Water Wise Landscaping: Introduce Xeriscaping to your gardening Vocabulary

This is the seventh article in an eight part series intended to educate home buyers and builders on the different aspects of building “green."

Part I: Overview — Introduction to Green Building

Part II: Land Use Planning — Creating Value, Protecting the Environment

Part III: Material Science — New Options in Eco-friendly (and Healthier!) Building Materials

Part IV: Be a Miser — Strategies for Slashing Your Energy Consumption

Part V: A Drop in the Bucket — Painless Ways to Reduce Your Water Use

Part VI: Breathe Easy — Controlling Pollution Inside Your Home

Part VII: Xeriscaping — Drought-resistant, Low-maintenance Landscaping

Part VIII: Greening America — Green Certification and a Look at the Costs

The recent drought left its mark on the landscapes of the Triangle. Lack of rain, coupled with watering restrictions left manicured yards with brown lawns and withering shrubs. Whether you are developing a new landscape or renovating an existing one, there are solutions that can not only go a long way toward ensuring drought survival, but will also yield a landscape that is less expensive and time consuming to maintain.
 
Water restrictions are likely to be a permanent state of affairs in the Triangle, and with them, a new interest in a concept that has been gaining attention worldwide—xeriscaping. From the Greek, xeros, meaning dry, the term was originally conceived in the Southwestern U.S., although it was inspired by the gardening traditions of Spain, North Africa, and the Middle East and by the natural landscapes of the Southwest. Xeriscaping is a comprehensive landscaping strategy that strives for lush, colorful landscapes that have minimal water requirements.

Proper planning and design, with careful site preparation, plant selection and placement for your individual site is essential to achieving a lawn and garden that will thrive with the most minimal water demands.

“Before you even think about plant selection, a comprehensive site assessment is the first step to a drought resistant landscape,” says Dennis Werner, director of NC State’s JC Raulston Arboretum. “A plant that is drought tolerant may still not perform well if it’s planted in an unsuitable location or in poorly drained or compacted soil.” Healthy, vigorous plants are much better prepared to survive the stress of water shortages, and proper placement, in an environment that promotes strong root growth, is just as important as selecting species that, by nature, require less water.

Site Evaluation

Homeowners should evaluate their site for exposure and soil characteristics (pH, mineral content, drainage, and compaction). Soil compaction is an especially troublesome problem in new construction, where heavy equipment can create a hardpan that greatly hinders root development. A landscape contractor can perform sub-soiling, which is pulling a chisel plow through packed soil to break it up. “It’s really best to avoid compacting the soil in the first place,” comments Werner.

“Builders are becoming more conscious of limiting the movement of heavy equipment on building sites to areas that will not be landscaped, like driveways.”

Likewise, if topsoil has been removed during construction, bringing in new soil may be necessary to creating a healthy growing environment. Amending poorly drained soils with compost or other organic matter may also be necessary. Sta-Lite is a North Carolina produced additive made from baked slate. These pea-sized granules can greatly improve the aeration and drainage characteristics of soil.

The next step to creating a water-wise landscape is careful planning. In general, it’s best to work with the natural topography of your site. Forcing artificial grades can result in a landscape that requires both more water and more maintenance.

Study your light exposures and plan for plantings appropriate to the sunny or shady areas. Creating shade, where it may be lacking, is another tool in the xeriscaping arsenal. Shade acts as an effective guard against moisture loss, significantly reducing watering requirements.

When planning the overall design for your water-conserving landscape, try to think of turf as an accent and not the dominant feature of your outdoor space. The typical yard in the US is characterized by large expanses of water-guzzling lawns. Limit turf to areas that will bear traffic, and select grasses that require less watering. Bermuda grass is a warm-season grass that is drought tolerant and forms a dense, green carpet. Zoysia is another warm-season grass that is highly drought tolerant. Cold-hardy and wear-resistant, Zoysia makes an ideal full-sun lawn. For shadier areas, choose Centipede. This apple-green grass grows well in full sun to partial shade and has low fertilization requirements.

Adjust your lawn mower blade to at least three inches. A lawn cut higher encourages grass roots to grow deeper, shades the root system, and holds soil moisture better than closely-clipped lawns.

Oasis Design
 

Zoning your yard, which is grouping your plantings according to watering needs with the highest consumers being the smallest grouping, creates watering “zones” in the garden. This allows you to limit the most heavy watering to just a few small oasis areas. Plan these oases for areas with the most visual impact, like entries, primary views, patios and courtyards.

Xeriscaping does not mean no watering. It does mean making the most of the watering that you do. Some experts estimate that more than 50% of landscape water use goes to waste due to evaporation or runoff caused by overwatering. Drip irrigation systems use between 20 to 50% less water than conventional in-ground sprinkler systems. They are also much more efficient than conventional sprinklers because no water is lost to wind, runoff, and evaporation.

Avoid watering during the heat of the day (9:00 a.m. to 6:00 p.m.) and on windy days, when water is lost to evaporation. Install a rain sensor on automatic irrigation systems to conserve water when rainfall has been adequate. This relatively inexpensive device collects rainwater, overriding the automatic timer, and then drying out to allow the system to return to its normal setting.

Always water deeply to promote deeper root growth. Watering deeply, without wasteful runoff, means watering slowly. Gator Bags, placed at the foot of trees and shrubs, enable a slow four-to-five hour soak. These are especially useful for newer plantings that require more water until they are established.

Another excellent strategy for reducing water demands is harvesting and storing rainwater. Local builder, Rex Bost has spent the past decade perfecting a system for collecting, storing, filtering and distributing rainwater runoff. His Free Rain solution captures runoff from impervious surfaces like the roof and driveway. (A 2,500-square-foot roof will shed almost 70,000 gallons of water in just one year’s time.)

The Free Rain system utilizes underground storage tanks for collected water. These sealed tanks remain free from evaporation, insects and algae. Three phases of filtration ensure a sediment-free water supply that won’t clog irrigation heads. Harvested rainwater has the added advantage of being free of the chemicals used to treat municipal water—chemicals, like ammonia and chlorine, that can be harmful to plants.

Choose Wisely

Selecting drought-resistant plants is key to successful xeriscaping. While native plants are a very good choice, as they are well-adapted to this climate, many exotics have been bred for drought-resistance as well. “In the built environment, sometimes a site has been so dramatically modified that it is no longer native in its characteristics,” says Dennis Werner. “Native does not always mean the best adapted to the particular environment.” Werner cautions homeowners to avoid species with invasive potential when introducing non-native plants to the landscape. Reputable nurseries will not carry such species, and the U.S. Department of Agriculture publishes a list of noxious weeds and invasive plant species.

Some drought resistant trees recommended by Werner include the many varieties of redbud. Oklahoma is a Texas redbud that is particularly tolerant of scarce water. Cornelian cherries offer yellow blooms in early spring, and the Maindenhair tree features beautiful fall color and is tolerant of compacted soils. The Asian fringe tree is very well adapted to our climate and, with pruning, can grow to a lovely multi-trunk tree, up to 30 feet in height.

Drought-tolerant shrubs to consider include Chinese abelia with its mid-to-late summer blooms, yaupon holly, tea olive and butterfly bush (especially Blue Chip). Some varieties of hydrangea, like Limelight, are also drought resistant.

Once you’ve got all those plantings in the ground, don’t forget one of xeriscaping’s number one water conserving strategies—mulch. Mulching is essential to greatly reducing evaporation of moisture from the soil, as well as controlling weeds (Weeds are notorious water stealers in the garden). Mulch to a depth of 2” to 4” with pine bark or pine straw. These are readily available, and their slow decomposition contributes nutrients to the soil. But don’t allow mulch to build up over time to more than 4 inches, as this can cause the development of shallow root systems, which will dry out and more quickly be damaged. Never put mulch up against the stem or trunk of a tree, as this invites bacteria and fungi, which may cause diseases.

Healthy plants are drought-resistant plants, but there are some fertilizing considerations when dry-spell tolerance is a goal. Using phosphorous helps to develop good root systems for drought resistance, whereas nitrogen encourages foliage growth. Never feed plants during a drought, nor should you prune them as both stimulate new leaf growth.

A little groundwork, some planning and forethought in plant arrangement and selection, judicious watering (including making the most of every drop of rain) and fertilizing and a generous helping of mulch, and your yard and garden will stay green and beautiful through the even the hardest, driest summer. 

KELLY MCCALL BRANSON IS A FREELANCE WRITER