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 Through careful planning and execution, landscapes can be retrofitted to improve sustainability. Retrofitting a landscape starts with a site analysis. By their very nature, landscapes evolve over time. As a result, many landscapes grow and mature into a space different from that originally intended or are no longer maintained as originally planned. When this happens, the landscape should be redesigned to integrate resource efficiency (sustainability), site functionality, and aesthetics. Through careful planning and execution, existing landscapes can be retrofitted to improve sustainability. The goal of this modification is to minimize the landscape’s environmental impact and maximize the value received from the dollars expended.
This chapter will focus on design and management strategies and will explore options to change existing landscapes so they are more sustainable. In large measure, this chapter is about taking a critical look at existing landscapes and finding ways to eliminate problem areas to make the site more sustainable. Specific landscape design, installation, and management strategies are described in the other chapters of this text.
This chapter will discuss the following topics: Site analysis for retrofitting and identifying opportunities to improve landscape sustainability.
SITE ANALYSIS FOR RETROFITTING.
Site analysis of an existing landscape is different from site analysis for a new landscape design. However, one common element between the two is the need to understand the design intent. Working with the original landscape designer for the site can be a valuable first step in analyzing the existing landscape. The other specific elements to evaluate during the site analysis can be summed up by addressing three main questions: Does the landscape design still work aesthetically? Are there landscape maintenance issues? Are there problems with the infrastructure elements (sidewalks, driveways, parking areas, lighting elements, etc.)?
Q Does the landscape design still work aesthetically?
Because ornamental plants and lawns account for a significant portion of landscapes, it is important to determine how well the plants are functioning in the existing landscape. What follows is a list of specific plant-related questions that should be asked to determine if the design needs to be modified. Each question is followed by possible reasons why the issue developed and potential retrofit solutions.
Q Are key plants serving their purpose in the landscape?
Plants have a number of functional and aesthetic roles in the landscape. Functional roles include defining spaces, framing desirable views or screening undesirable views, impacting circulation patterns, controlling erosion, and deflecting light. When plants are used for functional purposes such as screening or hedging, it is important to allow the plants to mature into those functional roles. Plants that are serving a purely aesthetic role should be allowed to mature into their natural size and form. Sometimes careless and unnecessary pruning leads to oddly shaped and grotesquely distorted plant forms that do not enhance the aesthetic of the planting composition.
SOLUTION.
Appropriate plant selection combined with appropriate management strategies allows plants to fulfill their intended functional or aesthetic purpose in the landscape. (Editor’s note: A parking lot planting’s overall aesthetic design would be greatly enhanced if the shrubs were allowed to develop into their natural form and not sheared to unnatural shapes. The planting composition would be improved further by including ground covers to reduce the inputs (labor and/or chemicals) needed for weed control.)
Q Are plant sizes in the right proportion to each other?
Plants have variable growth rates, and, over time, these differences may become quite pronounced. One way to alleviate this problem initially is to combine larger sizes [5-gallon (20 l)] container or balled-and-burlapped stock of slow-growing plants with smaller sizes [4-inch or 1-gallon (10 cm or 4 l) container] of fast-growing plants. This should help the planting composition stay in the correct proportion throughout the early years of the landscape’s life span.
SOLUTION.
If, over time, the proportions have changed significantly, and some plants are just too large relative to others, plants can be selectively replaced. This is a more sustainable option to replacing the entire landscape. It may also be a better long-term solution than having to constantly prune large plants to keep them in scale. This type of pruning is not sustainable as it requires substantial labor inputs and it creates a large amount of green waste.
 When completing a site analysis of a landscape, important questions to ask include: Are the plants serving their purpose in the landscape? Are the plants in the right proportion to each other? Has there been attrition, inappropriate additions, or invasion of volunteer plants over time?Q Has there been significant attrition, inappropriate additions, or invasion of volunteer plants over time? Does order to the overall composition need to be restored?
As microclimates on a site change due to a maturing landscape, so, too, will the plant species that are best suited to the site. Loss of original plants due to attrition can be a major problem in older landscapes. In addition to these losses, the original planting composition can change significantly because new plants are added or volunteer plants have colonized the site. All three of these combine to create a very different looking design than what was originally intended.
SOLUTION.
The landscape may require major redesign and the inclusion of a very different plant palette than that of the original design. The new plants should be selected based on the current site conditions with an eye toward additional microclimate changes that are expected due to continued growth and development of the landscape.
Q Are there too many or too few annual flower beds?
Flower beds filled with annuals are a beautiful addition to the landscape. They are a great way to accentuate a driveway or a building entrance. But these plantings are resource (labor, plants, water, and fertilizer) intensive. Thoughtful design and incorporation of these beds in key locations can be an effective way to visually enhance the landscape.
SOLUTION.
Consider how to maximize the impact gained from these planting beds.
Locate them only in high-visibility areas; select plants that thrive with minimal inputs of water, fertilizer, and deadheading; and use mass plantings to maximize visual impact.
Q Are lawns used inappropriately such as on steep slopes, areas that are difficult to mow, or areas with poor drainage?
Often lawn areas are used as “filler” in commercial designs. They are relatively inexpensive to install, grow in quickly, and give an instant visual appeal. Unfortunately, it seems that little thought is given to the long-term maintenance needs of lawns, including watering, fertilizing, and mowing. Odd-shaped lawn areas make it difficult to do these tasks.
SOLUTION.
In some cases, a similar design aesthetic can be achieved by substituting ground covers for lawn areas. Consider replacing narrow medians, parking lot strips, and other areas that do not have high foot traffic with a low-growing ground cover= such as common periwinkle (Vinca minor) in fullsun areas or bugleweed (Ajuga reptans) in shady locations. Once established, the ground covers will require fewer inputs of water, fertilizer, and labor, making them an attractive and sustainable choice.
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