Modoc County, in California, sits in USDA hardiness zone 7a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
Well-matched crops include cabbage, pawpaw, 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.
Modoc County lies within the Klamath Basin — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Modoc County holds more than one microclimate.
Soils and elevations shift across Modoc 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 Modoc County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Modoc County — the short answer
Modoc County, California: USDA zone 7a, about 164 days between hard freezes, across 2.5M acres.
- USDA zone
- 7a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 4
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 15
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~164
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 2.5M 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 Modoc County's average, not your lot's — a low corner or a tree line moves it. Against Modoc County's 164-day season, see what your own ground reads.
One county, several growing seasons
Modoc County's hard-freeze record runs about 164 days between freezes — but that is the county-wide average, and several towns inside it carry a markedly different season in their own 30-year record: Daphnedale Park at about 131 days (against the county's ~164).
Those are measured records, not estimates. If you garden in one of these pockets, plant against your own town's season rather than the county's ~164-day average.
NOAA Regional Climate Centers ACIS (1991–2020), 30-year daily minimum record. Only held-out towns carrying their own record are named — a town with no record of its own is absent rather than estimated, and a county with nothing qualifying shows no spread at all.
Heat in Modoc County
Across a year, Modoc County accumulates about 1,616 growing degree days above 50°F, about 2,141 fewer than the middle California county — ahead of 5 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 Modoc County
Across Modoc County, the ground is predominantly Mollisols, where Jimmerson, Deven, and Karcal are the most extensive named soil series. The soil is generally well drained with a sandy loam surface. Topsoil pH runs about 6.5–7.2, neutral. Rainfall drains through hydrologic group D soils.
Soil order
Mollisols
Drainage
Well drained
Hydric soils
8%
Soil still varies lot by lot — soil types explained.
How the ground varies across Modoc County
The USDA soil survey maps 69% of Modoc County as well drained — but another 22% drains differently: 5% moderately well drained, 5% poorly drained.
Jimmerson is the most extensive named soil at 3% of mapped acres, then Deven (3%) and Karcal (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 Modoc County
Each reading below is measured for Modoc 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 Modoc 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 Modoc County runs about pH 6.5–7.2, 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
MeasuredModoc County runs about 164 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
MeasuredModoc 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 Modoc County is in
Modoc County spans 2 EPA Level III ecoregions — Eastern Cascades Slopes and Foothills (86%) and Northern Basin and Range (11%). 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 Modoc County
We scored all 1,086 plants against Modoc County's own USDA zone 7a and its own 164-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 Modoc 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 Apr 6; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 4 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 15 — long-season crops need about 90 days of runway, quick greens only 30. Even past midsummer there is room for a true fall garden here, and garlic planted near the close carries the momentum into next year.
Documented around Modoc County
- monarch butterfly1 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Modoc County
USGS estimates 8,180 lb of Glyphosate on Modoc County farmland in 2019, its largest by weight, ahead of Metribuzin (6,386 lb) and 2,4-d (5,400 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 Modoc County — and how to grow with it.
We checked the federal record across Modoc County — 117 documented sites across 5 of the 9 source types we track.
The most significant on record: 1 Superfund site (none NPL-listed). Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
There's a meaningful federal record across Modoc County — worth a look before you plant food, not a reason to hold back from growing. Proximity to a documented site is information, not a diagnosis of any one yard. A soil test before new food beds is the sensible precaution here, and the map shows exactly which sites sit where, so you can see what's actually near you.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Modoc County
Closest first, across Modoc County. Listing isn't leaking, and distance isn't exposure.
- 043N011E35F001MNitrate · 5.3 mi
- DSLR LLC DBA SX LOWRY RANCHBrownfields · 9.6 mi
- NORTH STATE GROCERY INC DBA HOLIDAY MARKETBrownfields · 10.6 mi
- CHARTER COMMUNICATIONS-ALTURASBrownfields · 11.0 mi
- MODOC COUNTY ROAD DEPARTMENT - ALTURAS SHOPBrownfields · 11.0 mi
- SAGE COUNTRY RECYCLING INC DBA SAGE COUNTRY RECYCLINGBrownfields · 11.1 mi
- BLUE WATER RECYCLING CORPBrownfields · 11.1 mi
- DOHS-MODOC COBrownfields · 11.2 mi
- ED STAUB & SONS PETROLEUM, INC. - ALTURAS BULK PLANTBrownfields · 11.2 mi
- Modoc Mini-MartUnderground Storage Tanks · 11.3 mi
- MODOC CO DEPT OF AGRIBrownfields · 11.3 mi
- DOLLAR GENERAL #14747Brownfields · 11.3 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Modoc 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 Modoc County.
Total Sites
117
across Modoc County
Risk Level
Elevated
Highest-severity
1 Superfund site (none NPL-listed)
Sources Checked
across Modoc County
Severity Distribution
across Modoc County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Modoc County, two things run higher than the national average across Modoc County — Mining (26 sites) and Brownfields (57 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.
Brownfields: Brownfield sites are former commercial or industrial properties where legacy soil contamination (heavy metals, PAHs, petroleum compounds) may persist.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Check EPA brownfield remediation status — many sites have completed cleanup with institutional controls.
Check your specific parcel in Modoc 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 Modoc County average
Your land is one point inside Modoc County
Everything above resolves to Modoc County as a whole — one PHZM band and one county frost record, read across 2.5M 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 Modoc County Average
Modoc County Average
- ●USDA Zones 7a, averaged across Modoc County
- ●One soil character for all of Modoc County
- ●Frost dates read at Modoc County's scale: May 4 to Oct 15
YOUR Parcel
- ✓Your exact zone, not Modoc County's 7a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Modoc County
Pull a site-specific report for your exact address in Modoc County, California — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Modoc County averages can't show:
We read public map data around Modoc County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Modoc County average
How we know this about Modoc 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 Modoc County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Modoc County
When does frost risk typically end in Modoc County?
The last hard freeze (28°F) in Modoc County typically lands around May 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 May 25.
How long is the growing season in Modoc County?
Measured between 28°F hard freezes, Modoc County sees about 164 frost-free days — roughly May 4 through Oct 15, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 25 to Oct 1, about 129 days.
Is the soil safe to grow vegetables in Modoc County?
The federal record around Modoc County is a meaningful one — 117 documented sites, mostly Brownfields entries (57), the nearest Nitrate record about 5.3 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.
Everything above is measured at Modoc County's scale — its 7a band and its 164-day season. Your yard writes its own version of Modoc 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 Modoc County’s own scale
9 of the readings below were taken at Modoc County's own scale — its own ~164-day span between 28°F freezes, the 3 most extensive soil series mapped here and 117 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Modoc County's own USDA hardiness band, zones 7aUSDA PHZM 2023
- Modoc County's own 28°F hard-freeze dates and its ~164-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Modoc CountyUSDA NRCS SSURGO
- 117 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Nitrate record about 5.3 miles outFederal environmental registers
- Modoc County's boundary and the 2,526,867 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7a and a ~164-day seasonGrowable Ground crop-matching engine
- The 2 ecoregions Modoc County spans, Eastern Cascades Slopes and Foothills the largestUS EPA Level III Ecoregions
- Open occurrence records documented in Modoc County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Modoc 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 Modoc County — the ~164 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 Modoc County's 2,526,867 acreswhy one lot differs from the next →
- Which of those 117 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 Modoc Countyread your own land →