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Tuesday, January 22, 2013

Considerations for Desert Landscape Designs

            One of the fears about landscapes designed for desert environments is that the design will actually use more water than was anticipated. In the process of using more water than anticipated and lack of attention to design considerations, the energy consumption of the building or home might increase.

Minioasis concept taken from Sunset Magazine many years ago. Hope you guys don't mind.
            Landscape designs are extensions of the home and should provide usable areas that add to our quality of life. Recently a homeowner asked how to know if a landscape designer was a good one or not. A good designer will sit down and ask you what your needs are as a family or a business. A good designer will incorporate as many of these needs as possible into the design.. If the designer doesn’t ask about your needs, get a different designer.

            Concentrate most the plants near the home and decrease plant density away from the home or building. Common terms used to describe this are minioasis and hydrozoning designs. This technique allows you to use high water use plants near the foundation where shading of the windows and walls can occur. In Las Vegas, where we have some gypsiferous soils in parts of the valley, this can present a problem if these “foundation plants” are overwatered. The high sulfates contained in some of our soils may damage concrete patios and foundations. Check with a soil survey map or have the soil analyzed for high sulfates. The only solution to this type of problem is to keep foundation plantings on drip emitters and far enough from concrete so that the water/soil solution can’t react with the concrete. Most cement companies use appropriate, resistant cement in their batches.

            Shade south and west facing walls. Some research in the past few years has indicated that shading the south and west facing walls, not the roofs, helps to reduce energy consumption of buildings situated in desert landscapes. This can be accomplished with trellised vines, shrubs or well-placed trees.

Using large trees in desert landscapes to shade is questionable due to water use
            Use trees that are in scale with the building. Large trees use more water than smaller trees. Even if a large tree is a so-called low water use tree, a smaller tree that might not be as water efficient may save water in a mature landscape. Water use rises dramatically with tree canopy volume. It makes no sense at all to plant a 40 foot tree to shade a one story building in our desert environment. Our main problem is to find good, small trees for small residential landscapes. More attention needs to be paid by our nurseries to developing some of our reliable large shrubs as small, specimen trees.

Ikebana floral designs use spaces creatively
            Use open spaces creatively. You’ll never save water by covering the soil with a plant canopy. The desert doesn’t do it and neither should we. Instead it is the challenge of a good designer to find creative ways to use open space. In Las Vegas of the past, if the designer had bare ground, they covered it with turfgrass. That time is gone and most people now realize that 100 percent turfgrass cover is irresponsible in our desert climate. Use turfgrass as a functional landscape planting, not a groundcover. It may be used to surround trees and shrubs that don’t do well under drip irrigation.

            The temptation might be to replace turfgrass with a green, desert groundcover like myoporum. That would be a mistake. Recent research in Las Vegas has demonstrated that myoporum uses over thirty percent more water than high maintenance bermudagrass. Play it safe. Be creative. Open spaces don’t use water.

            Consider hardscapes (boulders, covered patios, artwork, bridges, masonry, gazebos, fences, archways, benches) as alternatives to unnecessary plants in the design. Hardscapes don’t use water. Can a piece of hardscape be used to create shade instead of a large tree? Can it act as a focal point? Save plants for important items in a landscape and make them count. Plant use should be questioned if they are acting as a landscape filler.

            Incorporate elevation changes in the design to create interest, create areas in the landscape to collect water and protect sensitive plants. Elevation changes provide niches for plants that might not survive normally.

            When landscaping or relandscaping, a conscious effort should be made to follow the lead that deserts provide for us. Observe their characteristics and mimic them in the landscape. The house or building is situated in a “minioasis” in the desert landscape where it is protected from the harsh elements. Here it offers a retreat providing recreation, safety and comfort for the desert dweller.

Checklist: What Should I Consider in a Design That Will Add to the Quality of Life in a Desert?

How can I channel available breezes into living areas
What are my solar angles and where is the sun shining from during the summer
How can I control prevailing winds that are a nuisance
Will there be glare into windows from my design
Can I do anything to reduce dust problems inside the home
Where do I need focal points and splashes of color
How can I create interest with bare ground or “negative space”
What kind of microclimates am I creating with my design
What kind of spaces am I defining with my design and are they functional
Am I creating areas of recreation and areas for leisure activities
Am I creating shady spots for play areas, parking, patio, deck
Am I shading the windows
Am I considering attracting wildlife through the design
Am I avoiding allergy plants
Am I creating a safe design sensitive to the family’s needs and concerns
Am I addressing their privacy concerns
Am I stimulating all the human senses, not just sight

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