One of the most important specialties offered by Exterior Worlds is the creation of unique irrigation systems that maintain the aesthetic and functionality of the Houston landscape from behind the scenes. By definition, a unique irrigation system is a system that is designed in such a manner that it maximizes control of the landscape. It breaks up areas of the yard into smaller pieces, known as zones, and allows the homeowner to control the amount of water specific plant materials receive.
One might assume that a climate as wet as we see here in the Houston landscape would not need irrigation systems at all. Such a point of view is far from the truth. Natural rain water does not fall in a predictable cycle. This is because the driving forces behind the weather patterns of the Houston landscape are warm southerly winds blowing in from the Gulf of Mexico and sporadic blasts of cold air coming down the Great Plains from the Canadian Arctic.
The air from the Gulf is heavily saturated in moisture content, which is why the place feels so muggy and humid all of the time. Cold air from the North is drier and denser. When the two air masses collide, there is an inevitable flurry of rain, driving wind, spikes in humidity, and extremes of temperature that are magnified by that humidity. With such variables, we can never say for certain just how much rain the Houston landscape is going to receive on any given day of the week, how long that rain will last, or when it will or will not rain again.
We as Houston landscaping professionals must therefore take a more aggressive and proactive stance toward subsidizing the natural flow of water to plants. Both the amount of water that goes to plants and the timing of its delivery are vital to the success of any tree, shrub, flower, grass, or special ground cover species.
The exceptions to this rule are naturally drought resistant species which require other strategies of management which are beyond the scope of this article.
In the meantime, it is necessary to understand just how unique some of these irrigation systems are and how much of a vital role they play in maintaining the aesthetic and vitality of the various zones into which the Houston landscape is divided in any given landscape master plan. Specific areas of the yard need controlled and systematic delivery of water to grow and continue to flourish.
The more important among these areas include lawn areas that lie just beneath flower bed areas. Irrigating these areas eliminates competition for water between grass and garden species. Lawn areas that lie in the shade also require additional irrigation. Not only do the trees they surround consume a great deal of water, but the lessened amount of sunlight they receive needs to be offset by an increased volume of water.
Another part of a Houston landscape that always needs a bit of extra attention is any sloped or graded area that breaks away from the otherwise flat terrain that characterizes our geography. Some of these sloped areas are found in yards near bayous such as the ones that run through the Memorial Villages and River Oaks properties near Memorial Park. Others are artificially created by landscape designers so as to create variety and special points of interest in front yard and back yard landscapes.
One of the more ingenious qualities of our irrigation systems is the way we conceal them from open view. The typical system lies underground. It is constructed from pipe, spray heads, a rain sensor, a pressure vacuum breaker (PVB). This last piece is very important, because it is required by city code to prevent contaminated water from comingling with drinking water.
The controls for the irrigation system are located in a box that contains a timer and mounted in an obscure but accessible portion of the yard where service personnel can work on them when necessary. The control box also has a manual control option for those times when the Houston landscape needs the direct, personal touch of the homeowners themselves or landscape maintenance professionals.