Trinity County, in Texas, sits in USDA hardiness zone 9a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
Growers here do well with artichoke, fig, california poppy, and cabbage — with the usual caveat that any single yard's soil, sun, and drainage cast the deciding vote.
Trinity County lies within the Piney Woods — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Trinity County holds more than one microclimate.
Soils and elevations shift across Trinity 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 Trinity County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Trinity County — the short answer
Trinity County, Texas: USDA zone 9a, about 289 days between hard freezes, across 444K acres.
- USDA zone
- 9a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Feb 16
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Dec 2
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~289
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 444K 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 9a is Trinity County's average, not your lot's — a low corner or a tree line moves it. Against Trinity County's 289-day season, see what your own ground reads.
Heat and winter chill in Trinity County
Across a year, Trinity County accumulates about 6,268 growing degree days above 50°F, about 444 more than the middle Texas county — ahead of 173 of Texas’s 254 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 703 hours below 45°F, 392 fewer than the Texas middle of 1,095. 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 Trinity County
Across Trinity County, the ground is predominantly Alfisols, where Fuller, Kurth, and Keltys are the most extensive named soil series. The soil is generally moderately well drained with a fine sandy loam surface. Topsoil pH runs about 5.3–5.8, strongly acidic. Rainfall drains through hydrologic group D soils.
Soil order
Alfisols
Drainage
Moderately well drained
Prime farmland
35%
Hydric soils
6%
Soil still varies lot by lot — soil types explained.
How the ground varies across Trinity County
The USDA soil survey maps 53% of Trinity County as moderately well drained — but another 44% drains differently: 34% somewhat poorly drained, 9% well drained.
Fuller is the most extensive named soil at 25% of mapped acres, then Kurth (11%) and Keltys (10%).
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 Trinity County
Each reading below is measured for Trinity 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 Trinity County are moderately well drained, in hydrologic group D — roughly the middle of the drainage range.
This is close to the middle most vegetables prefer: it holds enough water to carry a crop between rains without staying waterlogged. The catch is that a wet spring or a low corner can still tip it soggy.
Plant on the site as-is for most crops, but keep the lowest, slowest-draining beds for moisture-tolerant plantings.
USDA NRCS SSURGO
Surface pH
MeasuredTopsoil across Trinity County runs about pH 5.3–5.8, on the acidic side.
Blueberries, potatoes, and rhododendrons thrive in it, but most vegetables start locking out nutrients below about pH 6.0 and grow pale and stunted no matter how much you feed them.
A measured lime application raises pH for the crops that need it — but test first, because the right rate depends on your own soil, not the county average.
USDA NRCS SSURGO
Season length
MeasuredTrinity County runs about 289 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
Winter hardiness
MeasuredTrinity County sits in USDA hardiness zone 9a.
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 Trinity County is in
Trinity County sits in the South Central Plains — EPA Level III, inside the wider Eastern Temperate Forests. One consistent ecological setting across the whole county.
What Grows in Trinity County
We scored all 1,086 plants against Trinity County's own USDA zone 9a and its own 289-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 Texas profile.
Is it too late to plant in Trinity 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 Jan 19; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Feb 16 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 2 — long-season crops need about 90 days of runway, quick greens only 30. And with a calendar this mild, the honest answer is that planting barely stops — winter opens seasons colder regions never see.
Documented around Trinity County
- monarch butterfly1 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Trinity County
USGS estimates 5,135 lb of Glyphosate on Trinity County farmland in 2019, its largest by weight, ahead of 2,4-d (3,074 lb) and Atrazine (2,818 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 Trinity County — and how to grow with it.
We checked the federal record across Trinity County — 85 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.
The federal record across Trinity County is a modest one — a typical footprint for a growing area. Nothing here calls for alarm; it's worth knowing which recorded sites sit closest to where you grow, and each one on the map carries its type and location. If one turns out to be a near neighbor, a one-time soil test settles the question.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Trinity County
Closest first, across Trinity County. Listing isn't leaking, and distance isn't exposure.
- GROVETON ISDUnderground Storage Tanks · 1.2 mi
- MANGUM WAREHOUSEUnderground Storage Tanks · 1.2 mi
- MANGUM GULFUnderground Storage Tanks · 1.2 mi
- TINAS GULF SERVUnderground Storage Tanks · 1.2 mi
- LLOYD JAMESUnderground Storage Tanks · 1.2 mi
- TRINITY COUNTY SHERIFFS DEPTUnderground Storage Tanks · 1.2 mi
- FRIDAYS TEXACOUnderground Storage Tanks · 1.2 mi
- RINGO GROCERYUnderground Storage Tanks · 1.2 mi
- MANGHAM TEXACOUnderground Storage Tanks · 1.2 mi
- TEX FOR SERV-EMERG POWER TANKUnderground Storage Tanks · 1.2 mi
- NICKS TRUCK & AUTO REPAIRUnderground Storage Tanks · 1.2 mi
- THOMAS WILEY DUBOSEUnderground Storage Tanks · 1.2 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Trinity 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 Trinity County.
Total Sites
85
across Trinity County
Risk Level
Moderate
Highest-severity
1 Toxics Release Inventory facility
Sources Checked
across Trinity County
Severity Distribution
across Trinity County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Trinity County, Underground Storage Tanks runs higher than the national average — 76 sites across Trinity County. Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
Underground Storage Tanks: Underground storage tanks are the single most common source of soil contamination near homes and gardens.
Use raised beds with imported soil — this eliminates the primary soil-contact pathway.
Check your specific parcel in Trinity 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 Trinity County average
Your land is one point inside Trinity County
Everything above resolves to Trinity County as a whole — one PHZM band and one county frost record, read across 444K 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 Trinity County Average
Trinity County Average
- ●USDA Zones 9a, averaged across Trinity County
- ●One soil character for all of Trinity County
- ●Frost dates read at Trinity County's scale: Feb 16 to Dec 2
YOUR Parcel
- ✓Your exact zone, not Trinity County's 9a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Trinity County
Pull a site-specific report for your exact address in Trinity County, Texas — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Trinity County averages can't show:
We read public map data around Trinity County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Trinity County average
How we know this about Trinity 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 Trinity County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Trinity County
When does frost risk typically end in Trinity County?
The last hard freeze (28°F) in Trinity County typically lands around Feb 16, 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 Mar 9.
How long is the growing season in Trinity County?
Measured between 28°F hard freezes, Trinity County sees about 289 frost-free days — roughly Feb 16 through Dec 2, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Mar 9 to Nov 18, about 254 days.
Is the soil safe to grow vegetables in Trinity County?
The federal record around Trinity County shows 85 documented sites, mostly Underground Storage Tanks entries (76), the nearest Underground Storage Tanks record about 1.2 miles out — a typical footprint for a growing area, and proximity to a documented site is information, not a diagnosis of any one yard. It's worth seeing which recorded sites sit closest to where you grow, and testing the soil before new food beds near any of them.
Everything above is measured at Trinity County's scale — its 9a band and its 289-day season. Your yard writes its own version of Trinity 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 Texas's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Trinity County’s own scale
9 of the readings below were taken at Trinity County's own scale — its own ~289-day span between 28°F freezes, the 3 most extensive soil series mapped here and 85 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Trinity County's own USDA hardiness band, zones 9aUSDA PHZM 2023
- Trinity County's own 28°F hard-freeze dates and its ~289-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Trinity CountyUSDA NRCS SSURGO
- 85 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Underground Storage Tanks record about 1.2 miles outFederal environmental registers
- Trinity County's boundary and the 444,068 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9a and a ~289-day seasonGrowable Ground crop-matching engine
- Trinity County sitting wholly inside the South Central PlainsUS EPA Level III Ecoregions
- Open occurrence records documented in Trinity County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Trinity County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every Texas grower plans around — written at state scale, so they stay on the state guidefrom Texas
What this page can’t tell you
- How the season shifts across Trinity County — the ~289 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 Trinity County's 444,068 acreswhy one lot differs from the next →
- Which of those 85 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 Trinity Countyread your own land →