Dallam County, in Texas, sits in USDA hardiness zone 6b — a zone band wide enough that plant choice, not possibility, is the interesting question.
The conditions favor cabbage, hazelnut, lavender, and collard greens, among others — though every individual site edits that list with its own soil, sun, and drainage.
Dallam County lies within the Texas High Plains / Panhandle and the High Plains — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Dallam County holds more than one microclimate.
Soils and elevations shift across Dallam 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 Dallam County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Dallam County — the short answer
Dallam County, Texas: USDA zone 6b, about 197 days between hard freezes, across 962K acres.
- USDA zone
- 6b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 12
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 26
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~197
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 962K 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 6b is Dallam County's average, not your lot's — a low corner or a tree line moves it. Against Dallam County's 197-day season, see what your own ground reads.
Heat in Dallam County
Across a year, Dallam County accumulates about 3,540 growing degree days above 50°F, about 2,284 fewer than the middle Texas county — ahead of 1 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.
Grounded in PRISM Climate Group, Oregon State University — 1991–2020 monthly normals
Soil in Dallam County
Across Dallam County, the ground is predominantly Alfisols, where Dallam, Sunray, and Gruver are the most extensive named soil series. The soil is generally well drained with a loam surface. Topsoil pH runs about 7.2–8.0, slightly alkaline. Rainfall drains through hydrologic group B soils.
Soil order
Alfisols
Drainage
Well drained
Prime farmland
18%
Hydric soils
1%
Soil still varies lot by lot — soil types explained.
How the ground varies across Dallam County
The USDA soil survey maps 99% of Dallam County as well drained — but another 1% drains differently: 1% excessively drained.
Dallam is the most extensive named soil at 35% of mapped acres, then Sunray (10%) and Gruver (9%).
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 Dallam County
Each reading below is measured for Dallam 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 Dallam County are well drained, in hydrologic group B — 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 Dallam County runs about pH 7.2–8.0, on the alkaline side.
Many vegetables cope, but acid-lovers like blueberries struggle, and iron and manganese lock up above about pH 7.5 — leaves yellow between the veins even in rich soil.
Elemental sulfur and generous organic matter lower pH slowly for the beds that need it; test first so you add only what the soil actually calls for.
USDA NRCS SSURGO
Season length
MeasuredDallam County runs about 197 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
MeasuredDallam County sits in USDA hardiness zone 6b.
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 Dallam County is in
Dallam County sits in the High Plains — EPA Level III, inside the wider Great Plains. One consistent ecological setting across the whole county.
What Grows in Dallam County
We scored all 1,086 plants against Dallam County's own USDA zone 6b and its own 197-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 Dallam County?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Mar 15; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 12 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 26 — long-season crops need about 90 days of runway, quick greens only 30. Late in the year the fall bench takes over — quick greens, radishes, and garlic that repays you next summer.
Documented around Dallam County
- monarch butterfly3 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Dallam County
USGS estimates 192,562 lb of Glyphosate on Dallam County farmland in 2019, its largest by weight, ahead of Atrazine (100,226 lb) and Metolachlor & Metolachlor-s (63,248 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 Dallam County — and how to grow with it.
We checked the federal record across Dallam County — 123 documented sites across 6 of the 9 source types we track.
The most significant on record: 5 Toxics Release Inventory facilities. Active industrial facilities reporting chemical releases to air, water, and land.
The federal record across Dallam 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 Dallam County
Closest first, across Dallam County. Listing isn't leaking, and distance isn't exposure.
- THOMPSON EXXONUnderground Storage Tanks · 0.7 mi
- DALHART UNITED SUPPLYUnderground Storage Tanks · 0.7 mi
- DALHART WAREHOUSE 190300Underground Storage Tanks · 0.7 mi
- DALHART FED SAVINGS & LOANUnderground Storage Tanks · 0.7 mi
- PANHANDLE MACHINE SHOPUnderground Storage Tanks · 0.7 mi
- DALHART SHELL EXPRESSUnderground Storage Tanks · 0.7 mi
- COLDWATER N GAS CARD 190302Underground Storage Tanks · 0.7 mi
- AUNT DOROTHYS ATTICUnderground Storage Tanks · 0.7 mi
- AT&T COMMUNICATIONSUnderground Storage Tanks · 0.7 mi
- TONYS LIQUOR STOREUnderground Storage Tanks · 0.7 mi
- ONDRACEK FLORENCEUnderground Storage Tanks · 0.7 mi
- JOHNNYS EXPRESSUnderground Storage Tanks · 0.7 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Dallam 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 Dallam County.
Total Sites
123
across Dallam County
Risk Level
Moderate
Highest-severity
5 Toxics Release Inventory facilities
Sources Checked
across Dallam County
Severity Distribution
across Dallam County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Dallam County, CAFO runs higher than the national average — 23 sites across Dallam County. It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
CAFO: CAFOs pose a different contamination profile than chemical sources.
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Check your specific parcel in Dallam 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 Dallam County average
Your land is one point inside Dallam County
Everything above resolves to Dallam County as a whole — one PHZM band and one county frost record, read across 962K 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 Dallam County Average
Dallam County Average
- ●USDA Zones 6b, averaged across Dallam County
- ●One soil character for all of Dallam County
- ●Frost dates read at Dallam County's scale: Apr 12 to Oct 26
YOUR Parcel
- ✓Your exact zone, not Dallam County's 6b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Dallam County
Pull a site-specific report for your exact address in Dallam County, Texas — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Dallam County averages can't show:
We read public map data around Dallam County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Dallam County average
How we know this about Dallam 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 Dallam County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Dallam County
When does frost risk typically end in Dallam County?
The last hard freeze (28°F) in Dallam County typically lands around Apr 12, 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 3.
How long is the growing season in Dallam County?
Measured between 28°F hard freezes, Dallam County sees about 197 frost-free days — roughly Apr 12 through Oct 26, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 3 to Oct 12, about 162 days.
Is the soil safe to grow vegetables in Dallam County?
The federal record around Dallam County shows 123 documented sites, mostly Underground Storage Tanks entries (72), the nearest Underground Storage Tanks record about 0.7 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 Dallam County's scale — its 6b band and its 197-day season. Your yard writes its own version of Dallam 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 Dallam County’s own scale
9 of the readings below were taken at Dallam County's own scale — its own ~197-day span between 28°F freezes, the 3 most extensive soil series mapped here and 123 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Dallam County's own USDA hardiness band, zones 6bUSDA PHZM 2023
- Dallam County's own 28°F hard-freeze dates and its ~197-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Dallam CountyUSDA NRCS SSURGO
- 123 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Underground Storage Tanks record about 0.7 miles outFederal environmental registers
- Dallam County's boundary and the 962,145 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6b and a ~197-day seasonGrowable Ground crop-matching engine
- Dallam County sitting wholly inside the High PlainsUS EPA Level III Ecoregions
- Open occurrence records documented in Dallam County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Dallam 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 Dallam County — the ~197 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 Dallam County's 962,145 acreswhy one lot differs from the next →
- Which of those 123 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 Dallam Countyread your own land →