone 7a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
Reliable performers under these conditions include cabbage, blackberry, california poppy, and collard greens; what your own ground favors still comes down to its soil, sun, and drainage.
Sierra County lies within the Sierra Nevada Foothills — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Sierra County holds more than one microclimate.
Soils and elevations shift across Sierra County, so your frost dates and drainage aren't the county average. 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 Sierra County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Sierra County — the short answer
Sierra County, California: USDA zone 7a, about 138 days between hard freezes, across 610K acres.
- USDA zone
- 7a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 29
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 14
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~138
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 610K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are county 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 Sierra County's average, not your lot's — a low corner or a tree line moves it. Against Sierra County's 138-day season, see what your own ground reads.
Heat in Sierra County
Across a year, Sierra County accumulates about 1,093 growing degree days above 50°F, about 2,664 fewer than the middle California county — ahead of 2 of California’s 57 counties. Degree days are the heat a crop actually gets to work with — more of them is more room to ripen a long-season crop before the freeze closes the window.
Grounded in PRISM Climate Group, Oregon State University — 1991–2020 monthly normals
Soil in Sierra County
Across Sierra County, the ground is predominantly Inceptisols, where Waca, Deadwood, and Hurlbut are the most extensive named soil series. The soil is generally well drained with a gravelly sandy loam surface. Topsoil pH runs about 5.8–6.3, moderately acidic. Rainfall drains through hydrologic group D soils.
Soil order
Inceptisols
Drainage
Well drained
Hydric soils
1%
Soil still varies lot by lot — soil types explained.
How the ground varies across Sierra County
The USDA soil survey maps 61% of Sierra County as well drained — but another 32% drains differently: 15% somewhat excessively drained, 10% excessively drained.
Waca is the most extensive named soil at 9% of mapped acres, then Deadwood (8%) and Hurlbut (7%).
Which of them your own lot sits on is a parcel question, not a county one. Check your address for the survey at your boundary.
What this means for growing in Sierra County
Each reading below is measured for Sierra County itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Drainage
MeasuredThe dominant soils across Sierra County are well drained, in hydrologic group D — ground that drains quickly.
The upside is soil you can work early in spring and roots that never drown; the cost is that fast-draining ground dries out fast and leaches nutrients away before plants can use them.
Work in compost and mulch to hold moisture and feed, and water more often in short doses than deep and rarely.
USDA NRCS SSURGO
Surface pH
MeasuredTopsoil across Sierra County runs about pH 5.8–6.3, close to neutral.
This is the range most vegetables prefer — one correction you probably do not have to make, which is genuinely good news for a new bed.
Keep it there with compost rather than lime or sulfur, and only amend if your own soil test says otherwise.
USDA NRCS SSURGO
Season length
MeasuredSierra County runs about 138 days between hard freezes — a short growing season.
Long-maturing crops like melons, sweet potatoes, and winter squash can run out of runway before the first hard freeze, ripening late or not at all.
Lead with fast-maturing varieties, and stretch the season on both ends with cold frames, low tunnels, or a greenhouse.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredSierra County 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 Sierra County is in
Sierra County spans 2 EPA Level III ecoregions — Sierra Nevada (92%) and Central Basin and Range (8%). Which one your land falls in changes what grows wild there and how the ground behaves, and a county-wide answer cannot tell you which.
What Grows in Sierra County
We scored all 1,086 plants against Sierra County's own USDA zone 7a and its own 138-day season between hard freezes, using the same matching engine that runs a full parcel report. These cleared both. Sun, soil pH and drainage vary lot by lot — those are the parcel questions below. Each card opens that plant's California profile.
Is it too late to plant in Sierra County?
Rarely: the season closes in stages, not all at once, and each stage has its crops. Cool-season crops can go in from around May 1; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 29 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 14 — long-season crops need about 90 days of runway, quick greens only 30. In a season this compact, fast finishers and cold-hardy greens do the late work, and garlic tucked in before the freeze repays you next summer.
Documented around Sierra County
- monarch butterfly19 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Sierra County
USGS estimates 190 lb of Glyphosate on Sierra County farmland in 2019, its largest by weight, ahead of Metribuzin (148 lb) and 2,4-d (143 lb).
Farmland across the whole county, not any one lot. Check your address for the site-by-site record.
Safe to Grow Here?
What the federal record shows across Sierra County — and how to grow with it.
We checked the federal record across Sierra County — 125 documented sites across 4 of the 9 source types we track.
The most significant on record: 1 Toxics Release Inventory facility. Active industrial facilities reporting chemical releases to air, water, and land.
Sierra County carries one of the heavier federal records we track — and that's not a verdict on your yard. Proximity to a documented site is information, not a diagnosis: nothing here says any particular parcel is affected. It does earn one concrete step — before food beds go in the ground, a professional soil test tells you exactly what you're working with, and raised beds with clean imported soil grow well almost anywhere in the meantime.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Sierra County
Closest first, across Sierra County. Listing isn't leaking, and distance isn't exposure.
- ZuvarMining · 1.9 mi
- Hapgood & MillerMining · 2.0 mi
- Hapgood and MillerMining · 2.0 mi
- Copper MineMining · 3.2 mi
- OccurrenceMining · 3.4 mi
- Basset PrideMining · 3.9 mi
- SIERRA COUNTY/EMERGENCY RESPONSE ONLYBrownfields · 4.4 mi
- SIERRA COUNTY DEPT PUB WORKSBrownfields · 4.4 mi
- Sierra HomestakeMining · 4.4 mi
- EIF HAYPRESS LLCBrownfields · 4.8 mi
- PhoenixMining · 5.4 mi
- PACIFIC BELL TELEPHONE COMPANYBrownfields · 5.9 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Sierra County'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 Sierra County.
Sources Checked
across Sierra County
Severity Distribution
across Sierra County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Sierra County, Mining runs higher than the national average — 93 sites across Sierra County. 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.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Check your specific parcel in Sierra County
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 Sierra County average
Your land is one point inside Sierra County
Everything above resolves to Sierra County as a whole — one PHZM band and one county frost record, read across 610K 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 county 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 county average.
Your Lot vs the Sierra County Average
Sierra County Average
- ●USDA Zones 7a, averaged across Sierra County
- ●One soil character for all of Sierra County
- ●Frost dates read at Sierra County's scale: May 29 to Oct 14
YOUR Parcel
- ✓Your exact zone, not Sierra County's 7a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Sierra County
Pull a site-specific report for your exact address in Sierra County, California — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Sierra County averages can't show:
We read public map data around Sierra County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Sierra County average
How we know this about Sierra County
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at county grain; hard-freeze dates from NOAA 1991–2020 28°F normals at this county’s own record where one resolves, and the labelled statewide window where none does; soils from the USDA NRCS SSURGO survey, area-weighted across the county’s own map units; boundaries and acreage from US Census TIGER/Line 2025; the contamination and pesticide records from the federal sources named in their beats above. Where Sierra County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Sierra County
When does frost risk typically end in Sierra County?
The last hard freeze (28°F) in Sierra County typically lands around May 29, 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 Jun 19.
How long is the growing season in Sierra County?
Measured between 28°F hard freezes, Sierra County sees about 138 frost-free days — roughly May 29 through Oct 14, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Jun 19 to Sep 30, about 103 days.
Is the soil safe to grow vegetables in Sierra County?
The federal record around Sierra County runs heavier than most — 125 documented sites, mostly Mining entries (93), the nearest Mining record about 1.9 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 gardeners stretch the season in Sierra County?
With about 138 frost-free days between hard freezes, Sierra County rewards the classic extension moves: floating row cover buys roughly two to four extra weeks at each shoulder — on this season that is a working window nearer 166 to 194 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the May 29 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Sierra County's scale — its 7a band and its 138-day season. Your yard writes its own version of Sierra County's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
Will It Grow Here?
Zone fit is the first question — each answer below reads California's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Sierra County’s own scale
9 of the readings below were taken at Sierra County's own scale — its own ~138-day span between 28°F freezes, the 3 most extensive soil series mapped here and 125 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Sierra County's own USDA hardiness band, zones 7aUSDA PHZM 2023
- Sierra County's own 28°F hard-freeze dates and its ~138-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Sierra CountyUSDA NRCS SSURGO
- 125 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Mining record about 1.9 miles outFederal environmental registers
- Sierra County's boundary and the 610,027 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7a and a ~138-day seasonGrowable Ground crop-matching engine
- The 2 ecoregions Sierra County spans, Sierra Nevada the largestUS EPA Level III Ecoregions
- Open occurrence records documented in Sierra County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Sierra County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every California grower plans around — written at state scale, so they stay on the state guidefrom California
What this page can’t tell you
- How the season shifts across Sierra County — the ~138 days above is one reading at its centre; the 12 towns below each carry their owntowns in this county →
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Sierra County's 610,027 acreswhy one lot differs from the next →
- Which of those 125 documented sites actually reaches your soil — that needs your address, the wind, and the groundwater directionhow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — none of it survives being averaged over Sierra Countyread your own land →