A Design Professional Summary of Xeric Principles


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Xeriscaping has become a common term utilized to refer to low (or in some cases) no water landscapes. This combination of the Greek word “xeros”, meaning dry, and the common English word landscaping was sprouted right here in Colorado by Denver Water, landscape contractors, and other industry professionals. While some have tried to evolve the word further (read: zeroscape) the intent of xeriscaping is fairly basic and has its roots in responsible and practical landscape implementation. Xeriscape is founded on seven principles which, when properly designed and implemented, can result in significant reductions in cost, maintenance, and resources while often exceeding the seasonal aesthetics of non-xeric landscapes. Xeriscape has become extremely popular and has rocketed past the status of buzzword. It has proven success and is supported by local and regional efforts, native plant enthusiasts, countless nurseries, and well-known horticultural programs and business such as the Denver Plant Select program and High Country Gardens. The benefits of xeriscape have taken root and its popularity has come to fruition due mainly to its simplicity and practicality in regional dry climates. Xeriscape is not a default to vast expanses of rock, devoid of plant coverage. Instead, it emphasizes the following seven principles in an effort to conserve resources while providing unique and aesthetically pleasing landscapes. While each of these principles will be covered in subsequent postings, the list below provides an overview of how these principles create the foundation for xeric landscape implementation.

Planning and design

Planning and design is basically the taproot of a great xeric landscape. This stage can make or break a xeric project. This is where everything begins to take shape, and vital information such as sun exposure, existing soil types, existing structures and landscape elements, slopes, prevailing winds, and other site information is gathered. The design should essentially be a master plan for the entire project. While it may take years to fully implement, the design will provide cohesiveness and govern the proper implementation of the remaining six principles.

Soil improvements

Soil improvements are imperative to a sustainable landscape. Properly prepared soil allows for water infiltration, provides essential nutrients, allows for healthy root development, and provides the elements necessary for biodiversity of bacteria, fungi, and macro and microorganisms. Proper testing and recommended amendments of the soil will ensure long-term success. Generally, soil will require an organic amendment, such as plant-based compost, incorporated into the soil to a depth of 6”-12”, but can often require structural amendments for proper drainage that xeric plants prefer. However, it is critical to obtain a soil PH, structure, and nutrient test to properly determine the soil amendment needs. Soil types will also dictate plant selection, and will greatly influence irrigation applications.

Efficient irrigation

Irrigation is extremely scientific. It goes well beyond avoiding the lack of turgidity (wilting) in plants and simply watering to relieve or prevent the symptoms. Over-watering can be just as detrimental as under-watering. Xeric plants require good drainage and infrequent deep watering for long-term health. There are numerous smart irrigation components to help in water conservation efforts, and true water conservation only occurs when plant selection is coupled with efficient irrigation practices. Several studies demonstrate that landscapes are overwatered from 50 to as much as 400%! Good irrigation practice starts with the creation of hydrozones (zoning of plants with similar water needs) during the design and planning stage, and these will be implemented during the plant selection stage of the process.

Plant Selection

Probably the most exciting part for most, plant selection will be determined during the planning and design and soil amendment steps. Plants must be selected based on sun exposure, soil structure and nutrient profile, and other site observations in order to thrive. Programs such as Plant Select have made native and low water plants readily available. The use of natives in the landscape is a sure step in the right direction. However, plants must be well-suited for their long term growing conditions, or sustainability is compromised through the removal and replacement of materials.

Mulch

When mulch is mentioned, people tend to default to the thought of bark or some other type of wood placed within planting beds. In actuality, mulch refers to organic and non-organic material placed over the finished soil grade. Both organic and inorganic mulches have their benefits, and both serve to retain soil moisture, reduce weeds, and protect roots. Organic mulch is best in long-term drip irrigation situations, and over time will improve soil through decomposition. However, organic mulch tends to repel water in areas where rainwater use for irrigation is desired, and needs to be replaced periodically. This can be offset by the use of plants to provide full coverage in landscape beds. Inorganic mulch fails to provide soil nutrients over time, but allows for infiltration of water in extreme xeric situations. Regardless of type, mulch is imperative to long-term plant health and should be applied at an average 3” depth in all planting beds.

Practical turf areas/turf alternatives

Xeriscape does not preclude turf use. It does, however, limit the use of this high-water treatment to areas of high use, such as recreational activities. Turf has become a seemingly low-budget installation medium, but that low initial cost is easily offset in subsequent years due to the high water demands, frequent fertilizing, aerating, mowing, etc. Reducing turf equates to a drastic long-term reduction in resources, including time spent on maintenance.

Maintenance

The end game of xeriscaping is a reduction in resources, which includes time and money spent on the maintenance of the landscape. Xeriscape provides drastic long-term reductions in required maintenance when properly implemented. As plants mature less water is needed, and the reduction or elimination of turf areas equates to reductions in mowing, fertilizer and pesticide applications, and other practices such as aeration. A healthy xeriscape will need little maintenance, while providing unrivaled aesthetics and long-term sustainability.

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