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 pecan, tomato, okra, and bluebonnet, among others — though every individual site edits that list with its own soil, sun, and drainage.
Dallam County lies within 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 1,112 plants against your land's actual soil, sun, and frost.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Quick Facts
USDA Zones
6b
Last Hard Freeze (28°F)
Mar 22
County normal — light frosts run a few weeks later
First Hard Freeze (28°F)
Nov 8
County normal — light frosts arrive a few weeks earlier
County Area
962K acres
Hardiness Zone Range
Zone maps are averages across Dallam County. Your yard's slope, trees, and frost pockets shift what actually grows — see your land's exact reading.
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.
What Grows in Dallam County
Plants matched to Dallam County's USDA zones 6b — each links to its full growing 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 Feb 22; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 22 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 8 — long-season crops need about 90 days of runway, quick greens only 30. There is slack in a calendar like this — late plantings, second rounds of favorites, and a fall bench that keeps beds working.

Growing Challenges in Texas
What an experienced grower plans around here — each one has a move.

Extreme heat (100F+ days) stresses many crops from June through September
Run the garden on spring and fall windows and give summer survivors afternoon shade — timing beats fighting the heat.

Rainfall varies dramatically — 8 inches in west TX to 56 inches in east TX
Your county's rainfall, not the state's, sets the watering plan — check your exact spot before designing beds.

Heavy black clay (Blackland Prairie) is difficult to work and drains poorly
A raised bed with amended soil turns Blackland clay from an obstacle into a backdrop — and that clay feeds deep roots well.

Flash drought conditions can develop rapidly even in wet years
Mulch deep and water deeply-but-rarely to grow drought-tough roots; a drip system pays for itself in the first dry summer.
For cultivar selection, pest pressure, and planting-time guidance specific to Texas, the Texas A&M AgriLife Extension Service is the authoritative local source.
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.
Environmental Intelligence
Understanding what's nearby helps you make informed decisions about where and how to grow.
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 nearby. 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 1,112 plant recommendations.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Your Specific Parcel Matters
Dallam County Average
- ●USDA Zones 6b
- ●Generic soil type for the area
- ●State-average frost dates
YOUR Parcel
- ✓Your exact hardiness zone
- ✓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 exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Key Growing Facts for Dallam County, Texas
- USDA Hardiness Zones: 6b (USDA PHZM 2023)
- Last Hard Freeze (28°F): Mar 22 (county normal, NOAA 1991–2020 Climate Normals — light frosts can follow for a few weeks)
- First Hard Freeze (28°F): Nov 8 (county normal, NOAA 1991–2020 Climate Normals — light frosts can arrive a few weeks earlier)
- Days Between Hard Freezes: ~231 (county normal, NOAA 1991–2020 Climate Normals)
- County Land Area: 962K acres (US Census TIGER 2025)
Zone data: USDA ARS Plant Hardiness Zone Map 2023. Climate data: NOAA NCEI. County boundaries: US Census TIGER/Line 2025.
Frost dates here are the Dallam County average. Low spots and tree cover move them by days on any one yard — see your exact frost windows.
Frequently Asked Questions
What hardiness zone is Dallam County, Texas?
Dallam County sits in USDA hardiness zone 6b, per the USDA Plant Hardiness Zone Map 2023. Zones reflect average annual extreme minimum temperatures from 1991–2020 weather data.
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 Feb 22; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 22 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 8 — long-season crops need about 90 days of runway, quick greens only 30. There is slack in a calendar like this — late plantings, second rounds of favorites, and a fall bench that keeps beds working.
When does frost risk typically end in Dallam County?
The last hard freeze (28°F) in Dallam County typically lands around Mar 22, per NOAA 1991–2020 climate normals — an earlier marker than the light-frost dates many planting charts quote. That marks the hard freeze, not the last light frost — light frosts can still bite for a few more weeks, so tender transplants usually wait another 2–3 weeks.
How long is the growing season in Dallam County?
Measured between 28°F hard freezes, Dallam County sees about 231 frost-free days — roughly Mar 22 through Nov 8, per NOAA 1991–2020 climate normals. Tender crops get a somewhat shorter practical window, since lighter frosts reach a few weeks past the hard-freeze dates on both ends.
What vegetables grow in Dallam County?
Dallam County's zone 6b supports a wide range — strong performers include Pecan, Tomato, Okra, Bluebonnet, and Jalapeno. What actually takes on any one site comes down to its soil, sun, and drainage, and we score each plant against the real conditions at your address.
Which hardiness zone is Dallam County, really?
Officially, Dallam County sits in USDA zone 6b (USDA PHZM 2023) — but a zone is a 30-year average of winter's coldest night across an area, and it can't see any one yard. A south-facing slope, a tree line, or a low frost pocket can shift a single site by half a zone either way, which is why neighboring gardeners often quote different numbers. We read the conditions at your exact address — soil, sun, slope, and frost — and score 1,112 plants against what's actually there.
Is the soil safe to grow vegetables in Dallam County?
The federal record around Dallam County shows 123 documented sites — 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.
Just moved to Dallam County — what should I know before planting?
Start with three facts. Dallam County sits in USDA zone 6b, which sets what survives winter; the last 28°F hard freeze typically clears around Mar 22, with about 231 frost-free days to work with (NOAA 1991–2020 climate normals); and 123 documented sites sit on the federal record — a typical footprint for a growing area, worth a look on the contamination map before food beds. From there, matching plants to your actual soil and sun is the fun part.
Everything on this page is a Dallam County average. Your yard writes its own version — 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.
