San Joaquin County, in California, sits in USDA hardiness zone 9b — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
Among the crops suited to this profile: okra, meyer lemon, california poppy, and artichoke. The site-level story — soil, sun, drainage — decides the rest.
San Joaquin County lies within Lodi and the California Delta — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
San Joaquin County holds more than one microclimate.
Soils and elevations shift across San Joaquin 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 San Joaquin County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
San Joaquin County — the short answer
San Joaquin County, California: USDA zone 9b, about 321 days between hard freezes, across 891K acres.
- USDA zone
- 9b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Jan 24
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Dec 11
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~321
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 891K 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 9b is San Joaquin County's average, not your lot's — a low corner or a tree line moves it. Against San Joaquin County's 321-day season, see what your own ground reads.
Heat and winter chill in San Joaquin County
Across a year, San Joaquin County accumulates about 4,290 growing degree days above 50°F, about 533 more than the middle California county — ahead of 34 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 1,092 hours below 45°F, 95 fewer 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 San Joaquin County
Across San Joaquin County, the ground is predominantly Mollisols, where Capay, Rindge, and Tokay are the most extensive named soil series. The soil is generally well drained with a clay loam surface. Topsoil pH runs about 6.3–7.5, neutral. Rainfall drains through hydrologic group C soils.
Soil order
Mollisols
Drainage
Well drained
Hydric soils
35%
Soil still varies lot by lot — soil types explained.
How the ground varies across San Joaquin County
The USDA soil survey maps 31% of San Joaquin County as well drained — but another 66% drains differently: 27% moderately well drained, 14% somewhat poorly drained.
Capay is the most extensive named soil at 5% of mapped acres, then Rindge (4%) and Tokay (4%).
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 San Joaquin County
Each reading below is measured for San Joaquin 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 San Joaquin County are well drained, in hydrologic group C — 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 San Joaquin County runs about pH 6.3–7.5, 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
Wet ground
MeasuredAbout 35% of San Joaquin County is mapped as hydric — wetland — soil.
If your lot falls in one of those pockets, a standard in-ground bed will fight waterlogging all season, and roots that need air will struggle.
Check how your own ground drains before you dig; raised beds or moisture-loving plantings turn a wet corner from a problem into a niche.
USDA NRCS SSURGO
Season length
MeasuredSan Joaquin County runs about 321 days between hard freezes — 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
The kind of country San Joaquin County is in
San Joaquin County spans 2 EPA Level III ecoregions — Central California Valley (89%) and Central California Foothills and Coastal Mountains (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 San Joaquin County
We scored all 1,086 plants against San Joaquin County's own USDA zone 9b and its own 321-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 San Joaquin County?
For most of the year, no — what changes is which crops still fit the days remaining. 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 24 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 11 — long-season crops need about 90 days of runway, quick greens only 30. Here the calendar nearly circles: cool-season crops take the winter shift, and the next window is always close.
Documented around San Joaquin County
- monarch butterfly2 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in San Joaquin County
USGS estimates 518,657 lb of Glyphosate on San Joaquin County farmland in 2019, its largest by weight, ahead of Metolachlor & Metolachlor-s (38,386 lb) and Methoxyfenozide (34,991 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 San Joaquin County — and how to grow with it.
We checked the federal record across San Joaquin County — 5,304 documented sites across 8 of the 9 source types we track.
The most significant on record: 9 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
San Joaquin 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 San Joaquin County
Closest first, across San Joaquin County. Listing isn't leaking, and distance isn't exposure.
- MOCTEZUMAS AUTO DISMANTLERBrownfields · 900 ft
- TORRES CARDASO TRUCKINGBrownfields · 1400 ft
- J.R. SIMPLOT COMPANYBrownfields · 1500 ft
- CHS OILSEED PROCESSINGBrownfields · 1500 ft
- UNION PACIFIC RAILROADBrownfields · 1500 ft
- CITY OF STOCKTON FIRE STATION #3Brownfields · 1700 ft
- AMAZON.COM SERVICES LLC - SMF3Brownfields · 1900 ft
- PAQ INC. DBA/RANCHO SAN MIGUELBrownfields · 2100 ft
- RANCHO SAN MIGUEL MARKET*Underground Storage Tanks · 2200 ft
- MOE AUTO REPAIRBrownfields · 2200 ft
- ULTRAMAR INCBrownfields · 2200 ft
- EL PRIMO AUTO DISMANTLEBrownfields · 2300 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from San Joaquin 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 San Joaquin County.
Sources Checked
across San Joaquin County
Severity Distribution
across San Joaquin County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around San Joaquin County, Brownfields runs higher than the national average — 3,827 sites across San Joaquin County. Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
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 San Joaquin 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 San Joaquin County average
Your land is one point inside San Joaquin County
Everything above resolves to San Joaquin County as a whole — one PHZM band and one county frost record, read across 891K 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 San Joaquin County Average
San Joaquin County Average
- ●USDA Zones 9b, averaged across San Joaquin County
- ●One soil character for all of San Joaquin County
- ●Frost dates read at San Joaquin County's scale: Jan 24 to Dec 11
YOUR Parcel
- ✓Your exact zone, not San Joaquin County's 9b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in San Joaquin County
Pull a site-specific report for your exact address in San Joaquin County, California — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that San Joaquin County averages can't show:
We read public map data around San Joaquin County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the San Joaquin County average
How we know this about San Joaquin 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 San Joaquin County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about San Joaquin County
When does frost risk typically end in San Joaquin County?
The last hard freeze (28°F) in San Joaquin County typically lands around Jan 24, 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 14.
How long is the growing season in San Joaquin County?
Measured between 28°F hard freezes, San Joaquin County sees about 321 frost-free days — roughly Jan 24 through Dec 11, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Feb 14 to Nov 27, about 286 days.
Is the soil safe to grow vegetables in San Joaquin County?
The federal record around San Joaquin County runs heavier than most — 5,304 documented sites, mostly Brownfields entries (3,827), the nearest Brownfields record about 0.2 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 San Joaquin County's scale — its 9b band and its 321-day season. Your yard writes its own version of San Joaquin 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 San Joaquin County’s own scale
9 of the readings below were taken at San Joaquin County's own scale — its own ~321-day span between 28°F freezes, the 3 most extensive soil series mapped here and 5,304 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- San Joaquin County's own USDA hardiness band, zones 9bUSDA PHZM 2023
- San Joaquin County's own 28°F hard-freeze dates and its ~321-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in San Joaquin CountyUSDA NRCS SSURGO
- 5,304 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Brownfields record about 0.2 miles outFederal environmental registers
- San Joaquin County's boundary and the 891,072 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9b and a ~321-day seasonGrowable Ground crop-matching engine
- The 2 ecoregions San Joaquin County spans, Central California Valley the largestUS EPA Level III Ecoregions
- Open occurrence records documented in San Joaquin County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto San Joaquin 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 San Joaquin County — the ~321 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 San Joaquin County's 891,072 acreswhy one lot differs from the next →
- Which of those 5,304 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 San Joaquin Countyread your own land →