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Water-Efficient Landscaping in the Intermountain West
A Professional and Do-It-Yourself Guide
Utah State University Press
Copyright © 2011 Utah State University Press
All right reserved.
ISBN: 978-0-87421-789-6
Chapter One
Principle 1 Planning and Design Anne Spranger and William A. Varga
The design of a landscape is critical to achieving water sustainability. Landscapes must be designed to match the regional climate and soil conditions. These factors determine the amount of supplemental water that will be needed at a site. Ideally, the landscape should be designed so that the right plants are planned for the right spots, and plants with similar needs are grouped together so the need for supplemental water is minimized.
The first step in achieving this goal is to have a well-thought-out plan.
Program Development
Program development is an important first step in designing a successful water-efficient landscape. This step involves meeting with the client and discussing their landscape needs. This may include both the aesthetics and functional requirements for the landscape. This is a written exercise. Talk to the client and make a list of landscape goals and objectives. Determine activities, use areas, circulation elements, and related facilities that are desired in the final landscape. The available budget and desired water savings should be included in this discussion. The following are topics for consideration during a client interview:
• ACTIVITIES AND USE AREAS: What activities are planned for this landscape? Activity areas for a residential homeowner might include space for outdoor dining and barbecuing, children's play, vegetables and herbs, specialty gardens, a fruit/ nut tree grove, pets, storage, and composting. • CIRCULATION: How will the flow of traffic through this landscape be controlled? Circulation elements define the flow of traffic through a landscape. They should be both functional and aesthetically pleasing. Evaluate existing conditions and future needs for automobile access and parking, front entry walk design, and all secondary or tertiary paths. • HARDSCAPE: Evaluate existing conditions and future needs for hardscape elements such as patios, decks, courtyards, and shade structures. How do hardscapes in this landscape connect with planted areas? • IRRIGATION: Does the client want an automatic irrigation system? If so, how much of the budget can be allotted to this? Is the client interested in water harvesting: roof collection systems, rain barrels, or underground water-collecting cisterns? These systems allow a homeowner to collect precipitation water and either divert it to a planted area or store it for later use on the landscape. They conserve water by preventing evaporation or runoff from the site. (Check with your local county planning office to ask about zoning ordinances for water rights issues.) • PLANT SELECTION: Does the client have favorite plants, favorite colors, plant allergies? Does the client desire a lawn? Determine planned use for a lawn and how big it needs to be. Limit turfgrass to areas where it provides a functional benefit. • SPECIAL CONSIDERATIONS: Does the client have unique needs that need to be considered? Talk to the client about various topics such as desired maintenance levels, landscape lighting, ADA compliance, and ages of family members.
There are many other subjects that can be discussed with the client (see the Client Questionnaire Checklist at the end of this chapter). When the designer understands the client's needs, the resulting water-efficient landscape will be more successful.
Landscape Styles
A water-efficient landscape can be any style. It can be formal or informal, historic or modern, native or non-native; it can even have a theme if desired, such as a children's garden, a fragrance garden, or a pollinator garden. In general, landscape style should be influenced by the region and climate of the site, the architecture of the buildings, and of course, the client's preference. A combination of landscape styles may also be used if one style does not suit the site or client.
Formal and Informal Landscapes
A formal water-efficient landscape may have the appearance of a formal conventional landscape, which suggests a control of nature through its orderly, symmetrically balanced grouping of elements. Plants are often used to reflect the geometry of building architecture or the lines of streets and walkways. Planting areas and circulation elements are often straight and rigid. Plants are generally chosen for their formal, stiff, or manicured appearance. For example, formal landscapes may have edged lawns and neatly hedged shrubs. Keep in mind that formal landscapes often require a higher maintenance level than do informal landscapes. Clients should be advised about this; if they are unwilling or unable to perform these more demanding maintenance tasks, they should consider whether hiring labor for landscape maintenance is within their budget.
On the other hand, an informal water-efficient landscape is less geometric and uses asymmetrical balance. Planting areas and circulation elements tend to be free-flowing, incorporating curvilinear or irregular shapes and lines. Plants in an informal landscape may be maintained to accentuate their natural form.
Naturalistic Water-Efficient Landscapes
A naturalistic water-efficient landscape is designed using a very different approach from that of a formal or informal design. While form, color, and texture are still important for plant selection, the plants in a naturalistic design are generally native plants, and are grouped according to their natural associations or plant communities. Creating a sense of place and a sustainable landscape are of primary importance. A water-efficient naturalistic design for the Intermountain West could mimic natural plant communities in the region such as foothills, mountains, prairies, valleys, or deserts.
Maintenance for a naturalistic landscape is very different than it is for a formal or informal water-efficient landscape. Perfectly manicured lawns and sheared hedges are not found in the natural landscape, and are therefore not encouraged in a naturalistic design style. Spread of perennial plants in a naturalistic landscape may be desirable and promoted, and plants are often chosen for their capacity to provide habitat for wildlife and pollinators. Recycling nutrients by way of composting discarded plant parts and meeting water requirements by limiting water use to natural precipitation are sustainable methods for maintaining a naturalistic water-efficient landscape.
Site Inventory and Analysis
The second step in designing a successful water-efficient landscape is to become familiar with the site in order to determine its opportunities as well as its constraints. The following types of questions should be answered:
• What types of soil, drainage, exposure, and climatic conditions exist on the property? • Are there areas that require screening, either from the sun or wind, or to conceal poor views? • Where are the hot, dry areas on the site? • What kinds of plants will grow well on the site? • Do steep slopes present erosion or runoff problems? • What areas of the site are well suited to accommodate the client's needs and activities? • What is the best way to conserve water on this site? • Where and how is water being wasted on the site? Current water waste and its causes (see "Principle 6: Irrigation Planning") Start with a scale drawing of the property to be landscaped. Take note of all existing site conditions. Important landscape elements to inventory and analyze include the following: • SOILS: Determine soil type and its water-holding capacity. • TOPOGRAPHY: Determine percent slope, drainage, and erosion potential. • VIEWS: Take note of desirable and undesirable views from both inside the building and from the neighbors' point of view. • EXISTING VEGETATION: Determine what existing plants will be kept, moved, or removed. Determine weed abatement strategies. • CLIMATIC INFLUENCES: Determine high and low temperatures, annual precipitation, prevailing wind directions, and frost pockets. • EXPOSURE: Determine where sunny and shady areas are in the landscape. • HARDSCAPE: Take note of all existing hardscapes. Note materials, condition, and design. Determine what to keep and what to remove. • UTILITIES: Have all utilities marked before digging begins. Utilities to map include power, gas, water, sewer, telephone, and cable. Note whether utilities are buried or overhead, and note buried depth or overhead height. • ADJACENT PROPERTY: Take note of views, erosion potential, excess water runoff, or any other special conditions that may affect the client's landscape.
Take special care to consider all factors that contribute to dryness, including soil type, soil drainage, sun exposure, and climatic influences. Designing a successful water-efficient landscape begins by knowing what you have to work with.
Concept Plan
The third step in designing a successful water-efficient landscape is to start designing. At this point, the designer has collected information about the site and the client's goals and objectives. Next, the designer develops a concept plan. The purpose of a concept plan is to study appropriate locations and sizes for the various activities, use areas, and circulation elements that were identified in the program development and site analysis. A concept plan is drawn freehand; bubbles of various shapes and sizes are used to broadly depict the functional areas within a landscape and how they relate to one another. These drawings are meant to be rough estimates of the use of space at a site. Several concept plans should be drawn in order to find the best solution for a particular site and client. Once a concept plan is finalized, the use areas and circulation elements are converted into specific ground pattern shapes. Ground pattern is also commonly referred to as form composition.
Form Composition (Ground Pattern)
Form composition involves creating a specific edge, shape, form, and location for all spaces generated in the concept plan phase. For example, an area that represents the patio on the concept plan is now ready to be given a specific shape. It could be given a formal rectangular shape or perhaps a more informal curvilinear shape. The lawn, planting beds, garden paths, walkways, patios, and decks need to be given a definitive shape.
Form composition also helps to create consistency and continuity throughout a landscape by the repetition of particular forms. These forms or shapes may be angular, rectilinear, curvilinear, arc/tangent, or radial concentric. The choice of specific ground patterns may be based on the desired garden style or character, the character of the site, or the client's personal preference. Defining the form composition is a crucial step in the design process because it directly affects the visual appeal of a space. Visual appeal is enhanced by considering the geometric relationships between linear and circular elements within a form composition. The landscape designer should create at least two or three different ground pattern options for the client to review. Form composition will also influence maintenance and irrigation issues. A complex lawn shape can be challenging to mow and very difficult to irrigate efficiently.
Water-Use (Hydrozone) Zone Plan
It is essential to create a water-use plan for a water-efficient landscape. Water-efficient landscaping takes advantage of the varying conditions and microclimates that exist in every landscape. A microclimate is a small area in a landscape with a climate that differs from that of the surrounding area due to differences in sun or wind exposure, elevation, or soil characteristics. Use healthy, well-adapted plants, and hydrozone the landscape by grouping plants together that have similar water needs. It is important to place the right plant in the right location. Avoid planting a high-water-use plant next to a low-water-use plant. Many plants may be used in more than one water-use zone. Site-specific soils will affect water use. Heavy clay soils will require less frequent watering, while sandy soils may require more frequent watering.
Water-Use Zones (Hydrozones)
Very Low Water
This is the lowest-water-use zone in a water-efficient landscape and will provide the greatest water savings when compared to conventional landscaping. Plants used in this zone generally need no additional water once established. Supplemental water may be necessary only during extreme drought conditions, and this could be provided manually. This zone is often placed farthest from the residence because it does not need connections to irrigation pipe to support it.
Low Water
Plants used in the low-water-use zone need more water than the natural precipitation our region provides. Approximately one-half inch of water supplied once or twice per month should be sufficient. This amount may vary from site to site. Careful selection of a low-volume irrigation system will conserve large amounts of water (see "Principle 6: Irrigation Planning"). However, many people prefer to conserve additional water and water this zone by hand, as needed. Low-water-use zones should be as large as possible in order to maximize water conservation benefits.
Moderate Water
Moderate-water-use plants generally need about three-quarters of an inch of water supplied once per week. This is more than the low-water-use plants require but still 50% less than that required by most conventional landscapes. Remember that site-specific soils may affect water requirements. Plants in heavy clay soils may need less frequent watering, and those in sandy soils may need more frequent watering.
High Water
The high-water-use zone should be kept small in size and functional in use. It could be considered a mini-oasis and is best used when incorporated carefully into your landscape design. Kentucky bluegrass lawn is generally the primary plant used in this zone. Many annual flowers may also be considered high-water-use. Approximately one-half inch of water supplied three times per week is necessary. The high-water-use zone should be located close to the residence to minimize the length of pipe needed for irrigation.
Planting Design Plan
Landscape design combines elements of art and science to create a functional and aesthetically pleasing outdoor living space. The water-efficient landscape designer must understand the principles of artistic design as they apply to both plant materials and hardscape solutions. Many beautiful trees, shrubs, perennials, and ground covers are available for use in a water-efficient landscape. When selecting plants for the water-efficient landscape, the following characteristics should be considered:
• Cold hardiness • Water use • Drought tolerance • Resistance to pests and disease • Mature size • Color • Form • Texture • Leaves • Flowers • Fruit • Year-round interest • Maintenance needs • Availability • Cost
Plant Function
Plants function in many different ways in the designed water-efficient landscape. They may serve as a structural architectural component, an engineering component, or as climate control. Of course, the beauty and aesthetics of plants should be considered as well.
Plants and Structure
Plants can be used to give structure to a water-efficient landscape by defining spaces and creating outdoor "rooms." Trees and shrubs may be used to create walls, screens, or barriers. Ground covers and turfgrass can be used to create the floor of an outdoor room, while trees can create the overhead plane or ceiling.
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Excerpted from Water-Efficient Landscaping in the Intermountain West Copyright © 2011 by Utah State University Press. Excerpted by permission of Utah State University Press. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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