Sustainable Landscape Design

Sustainable? What do you mean sustainable? There is a certain mystique about that term, no doubt. Today’s consumer is more and more likely to request a landscape that is low input, environmentally friendly and, oh yes, looks great as well.

Consumer demand, then, drives what has become a current term for a concept that has been evolving for many years – the sustainable design. It’s a way for landscape users to have their cake and eat it, too. The issues addressed in a good sustainable landscape design are enhanced aesthetic appeal, low maintenance costs, less water and pesticide usage, enhanced open space and amenity value, and perhaps enhanced habitat value.

Why sustainable designs? Problems, needs, environmental concerns and budget restrictions, that’s why. All of these issues can be addressed with a sustainable design. The sustainable design is created with the mindset of common sense and horticultural knowledge. In short, sustainability in landscaping involves organizing and enriching outdoor space through the placement of plants and structures in agreeable and useful relationships with the natural environment. This framework sets the stage for the creation of space that blends aesthetics, function and maintenance considerations with existing landforms and parameters.

Why emphasize design at all? It’s a start, a plan, a purpose. The design provides a logical, organized framework for creating a solution to problems at hand. Sustainable design will aid in the determination of the best use and maximization of site features. When these factors are considered, outdoor space is created and enhanced, which maximizes the usefulness of the site.

THE DESIGN PROCESS. So, how does one get started with sustainable design? Many avenues are available, including starting from scratch or retrofitting an existing landscape. Whatever the approach, the key consideration is to choose plants that last. Good design is not about making a list of the client’s favorite plants and installing them all over the site. Rather, sustainable design is a creative, problem-solving process that usually involves seven stages:

1. Accept the situation
2. Analyze facts and feelings
3. Define goals and objectives
4. Generate ideas to achieve goals
5. Select "best" idea or combination of ideas
6. Implement ideas
7. Evaluate design

The seven-stage process is circular; it is ongoing and never ending. Feedback from the client, previous owners, growers, neighbors, subcontractors, etc., provides valuable input into the overall process of achieving sustainability. The circular process is extremely useful, ensuring that the design solution is appropriate by providing a basis for a discussion of various possibilities.

The existing parameters and land forms dictate the initial consideration of the process. The best place to start is with an accurate base map. The base map provides all of the necessary information regarding the permanent features of the area, including property lines, easements, building footprints, contours, utility locations, and existing plants. A north arrow and graphic scale must be included to provide reference when communicating the eventual design to customers and to retain accurate space relationships if the finished plan is reduced or enlarged.

The overall design concept of a sustainable design will determined the program. Quite simply, program components are a listing of wants and desires of the stakeholders of a project. Early on in the design process, they tend to be general. A typical program statement for a sustainable design would include things such as minimized turf areas, creation of ornamental beds containing native plants, screening with native trees, etc. Specific plants are chosen at the end of the design process, not the beginning.

The next step is a site inventory/analysis. This is best performed on site, gathering information, taking notes and gaining a "sense of place" in the landscape space. The inventory is first, an identification of problem areas as well as the assets of an area. Use a piece of tracing paper and lay it over the base map. This provides for accurate note taking and documentation of potential concerns or opportunities for features. You might want to photograph the area for future reference and comparison. If the finished design turns out well, you might want to use the before and after photos to sell a job to another customer. The analysis comes later, an evaluation of the importance of each specific condition. For example, the soils, neighboring views and existing buildings might be only a slight concern, but the slope and prevailing winds could be serious contentions.

A "bubble diagram" should be drawn after the program is in place and the site is analyzed. This will help put the written word into a visual format. Again, working on tracing paper over the base map, diagram the site according to function. Traffic flow, high-use areas, low-use areas, water features and so on are all components that should be drawn in at this point. Exacting detail is not necessary in a bubble diagram. Circles and ovals with a light colored shade will suffice. Concept drawings are then developed, combining the program considerations with the site analysis information and the original design concept for the project.

AESTHETICS, FUNCTION, MAINTENANCE. The sustainable design should enframe important views, such as lakes, parks, skylines and other vistas. In many cases, this can be accomplished with the creation of wall planes along property lines or between sections of the landscape. As the wall planes materialize, landscape depth should be developed. This is done by incorporating large shrubs and small trees in front of taller ones, smaller shrubs and hedges in front of the small trees, and groundcovers and perennials in front of the small shrubs. If this is implemented, the space takes on a "layered" appearance.

Sustainable designs are much more aesthetically pleasing if space is defined clearly and simply. In large landscape spaces, berms and existing landforms, such as rock outcroppings and stream banks, can create space. Of course, space definition can be achieved through plantings and man-made structures as well. When choosing the plants, keep year-round interest in mind. This is especially important for southern and transition zone landscapes, yet northern sites need at least three-season interest. The presence of small fruits, attractive bark, interesting seedheads and dominant textures can be quite attractive to users of the landscape.

The most powerful design element for sustainable landscape design is mass/void. Because of the dominance of turf in the traditional landscape, when relatively large ornamental beds are installed adjacent to large turf expanses, the ornamentals become the mass, and the turf, the void. Plants should always be massed when practical to avoid a lonely look to a solitary shrub or flower. When smaller masses are implemented, be sure to use odd numbers to avoid distraction to the landscape user. Even numbers of specimens present a natural "puzzle," one that the user of the landscape may attempt to solve by dividing the even number in two.

Repetition of landscape elements can be helpful aesthetically as well as from a maintenance standpoint. Using more of less tends to unify the overall landscape, creating a more pleasing look than using entirely new plants in each section of the landscape. The plants chosen should be repeated, integrated and overlapped with others to create a sense of familiarity, yet maintain the clients’ interest as they move through the site.

A sustainable design must be functional as well as attractive. Microclimates identified in the site analysis must be considered, especially when plant selection takes place. Northern and eastern exposures, especially if shaded, create entirely different growing conditions for plant materials than western and southern exposures. Consider the number of hours of direct sunlight received, density of the overhead canopy, prevailing winds and soil drainage of the microclimate.

In general, turf must be separated from ornamental plants. The two plant types have drastically different moisture and fertility requirements. The sustainable design strives to group plants according to similar needs. Plants out of place are subjected to deficiencies or excesses simply because of location. Ornamental plants placed in the middle of turf areas are usually overfertilized and overwatered. Similarly, narrow strips of turf along side ornamental beds are difficult to mow, fertilize and irrigate, and tend to receive less care than they require. Instead, design beds for efficient machine use and place plants within beds whenever possible, minimizing scattered elements.

All plants require adequate drainage. Drainage is a priority in a sustainable design, and should be noted as a problem in the site inventory. Mitigation steps such as soil amendment and drain tile installation must be implemented to create good rooting conditions. Once the conditions exist for good plant growth, the sustainable design places the right plant in the right place. Placement and plant selection is crucial to the sustainability of the landscape. Healthy plants have fewer insect and disease problems, requiring lower maintenance from the client or the maintenance worker. Properly sized trees and shrubs need minimal pruning, drought tolerant perennials need minimal irrigation, etc.

Plant selection criteria are not only site related. Consider these criteria to the program statement. If a clean, kept turf is important, avoid plants with large persistent leaves, fruits or seed pods that will create an untidy appearance on the lawn. Genetic resistance to fungi and insects is just as important for ornamental plants as it is for turf cultivars. Plants that are naturally resistant to pests require much less maintenance than susceptible ones in terms of time and cost of control agents.

Sustainable landscape design requires the consideration of many factors in a comprehensive approach in order to reach the goals set forth in the beginning paragraphs. The wise landscape contractor will take the time and effort to inform themselves of the importance of the various facets involved in order to produce a final project that benefits all involved.