Mariposa County, in California, sits in USDA hardiness zone 8b — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
Well-matched crops include cabbage, fig, california poppy, and collard greens, and the gap between "grows in the area" and "grows in your yard" is closed by soil, sun, and drainage.
Mariposa 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
Mariposa County holds more than one microclimate.
Soils and elevations shift across Mariposa 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 Mariposa County — soil, climate, flood, and parcel records. How we handle your address.
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Mariposa County — the short answer
Mariposa County, California: USDA zone 8b, about 249 days between hard freezes, across 927K acres.
- USDA zone
- 8b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 20
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Nov 24
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~249
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 927K 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 8b is Mariposa County's average, not your lot's — a low corner or a tree line moves it. Against Mariposa County's 249-day season, see what your own ground reads.
Heat and winter chill in Mariposa County
Across a year, Mariposa County accumulates about 3,579 growing degree days above 50°F, about 178 fewer than the middle California county — ahead of 24 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.
Winter banks about 1,889 hours below 45°F, 702 more than the California middle of 1,187. Chill is what tells a fruit tree its dormancy is over, and it is set by climate rather than by anything you can build.
Grounded in PRISM Climate Group, Oregon State University — 1991–2020 monthly normals
Soil in Mariposa County
Across Mariposa County, the ground is predominantly Alfisols, where Daulton, Canisrocks, and Gopheridge are the most extensive named soil series. The soil is generally well drained with a loam surface. Topsoil pH runs about 5.8–6.2, moderately acidic. Rainfall drains through hydrologic group D soils.
Soil order
Alfisols
Drainage
Well drained
Hydric soils
0%
Soil still varies lot by lot — soil types explained.
How the ground varies across Mariposa County
The USDA soil survey maps 56% of Mariposa County as well drained — but another 34% drains differently: 21% somewhat excessively drained, 13% excessively drained.
Daulton is the most extensive named soil at 4% of mapped acres, then Canisrocks (4%) and Gopheridge (3%).
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 Mariposa County
Each reading below is measured for Mariposa 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 Mariposa 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 Mariposa County runs about pH 5.8–6.2, 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
MeasuredMariposa County runs about 249 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
MeasuredMariposa County sits in USDA hardiness zone 8b.
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 Mariposa County is in
Mariposa County spans 2 EPA Level III ecoregions — Sierra Nevada (58%) and Central California Foothills and Coastal Mountains (42%). 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 Mariposa County
We scored all 1,086 plants against Mariposa County's own USDA zone 8b and its own 249-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 Mariposa County?
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 Feb 20; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 20 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 24 — 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.
Documented around Mariposa County
- monarch butterfly62 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Mariposa County
USGS estimates 484 lb of Glyphosate on Mariposa County farmland in 2019, its largest by weight, ahead of Triclopyr (159 lb) and Imidacloprid (1 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 Mariposa County — and how to grow with it.
We checked the federal record across Mariposa County — 305 documented sites across 7 of the 9 source types we track.
The most significant on record: 5 Superfund sites (none NPL-listed). Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Mariposa 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 Mariposa County
Closest first, across Mariposa County. Listing isn't leaking, and distance isn't exposure.
- FelicianaMining · 1.4 mi
- Midpines Food And GasUnderground Storage Tanks · 1.7 mi
- CAL TRANSBrownfields · 1.7 mi
- EarlyMining · 2.0 mi
- White OakMining · 3.3 mi
- LandrumMining · 3.8 mi
- Champion IiMining · 3.9 mi
- BRAND AUTOMOTIVE SERVICEBrownfields · 3.9 mi
- Our ChanceMining · 5.3 mi
- DiltzMining · 5.4 mi
- LeachMining · 5.5 mi
- Lonesome PineMining · 5.5 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Mariposa 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 Mariposa County.
Total Sites
305
across Mariposa County
Risk Level
High
Highest-severity
5 Superfund sites (none NPL-listed)
Sources Checked
across Mariposa County
Severity Distribution
across Mariposa County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Mariposa County, two things run higher than the national average across Mariposa County — Mining (168 sites) and Superfund (5 sites). Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
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 Mariposa 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 Mariposa County average
Your land is one point inside Mariposa County
Everything above resolves to Mariposa County as a whole — one PHZM band and one county frost record, read across 927K 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 Mariposa County Average
Mariposa County Average
- ●USDA Zones 8b, averaged across Mariposa County
- ●One soil character for all of Mariposa County
- ●Frost dates read at Mariposa County's scale: Mar 20 to Nov 24
YOUR Parcel
- ✓Your exact zone, not Mariposa County's 8b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Mariposa County
Pull a site-specific report for your exact address in Mariposa County, California — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Mariposa County averages can't show:
We read public map data around Mariposa County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Mariposa County average
How we know this about Mariposa 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 Mariposa County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Mariposa County
When does frost risk typically end in Mariposa County?
The last hard freeze (28°F) in Mariposa County typically lands around Mar 20, 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 10.
How long is the growing season in Mariposa County?
Measured between 28°F hard freezes, Mariposa County sees about 249 frost-free days — roughly Mar 20 through Nov 24, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 10 to Nov 10, about 214 days.
Is the soil safe to grow vegetables in Mariposa County?
The federal record around Mariposa County runs heavier than most — 305 documented sites, mostly Mining entries (168), the nearest Mining record about 1.4 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.
Everything above is measured at Mariposa County's scale — its 8b band and its 249-day season. Your yard writes its own version of Mariposa 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 Mariposa County’s own scale
9 of the readings below were taken at Mariposa County's own scale — its own ~249-day span between 28°F freezes, the 3 most extensive soil series mapped here and 305 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Mariposa County's own USDA hardiness band, zones 8bUSDA PHZM 2023
- Mariposa County's own 28°F hard-freeze dates and its ~249-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Mariposa CountyUSDA NRCS SSURGO
- 305 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Mining record about 1.4 miles outFederal environmental registers
- Mariposa County's boundary and the 927,256 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 8b and a ~249-day seasonGrowable Ground crop-matching engine
- The 2 ecoregions Mariposa County spans, Sierra Nevada the largestUS EPA Level III Ecoregions
- Open occurrence records documented in Mariposa County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Mariposa 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 Mariposa County — the ~249 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 Mariposa County's 927,256 acreswhy one lot differs from the next →
- Which of those 305 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 Mariposa Countyread your own land →