BUILD · PLANTING
Planting.
Planting at Alterra reads from the ecoregion outward — native where the site supports it, adapted where the design calls for more, and a working palette shaped by what actually survives in DFW clay and DFW winters.
Native where we can, adapted where the design calls for it.
A native species in DFW carries tens of thousands of years of adaptation to local conditions — alkaline pH, shrink-swell clay, a rainfall pattern that swings from drought to eight inches in a week, a temperature envelope that now includes Uri-scale events. An adapted species is a non-native that tolerates these conditions with specific management. The two categories do different work. Native-first means lower establishment risk, longer performance over a decade-long horizon, and reduced irrigation dependency once the plant has rooted in. Adapted-as-accent means more design flexibility in specific moments where the native palette does not yet offer the exact register the composition wants. We lead with native; we reach for adapted only where the specific design need cannot be met otherwise, and we specify adapted choices with the same discipline we apply to native ones.
The Blackland Prairie runs east of the Trinity River through Collin County and into Hunt County beyond — calcareous clay on a tallgrass substrate where post oak and cedar elm hold the upland canopy, live oak holds the creek bottoms, and sideoats grama, little bluestem, and the native forb community carry the understory. West of the Trinity the Eastern Cross Timbers takes over — sandy loam over sandstone, where post oak is still the canopy namesake but the understory palette shifts. A planting plan that serves a Lakewood client will quietly fail in Westover Hills, and the other way around. We read the ecoregion at the Site & Story walkthrough and let it shape the working palette before the drawings close. See Blackland Prairie and Cross Timbers for the deeper frame, and native palettes for the working species list. The coordinated drawing set behind each install is authored in landscape design.
SOIL
What grows in alkaline clay.
Typical DFW soil tests run at pH 7.8 to 8.2 — squarely alkaline — with calcium-carbonate inclusions that drive iron lockout on acid-loving species even when iron is present. The clay itself is the Houston Black or Austin silty clay of the Blackland Prairie, a soil that cracks open in August to inches-wide fissures and tightens shut around a root ball in November. It is not a failure mode of a forest soil; it is its own ecological substrate, with its own assembled community of natives. Designing inside it rather than against it narrows the palette to what the prairie and the Cross Timbers transition were already growing, and widens the specification into what the soil actually wants: calcium-loving species, deep-rooting perennials, grasses and forbs that handle the shrink-swell cycle without splitting.
Off our working lists: Japanese maples in full sun (acid-loving, iron-deficient in alkaline clay), azaleas outside pre-amended beds (which amount to imported-soil raised beds, maintenance-heavy and marginally justified), and eastern redbud cultivars bred for acid soils that fail to establish through a second summer in Blackland pH. In their place, the Blackland itself offers: cedar elm (Ulmus crassifolia) as an under-canopy specimen where the scale wants a subtler silhouette than live oak; desert willow (Chilopsis linearis) as a drought-tolerant flowering tree on drier exposures; Texas mountain laurel (Sophora secundiflora) as an evergreen flowering specimen where the register calls for a more architectural form; and Mexican redbud (Cercis canadensis var. mexicana), a variety adapted to alkaline substrates, where the redbud register is desired.
The first year after planting.
Post-planting, the default watering specification is deep and infrequent rather than frequent and shallow: a long, slow soak at the root ball twice a week during establishment, cadence adjusted for soil type and season. Blackland clay holds water longer than sandy loam and asks for less frequent application — over-watering in clay drives the same root-rot failures in newly planted material that under-watering drives in Cross Timbers soils. The critical window is the stretch from final planting through the first summer. For fall-installed material — September through November, our primary install season — the first full stress event is the following July. For spring-installed material, it is the July of the same year. We coach the homeowner on what to read at the surface and how to adjust before the plant tells us something is wrong.
Mulch depth runs 3 to 4 inches, pulled away from the root crown so the trunk reads dry. A ring around a freshly planted tree is held at 18 to 24 inches of clearance — enough for the crown to breathe, not so much that the ring reads decorative. Staking is the minimum required for the specimen and the exposure: for most installs, 12 to 18 months, with tie material soft enough that it will not girdle the trunk and removed on a calendared date rather than left in place. At handoff we hand the homeowner a written care calendar alongside the one-year plant-performance review. The warranty builds in the 1-year review; it is not an add-on. A plant that goes into stress in the second July is a data point we want to see.
RESILIENCE · PLANTING AFTER URI
Freeze-mortality as planning default, not surprise.
Warm-season ornamental grasses marketed as cold-tolerant that proved to be conditional — certain Muhlenbergia cultivars at immature caliper, certain Pennisetum selections that had drifted onto zone-8 tags without a freeze record — came off our installed-new spec list. Agaves sold under the “cold-hardy” register that bloomed and died or root-rotted after the sustained freeze: off the list, except in specific microclimates. Sub-tropical screening shrubs — Japanese pittosporum and the tender Ligustrum cultivars — were removed entirely. The February 2021 event drove air temperature into the single digits for hours across multiple days. Zone 8 cold tolerance as measured against a normal 3-to-5-hour freeze is insufficient against a 72-hour sustained event. Our working palette is the narrower set of species with a documented record on the other side of Uri.
Escarpment live oak (Quercus fusiformis) has moved to default on drier western sites where southern live oak (Q. virginiana) had been the casual choice; both hold, but fusiformis performs better in sustained cold. For understory and mid-story: Texas mountain laurel (Sophora secundiflora) where the evergreen flowering register is wanted and Mexican redbud (Cercis canadensis var. mexicana) where a spring flowering tree is needed. For evergreen screening: yaupon holly (Ilex vomitoria), a native that has performed through every DFW freeze on record. For grasses: sideoats grama (Bouteloua curtipendula), little bluestem (Schizachyrium scoparium), and prairie dropseed (Sporobolus heterolepis), all of which go dormant on cue and return. Cultivar-level specificity matters: we name the cultivar, not just the species, on the plan.
In the 72 hours after the first hard freeze of the season, we walk every project site where the planting is less than three years old. We document which species went dormant on cue, which showed partial canopy loss, which showed bark split, and which failed. Dieback is not mortality in January — many native species will look dead in February and leaf out cleanly in April — so we defer the mortality call until May or June, when the leaf-out window has closed. The observations feed back into the Site & Story phase of every subsequent project on comparable soils and exposures, and they also inform the homeowner's written care calendar for the coming spring. See the full resilience practice for how this feeds the build spec forward.
WORKING PALETTE
A short list that survives here.
- Live oak — Quercus fusiformis (escarpment live oak, drier western DFW sites); Quercus virginiana (southern live oak, moister eastern sites). Hybrid zone extends through much of the metro.
- Post oak — Quercus stellata. The Cross Timbers namesake.
- Eastern red cedar — Juniperus virginiana. DFW-native juniper. Not to be confused with Ashe juniper (Juniperus ashei), which is Hill Country and Edwards Plateau, not DFW.
- Sideoats grama — Bouteloua curtipendula. The Texas state grass.
- Little bluestem — Schizachyrium scoparium. Fall color in the Blackland Prairie meadow context.
- Prairie dropseed — Sporobolus heterolepis. Fine texture, reliable in adapted DFW exposures.
- Yaupon holly — Ilex vomitoria. Native evergreen screen or small specimen, tolerant of clay and drought, has performed through every DFW freeze on record.
- Cedar elm — Ulmus crassifolia. Native canopy-scale tree where live oak reads too heavy; amber-yellow fall color in the Blackland Prairie context.
- Flameleaf sumac — Rhus lanceolata. Small specimen or large multi-stem, native fall color, poolside-viable at mid-distance.
- Texas mountain laurel — Sophora secundiflora. Evergreen flowering specimen for more architectural compositions; through-Uri record good.
- Mexican redbud — Cercis canadensis var. mexicana. Alkaline-adapted redbud variety; performs where eastern-redbud cultivars fail on Blackland pH.
- Lindheimer's muhly — Muhlenbergia lindheimeri. Fine-textured native ornamental grass, evergreen clumping in most winters, the freeze-tolerant default where muhly register is wanted.
- Autumn sage — Salvia greggii. Native shrub, drought-tolerant, long bloom window from May into first frost; honest poolside choice.
- Inland sea oats — Chasmanthium latifolium. Shade-tolerant native grass for understory plantings beneath live oak canopy.
This is a working list rather than an exhaustive one. We update it against each project's one-year and three-year plant-performance review, and against the continued record on the other side of Uri. A palette that does not change is a palette that has stopped paying attention.
SELECTED PLANTING WORK
[OPERATOR: add projects with naturalistic, xeriscape, or cottage typology to display featured planting work here.]