Until recently, water conservation was strictly an issue facing the dry western states. But as our population grows, the existing water supply may not keep pace with increasing demands elsewhere. Whether this is related to drought or inadequate delivery infrastructure, it is now a more widespread challenge. With efforts to live green with greater sensitivity to water consumption, dry landscaping strategies are in demand everywhere.
The term xeriscape describes a landscape that demands little water. It is composed of naturally drought resistant species from North America and dry climates around the world. In the dry western states, this style of landscape also supports exotics from South Africa, the Middle East and Australia. These plants are naturally adapted to the same long dry season as most western natives making them compatible in the garden. Because of water concerns, many western homeowners are turning to lawn-free landscapes.
In the east xeriscape is more challenging because it is too cold and moist for these dry climate species to survive there. Regular summer rainfall also precludes most Mediterranean species that compose the large percentage of the western plant palette. The strategy here is to utilize native plants that are already perfectly adapted to thrive on local rainfall. Once established, these ask for no extra water in summer or much care in winter because they have evolved to adapt locally. Other American natives plus a few exotic species from other cold humid regions of the world may do equally well here.
In terms of planting design, it is important to determine just how dry a landscape will be. This dictates how to combine plants with similar water demands. However, a nursery grown plant will not take on the drought resistance of its wild counterpart for at least two years or more. Many plants that are very drought resistant in habitat can have a hard time adapting to conditions in the nursery. Their root system cannot spread out as it should due to constraints of the container. Therefore these will require significant irrigation the first and possibly the second dry season to help roots travel deep enough to support the plant without irrigation. As it becomes more established, the irrigation is cut back or phased out entirely. This illustrates why early maintenance of a newly installed xeriscape is paramount to its success.
- Pro Tip: In the West, fall is the best time to install a xeriscape while plants are dormant. This allows all winter and spring to become established before summer heat and drought arrives.
In the west, irrigation is essential. The underlying principal in the xeriscape is low pressure systems. These are designed to deliver water to the root zone and nowhere else. The original drip irrigation invented in Israel delivers a small amount of water to a single location where it can penetrate deep into the soil. This depth is vital to luring roots downwards, venturing deep to harvest the moisture there when the surface soil is dry. This trains plants to root beyond their original pot-shaped root ball. After awhile the deep roots will be able to sustain the plant even if the drip system is phased out.
But more often the drip system remains in place and is used to ensure the plant is sufficiently hydrated not just to survive, but to look good and bloom abundantly in your landscape. This is vital to those species which choose the driest time of year to become dormant, which is summer and fall in the West. Some become deciduous when summer dormant, while others partly so. With irrigation the deciduous species may retain enough foliage to remain attractive during these seasons.
All this deep rooting is found in most western natives, particularly those from California. Study these species in habitat and they are often found on hillsides, cliff faces, and in sandy gravelly ground along dry washes. They have evolved to root very deeply to reach moisture during the dry season. If planted in heavy clay, this rooting may be stunted and the soil may not be able to absorb enough water to support plants. Therefore the plant may fail to reach its optimal level of drought resistance, and it may not prove sufficiently long lived either. This is why soil conditions come into play with xeriscapes due to the preferences of the plants adapted to drought.
A mulch is simply an organic or mineral material spread on top of the ground to make conditions more amenable for plants. Mulches help to prevent moisture evaporating from the surface of the soil. They also shade the soil so it doesn’t heat up so much in the summer. It is also vital for preventing weed growth that can compete with landscape plants for limited water.
Mulch availability is different in each region, the cost effective choices originating close by. This limits trucking costs and helps the xeriscape blend into the surrounding style of gardens. For example, the southwest has always relied on naturalistic fine gravels. In the Pacific Northwest forest industry byproducts such as wood chips and ground bark are cost effective. In the south pine needle much is standard.
5. Free Style
Do not assume that all xeriscapes look like a southwestern desert scene. Mediterranean species have long been used in European gardens, and these can lend a formal French style or a rural Tuscan feel while conserving water. Drought resistant plants from Africa and Australia can be chameleons, lending character and color to virtually any theme or style. Your designer knows that conservation is as easy as specifying a drought resistant alternative to a water loving tree or shrub. So long as this alternative is well adapted to the local climate, your xeriscape style is only as limited as your designer’s knowledge of plants.
For anyone contemplating a xeriscape, selecting an experienced designer is vital to success. Not all are keyed into this palette of un-thirsty plants, and may lack direct knowledge of western natives that are finicky about water in the wrong season. The skill set in demand is a firm knowledge of both local native species used for landscaping, plus the array of imported species from dry climates around the world that expand our options considerably. There is no better way to make your home environmentally green and create a model landscape for water conservation.
[source: Landscaping Network]