The Blackland Prairie spans USDA hardiness zones 8a-9a — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
Here the soil, not the zone, defines the garden. The Blackland Prairie is a narrow black-clay belt tracing the I-35 corridor from Sherman through Dallas, Waco, and Temple down to Austin — built on vertisol "black gumbo" that swells sticky when wet, then cracks open as it dries. That shrink-swell clay is alkaline and slow-draining, so where the sandy acid soils of the Piney Woods to the east or the thin limestone of the Hill Country to the west let many gardeners plant straight in the ground, growers here reach for raised beds, gypsum, and heavy organic amendment first. The season runs long — commonly 264 to 300 frost-free days across zones 8a to 9a — but it's the black clay, not the calendar, your beds have to answer to. These conditions suit okra, black-eyed pea, tomato, and jalapeno — a starting list any specific site will trim or extend with its own soil, sun, and drainage.
The Blackland Prairie spans Texas.
Your yard isn't all of the Blackland Prairie.
The Blackland Prairie spans USDA zones 8a-9a, but your parcel sits in exactly one — and slope, tree cover, and low spots nudge it further. 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 Blackland Prairie — soil, climate, flood, and parcel records. How we handle your address.
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The Blackland Prairie — the short answer
The Blackland Prairie: USDA zones 8a-9a, 264–299 frost-free days depending where in it you stand, in Texas.
- USDA zones
- 8a-9a
- USDA PHZM 2023, aggregated over the footprint
- Shortest season here
- 264 days
- NOAA Regional Climate Centers ACIS, 1991-2020 — Fannin County
- Counties
- 16
- US Census TIGER/Line 2025
- Region type
- County cluster
- Growable Ground growing-region registry
Region boundary: Growable Ground growing-region registry — curated county clusters, EPA Level III ecoregions, and town clusters drawn finer than any county. The season figure is this region's own record, measured across its 16 member counties, not a state or national average.
Hardiness Zone Range
The Blackland Prairie is not one growing season
One answer for the Blackland Prairie averages 16 counties whose growing seasons are 35 days apart — from 264 frost-free days in Fannin County to 299 in Travis County. That is the same region, measured the same way, in the same years. Which end of it your land sits nearer decides what finishes before the first hard freeze.
The middle half of 16 counties runs 277–290 days, with a median of 286 days — a 35-day span end to end.
Measured across 16 member counties, each carrying its own 28°F normal. NOAA Regional Climate Centers ACIS, 1991-2020. A member with no own record is absent from the range rather than counted as zero — nothing here is interpolated to the region. Your own site sits somewhere inside this range; a parcel report resolves where.
Where the line runs inside the Blackland Prairie
The middle half of the Blackland Prairie runs 277–290 frost-free days, and 7 of its 16 counties sit outside that — 3 on the short side, 4 on the long. A regional planting date describes the middle well and the ends poorly, which is worth knowing before you follow one.
Under 277 frost-free days
3 counties
- Fannin County · 264 days
- Grayson County · 274 days
- Collin County · 276 days
The end of the region that sets the planting calendar — start seed indoors here and the season stretches to meet the crop.
277–290 frost-free days
9 counties
0 of 9 shown
The middle half of the region, and the part a single regional season describes well.
Over 290 frost-free days
4 counties
- Travis County · 299 days
- Falls County · 294 days
- Dallas County · 294 days
3 of 4 shown
Long enough for a second succession of a quick crop after the first comes out.
Each county is placed by its OWN 28°F frost-free normal (NOAA Regional Climate Centers ACIS, 1991-2020), the same figure its own guide page publishes. Elevation, slope and cold-air drainage move a site within its county as well — which is the part only your address resolves.
What Grows in the Blackland Prairie
All 5 of the plants below that publish a season requirement clear even Fannin County’s 264 frost-free days — so on season alone, this grid works at both ends of the region. The 35-day spread still decides how far past this list you can push, and how early you can start.
Plants matched to the Blackland Prairie's USDA zones 8a-9a, ordered by how much hardiness margin each has across the region — the ones with room to spare at both ends of this band lead. Each links to its full growing profile.
Native Plants of the Blackland Prairie
Plants the USDA PLANTS Database documents as native and present in this region’s state, kept only where the published hardiness range meets the Blackland Prairie’s USDA zones 8a-9a — closest range match first. Presence is recorded by state, so a plant can be documented across the state and still be scarce in your corner of the region.
The ground across the Blackland Prairie
The USDA soil survey maps this ground county by county. These are those records weighted by land area across 16 member counties — this region’s own profile, not a state figure.
The ground is predominantly Vertisols, at 42% of mapped acres, followed by Alfisols (27%), Mollisols (21%) and Inceptisols (6%). Six soil orders appear somewhere inside the footprint, which is the honest reason a regional soil answer only goes so far. The most extensive named soils are Houston Black, Heiden, and Crockett.
50% of those acres are moderately well drained, and another 45% well drained, 1% somewhat poorly drained. Topsoil pH runs 5.8–8.2 between the lowest and the highest county on record. 31% of the footprint is classed prime farmland.
Soil order
Vertisols
Drainage
Moderately well drained
Topsoil pH
5.8–8.2
Hydric soils
3%
Soil changes across a driveway, so which of these your own ground sits on is a parcel question rather than a regional one. Ellis County holds the most wetland ground here, at 9% — soil types explained.
USDA NRCS SSURGO via Soil Data Access
What this means for growing in the Blackland Prairie
The soil survey reads this ground county by county, and the readings above are those records summed across the Blackland Prairie. Here is what they mean for a garden here — and the move an experienced grower makes about each one.
Drainage
From county records50% of the mapped acres across the Blackland Prairie are moderately well drained — roughly the middle of the drainage range. That is area-weighted across all 16 of its mapped counties.
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
From county recordsTopsoil across the Blackland Prairie runs pH 5.8–8.2 — alkaline in nine of its 16 counties.
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
Safe to Grow Here?
What the federal record shows across the Blackland Prairie — and how to grow with it.
Across the Blackland Prairie's 16 counties the federal record holds 15,361 documented sites, mostly Underground Storage Tanks (10,757), Brownfields (2,848) and Toxics Release Inventory (1,173). The heaviest single county is Dallas County, with 6,622.
That is a regional count, not a reading of any one lot — proximity to a documented site is information, not a diagnosis. Open the map outlined to the Blackland Prairie to see which records sit where you actually grow.
Sources Checked
Summed across the 16 counties in the Blackland Prairie
A note from Gnorman
What an experienced grower watches for around here
In and around the Blackland Prairie, two things run higher than the national average across the 16 counties in the Blackland Prairie — PFAS (169 sites) and Toxics Release Inventory (1,173 sites). Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
PFAS: PFAS (per- and polyfluoroalkyl substances) are called "forever chemicals" because they do not biodegrade.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Test irrigation water source — this is the primary pathway for PFAS to reach garden crops.
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
Your land is one point inside the Blackland Prairie
Everything above resolves to the Blackland Prairie as a whole — a footprint whose own counties record seasons 35 days apart, and hardiness across zones 8a-9a. Your parcel sits at one point in that range, not in the middle of it. 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 region 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 regional average.
Your Lot vs the Blackland Prairie Average
Blackland Prairie Average
- ●USDA Zones 8a-9a, averaged across Blackland Prairie
- ●One soil character for all of Blackland Prairie
- ●State-average frost dates
YOUR Parcel
- ✓Your exact zone, not Blackland Prairie's 8a-9a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in the Blackland Prairie
Pull a site-specific report for your exact address in the Blackland Prairie — soil, sun, drainage, frost risk, contamination, and scored plant recommendations.
Three things about your lot that Blackland Prairie averages can't show:
We read public map data around The Blackland Prairie — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Blackland Prairie average
How we know this about the Blackland Prairie
The boundary: a cluster of neighboring counties. Growing regions have no official boundary, so this footprint is our published one, and every figure on this page was measured over the counties inside it rather than borrowed from the state around it.
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, aggregated across the footprint; the growing season from NOAA Regional Climate Centers ACIS 1991–2020 28°F normals, read at each member’s own record; boundaries from US Census TIGER/Line 2025; the contamination record from the federal sources named in that beat above; the soil from the USDA NRCS SSURGO survey, read at each member county’s own record and weighted to this footprint by land area. Where a member carries no record of its own, it is absent from the figure rather than filled in.
Common questions about the Blackland Prairie
What hardiness zone is the Blackland Prairie?
The Blackland Prairie spans USDA hardiness zones 8a-9a, aggregated from the USDA Agricultural Research Service Plant Hardiness Zone Map 2023 across the region's counties. Zones reflect average annual extreme minimum temperatures from 1991–2020 data.
How long is the growing season in the Blackland Prairie?
Measured between 28°F hard freezes, the Blackland Prairie's counties mostly run 277 to 290 frost-free days, median 286 (NOAA Regional Climate Centers ACIS, 1991–2020, over 16 member counties). That 13-day spread is the honest read — no single season describes 16 counties, and each county guide below carries its own.
When does frost risk end in the Blackland Prairie?
Across the Blackland Prairie, the middle half of member counties see their last 28°F hard freeze between Feb 16 and Feb 23 (median Feb 18), and their first fall freeze between Nov 28 and Dec 2. Those are hard freezes, not the last light frost: tender transplants wait for about Mar 11, and elevation decides which end of a 7-day spread you garden in.
What grows well in the Blackland Prairie?
The Blackland Prairie's conditions suit plants such as Okra, Black-eyed Pea, Tomato, Jalapeno, Sweet Potato, Fig. What actually thrives on any one site still turns on its specific soil, sun, and drainage — we score each plant against the real conditions at your address.
How is the Blackland Prairie defined?
The Blackland Prairie is defined here as a curated cluster of 16 neighboring counties that share a growing character. Growing regions have no official boundary, so this footprint is our published one — every county in it is named on this page.
Which states does the Blackland Prairie cover?
The Blackland Prairie spans Texas. Each state's full growing guide is linked on this page.
What other growing regions cover the same states?
High Plains, Piney Woods, Texas High Plains / Panhandle, Gulf Coast, Coastal Bend, and Texas Hill Country share at least one state with the Blackland Prairie. Growing regions overlap and interlock — a single address can sit inside more than one, which is why the precise read is always the parcel, not the region.
What this page reads at the Blackland Prairie’s own scale
6 of the readings below were taken at the Blackland Prairie's own scale — the zone 8a-9a band across its footprint, a median 286-day season across its 16 counties and 15,361 documented federal contamination records across its 16 counties, 6,622 of them in Dallas County alone; one is borrowed from a wider read, named and linked below.
Measured here
- The USDA hardiness band 8a-9a aggregated across all 16 counties in the footprintUSDA PHZM 2023
- The boundary itself — the 16 counties this region is curated fromGrowable Ground subregion registry
- The growing character that makes this region distinct from the states it crossesGrowable Ground subregion registry
- The 28°F season across the footprint — the middle half of its 16 counties run 277 to 290 frost-free days, median 286NOAA Regional Climate Centers ACIS, 1991-2020
- The federal contamination record over the whole footprint — 15,361 documented federal contamination records across its 16 counties, 6,622 of them in Dallas County aloneEPA, USGS and USDA federal site records
- The soil order mix across the footprint — 42% Vertisols, topsoil pH 5.8–8.2, area-weighted across its 16 mapped countiesUSDA NRCS SSURGO
Inherited from a wider read
- The candidate plant list — its state's curated sets, merged and filtered to zones 8a-9afrom Texas
What this page can’t tell you
- Which end of the 13-day range your ground sits at — 277 days at one extreme, 290 at the other, decided mostly by elevationfrost dates explained →
- Which of those soils your own ground sits on — the survey maps them county-wide, and they change across a drivewaysoil types explained →
- The soil pH, drainage, sun hours, and frost pockets on one specific lotwhy one lot differs from the next →
Explore the Blackland Prairie
State growing guides
Counties in this region
Other growing regions across Texas
A semi-arid shortgrass tableland of deep soils and big sky, where wind, low rainfall, and irrigation shape dryland wheat, sorghum, and resilient gardens.
The sandy, acidic pine-and-hardwood forest belt of East Texas and western Louisiana — the humid South Central Plains, where a long frost-free season of roughly nine months favors heat- and acid-tolerant Southern gardens.
The southern, warmer anchor of the High Plains — the Llano Estacado tableland west of the Caprock Escarpment, where a longer season (frost-free days run near 227 across the Texas counties, well above the multi-state High Plains average) and deep-well Ogallala irrigation define the growing reality. This is the largest contiguous cotton patch in the world around Lubbock (Texas Co-op Power), and, west of the Caprock, the Texas High Plains AVA (TTB, 27 CFR 9.144) that grows roughly 80% of the state's wine grapes. High, flat, and semi-arid: what grows here is what deep-well water and a zone 7a-8a season can coax from it, a distinctly Texan story rather than the dryland wheat and sorghum of the northern High Plains.
The humid, near-frost-free coastal rim of the Gulf of Mexico — long seasons, sandy and alluvial soils, heat, and hurricanes shaping what thrives. (Representative coastal counties, not exhaustive.)
The 11 counties of Texas's Coastal Bend, anchored on Corpus Christi and the Nueces estuary, span USDA hardiness zones 9a to 10a with frost-free seasons running 311 to 343 days.
A limestone upland of thin alkaline soils, spring-fed creeks, and live-oak savanna known for peaches, wildflowers, and increasingly vineyards.