From the perspective of the professional landscaper, the constitution of the soil in the Houston landscape is very unique. It is composed almost entirely of clay. As a result of this very atypical composition, Houston soil presents the professional landscaper with some very unique opportunities and unique challenges for lawn and garden designs.
In some respects, it makes the landscape developer’s job easier; in other ways, it makes the landscaper’s job that much more difficult.
In terms of making the professional landscape designer’s work easier, the soil here works to our advantage in one major respect—the absence of large chunks of rock that would otherwise have to be removed or broken up. In other parts of the country, in fact, such as Austin, landscape architects routinely have to cut through rock to install irrigation pipes or even plant a basic garden.
However, in a world of polarities, each advantage carries with it an equivalent disadvantage. When it comes to working with the clay soil of the Houston landscape, we landscape designers face an entirely different set of challenges than do our counterparts on the East Coast, the Great Plains, and the American West.
Simply put, Houston is just not that great of a place to plant a garden without professional assistance and specific expertise in botany available only through firms with trained landscaping professionals.
This is because clay is far too compact for plant roots to easily spread through the soil. This makes it difficult for them to grow. Our soil also traps water rather than draining it, which in turn will cause many plants to drown.
In Houston, we always have to break up the clay dirt in yards and till into it special fertilizer and soil mixtures.
Such a challenge is not at all difficult for an experienced Houston landscape design firm such as Exterior Worlds. The problem here lies more in the do-it-yourself realm. Houston’s frequent rains and warm climate offer a deceptively appealing invitation to “plant your own garden” in what appears to be an ideal environment for plants to grow. Many people try this all over the city.
Unfortunately, they commonly fail to till the soil sufficiently, and even when they do, often find it difficult to choose the appropriate fertilizer amounts necessary to optimize the soil for planting. What begins as a beautiful gardening soon withers and dies, requiring the homeowner to finally contact a professional garden designer who can install a new design that will withstand the elements and contribute lasting beauty to the Houston landscape.
People also face similar challenges when attempting to plant nonindigenous tree species. Trees face the same challenges that other plants in relationship to clay dirt that blocks adequate root system growth. While this seldom kills a tree, it often causes it to grow in dwarfed proportions to what it normally would in its native environment.
There are times, though, when such a downsizing of tree growth can work to our advantage. If we are looking to soften the view of the surrounding Houston landscape in a crowded neighborhood or if we are trying to make a small yard look large, small trees can create a sense of organic boundary and help enlarge the corresponding open spaces of an otherwise diminutive yard.
Otherwise, if we want non-native species to grow to normal heights, we have to alter the soil content of the Houston landscape. This can be very costly to the homeowner, who is already investing a significant amount of money in landscape design.
It is therefore more practical to landscape front yards and back yards with native tree species that have evolved adaptive countermeasures to thick, stubborn soil and that can handle excessive amounts of rain water that intermittently fall over the Houston landscape.
The impact of Houston soil on outdoor architecture is somewhat mixed. Clay itself shifts too much to be stable near the surface of the earth. Cay is expansive, so it absorbs water and expands in a way that can raise or lower a structure. This especially impacts pool stability.
However, the deeper you go underground, the more stable the clay becomes. “Stabilized” clay is an ideal support for footing and piers which are needed to build almost all outdoor buildings. Such footing and piers can be built underneath a pool shell and create remarkable stability for a luxury swimming pool or natural swimming pool of any size.