Author- Michael Ross, Assistant Professor, SITES AP, University of Tennessee
Overview
For Extension Master Gardeners as interested individuals and community educators, few things carry as much significance as our ability to advance sustainability and resilience in Tennessee communities through our landscape outreach, education, and demonstration. Whether dealing with food security, species and soil conservation, pollinator support, or human health and well-being, a clear understanding of these concepts by Extension Master Gardener volunteers as they relate to residential landscapes can make a positive contribution at the individual, residential, and community scale. The ecological benefit is foundational, but it is often the experiential element of landscapes that attracts and engages us. Ultimately, the experiences you are able to create and enjoy make a garden something more than a collection of plants. This chapter will introduce you to the key elements of the sustainability and the experience of residential landscapes.
From the Beginning
Landscape design combines art, science, sociology, psychology, history, and geography. It reflects the needs and values, as well as the science and technology of the societies where it is practiced. With origins in agriculture, landscape painting, and aesthetic movements, landscape design has come a long way from merely meeting the desires of the aristocratic landowners. The complexity of these design services shaped the profession of landscape architecture and is still reflected in its practice. The birth of an affluent middle class in the United States enabled the average homeowner to attain the designed landscape. After World War II and the expansion of single-family residences, the landscape professions also expanded. Lawn services, readily available horticultural plants, access to a wide range of seeds, and commercially available tools all shaped what we have come to think of as the home landscape.
Residential landscape design requires a comprehensive and wide-ranging set of functions. For much of the last century residential landscapes needed to merely meet the programmatic goals of the residents. Emphasis was placed primarily on functionality of outdoor space and aesthetics that were inherited or duplicated from a largely western European influence. This approach was not without its successes because it produced beautiful gardens, lovely estates, and some exceptional examples of design prowess. However, over time it became common for residential landscapes to consist of often prescriptive combinations of lawn, foundation plantings, and repetitive plant selections punctuated by a specimen tree. While many individuals installed beautiful, creative, and functional elements in their residential spaces, many similar landscapes were installed without adequate focus on ecology, function, or even beauty. With this approach, constant effort was applied to maintain a residential landscape that looked exactly the same year after year. Individuals, municipalities, and HOAs all pushed, intentionally or otherwise, for the standardization of residential landscapes. Too often little thought was given to meeting more expansive and aspirational goals such as conservation, stormwater mitigation, biodiversity, ecosystem services, and aesthetic and experiential richness.
Transformation of the Landscape Mindset
Starting in the 1960s, environmental thinking began to shift as writings such as The Sand County Almanac, Silent Spring, and Design with Nature started a renaissance in ecological thinking in landscape design, landscape architecture, and horticulture. Beyond authors, national figures such as First Lady Claudia “Lady Bird” Johnson pushed for the preservation and horticultural use of native plants as well as the re-examining of the role of landscape in urban design. These efforts led to a more holistic and inspired way of thinking about the designed landscape. We must still meet the practical shade, screening, and privacy needs of the residents with outdoor amenities such as kitchens, pools, fire pits, and pet and family play areas. However, we now better understand the importance of landscapes that provide a more comprehensive suite of services and benefits beyond the individual residence.
In 1987, the World Commission on Environment and Development: Our Common Future Report, otherwise known as the Brundtland Report defined sustainable development as “Meeting the needs of the present without compromising the ability of future generations to meet their own needs”. In more practical terms, sustainability has come to mean a balance in economic, social, and environmental needs and inputs. Residential scale applications, such as reduce, reuse, and recycle have made these sustainability or stewardship practices widely accessible. Beyond sustainability is the concept of resilience. In this discussion, it is the ability for a garden, landscape, or ecosystem to bounce back after a disturbance. This could be of either natural or anthropogenic (human-caused) origin, such as a wildfire, tornado, hurricane, or construction project.
Gardeners have the advantage of working with plants in their efforts to understand and support sustainability. Plants are regenerative by nature because they take energy from the sun and convert that sunlight into biomass that is available for other organisms to consume. This plant photosynthesis produces carbon and nitrogen-containing compounds that support a host of soil organisms and other plants without any input from humans. This is truly a sustainable system. While it is possible to have designed landscapes, even residential ones, without plants, the sustainability and resilience component would be much reduced. So, with this context and foundation, let’s look at ways to approach designing the home landscape with the goal of sustainability and resilience.
Sustainable Landscape Design and the Resilient Home Landscape
Residential landscapes need to be designed to provide for all users, human and non-human alike. The social, spiritual, economic, aesthetic, and ecological needs of the landowner make it possible to create a priority chart that allows budgets, material choices, spatial arrangements, and plantings to be strategically planned. It is not always obvious what these priorities might be, so it is often helpful to consult with a professional landscape architect or landscape designer trained in design as well as consultation and landscape planning. As an example, suppose a homeowner decided to put a large shop, garage, or outbuilding on their property. At first, they may go through a contractor and have the structure built, only to find out afterward that they now have a stormwater drainage issue. If their project had begun with a consultation with a professional landscape architect or a qualified landscape designer, the homeowner could have proactively addressed the drainage issue but also expanded their garden with the inclusion of bioswales and a rain garden.
Where to Begin- Site Inventory and User Needs
A comprehensive site assessment followed by a thoughtful analysis of what these elements mean to your desired project allows you to prevent problems during project design and implementation. Things to include in the inventory are official property lines, definitive site boundaries, and 811 call data, such as mapped utilities. Also, think carefully about easements, and any infrastructure concerns, such as septic or sewer lines, driveways, sidewalks, overhead power lines, and building foundations. It is wise to research municipal codes regarding vegetation, HOA restrictions, and invasive species and noxious weed lists for the region. The slopes and topography of the site are important. Do parts of the yard routinely flood? Will any digging cause your soil to wash down into your neighbor’s yard? How close are you to nearby creeks, lakes, or streams? The better you understand the conditions of your site and the constraints and opportunities for your project, the better the designed outcome and your satisfaction with the result.
It is extremely important to think about the needs and desires of the homeowner and residents on the property. Many gardens and landscape do-it-yourself manuals, social media videos, and garden programs have focused on the idea of meeting human needs. However, it bears repeating because no matter how ecologically sound your design, implementation, and management strategies are, if you don’t meet the needs of the resident, the landscape will not be sustainable. In the end, people have to love their landscape and want to be committed to it.
The commitment to aligning sustainable landscape design, implementation, and management can’t be overstated. These components must be addressed as a whole. How much maintenance and management are you willing to do yourself or hire someone to do? Are there individuals or companies available with the skillsets and training to successfully manage the landscape design you are planning? If you aren’t able to match the maintenance with the overall goals, the far-reaching sustainability benefits start to diminish. If your goal is to enhance species richness and functional diversity, but your landscape maintenance contractor mows excessively or utilizes improper pruning, weeding, or fertilizer application, the carbon footprint will increase as will the need for labor and other inputs, ultimately negating your design intentions.
After you have completed your initial inventory and analyzed what the information means in terms of design, implementation, and management, you can begin to let your mind explore the possibilities. It can feel overwhelming at first, but identifying some primary sustainability and resilience goals can help guide your design decisions. Here are a few common examples of primary goals and related benefits.
- Increasing the number of native plant species in your garden could begin by removing some of the more aggressive invasive plants on your property.
- Decreasing the amount of mowing could begin by exploring the possibility of establishing a meadow or pocket prairie. The meadow/prairie plan could emphasize the inclusion of larval host plants, high-quality nectar plants, and rich seasonal variation in flowering so that your landscape now supports a wide range of pollinators, insect species, and potentially bird species.
- Adding a rain garden could be initially interesting to grow plants that can handle periods of higher moisture than the rest of your landscape. But there are also the benefits of helping to reduce stormwater runoff, improving the natural subsurface hydrology of your soil, and functional ecology of your site. You have now taken steps to help mitigate future drought effects on your residential landscape.
All of these project types improve the sustainability and resilience of the landscape and enable multiple goals to be achieved in one project. They add variety in terms of space, time, and aesthetics. They add species richness, essentially the number of species present on the site, and they contribute to ecosystem services, the goods and services that healthy ecosystems provide people.
By taking the time to identify the kinds of projects that interest you and combining this with the knowledge you have of the site you can now start thinking about plant species, form and spatial qualities, and experiential richness. Now, the blank page doesn’t seem so intimidating and you can start laying out your ideas.
Landscape Architect or Landscape Designer?
Within the landscape professions, landscape architecture is unique in that it requires a license. This makes it a legally protected profession. Licensure is issued after the completion of an accredited degree in landscape architecture from a university, passing of the Landscape Architecture Registration Exam (LARE), and the completion of two years working under the supervision of a licensed landscape architect. Landscape architects are licensed to protect human safety and well-being because their scope of practice includes actions that could lead to human risk. For example, a soil failure on a site that causes a building collapse or a poorly designed intersection that results in serious car collisions. In comparison, landscape designers are not legally licensed, and their abilities vary based on experience, education, and focus. You can receive exceptional services from landscape designers and landscape architects or be disappointed in the results by either. It is important to vet the designer you are considering working with to make sure that you both are a good fit for each other.
Size Matters
Traditional approaches to landscape design called for creating evenly rich loamy soils with mineral inputs to adjust pH, amendments to increase organic matter, aeration and other techniques with the goal of producing an ideal location for a wide range of ornamental plants. Some might imagine a garden-scale version of container growing. The problem with that mentality or approach is that it is generally unsuccessful and is also cost-prohibitive on a large scale. Also important, it misses the mark on sustainability and resilience and ignores the many interesting possibilities for growing a wider variety of plants adapted to the site conditions. For example, no matter how much you try to amend to acidify your garden soil, if the parent material (the rocks, soil, and mineral base material), or your water for irrigation has a high pH, or the bed is next to a high pH walkway, driveway, or path, such as concrete, lowering the pH will always be a battle. All of these approaches to aggressively modify the site can turn into a ritual that is carried out in order to grow plants that would be happier somewhere else. If these important tasks are discontinued, your investment of time and material (plants, supplements, etc.) are wasted as your garden starts to fail. Consider a different approach. Here are some practical examples of utilizing the site inventory and analysis to design with the site instead of continually working against it.
- Consider a site with a western-facing, gradual slope and exposed limestone boulders. Rather than having the rock removed or trying to import enough soil to cover the limestone, consider the realities of the site. A western aspect will have dry, hot afternoon sun and the limestone parent material will tend towards a basic (high pH) and shallow soil. A planting bed or garden theme can be created around those conditions. Look at naturally occurring plant communities that occupy and evolve under these types of conditions. Then, select plants, materials, and circulation paths that showcase this unique condition. In Tennessee, the cedar glades of our region are good examples. These ecosystems provide excellent case studies of plant materials and approaches to design with this type of site.
- Shaded or low-lying sites could have planting designs that rely on the same ideas. Acknowledge the conditions of the site and look for plant materials that have adapted and evolved to those conditions. You will find that there are many native, and non-invasive adapted plants that can fill these unique niches in your sustainable and resilient landscape.
- The design for the plant palettes for a Tennessee green roof is another example. Depending on the pH tendencies of the parent material, you can choose plants that meet those conditions. For example, Tennessee Coneflower (Echinacea tennesseensis), Pennsylvania Sedge (Carex pensylvanica), Coreopsis, and Salvia sp., which prefer good drainage, and a variety of native and appropriately adapted ornamental grasses.
In each of these examples, the resident or client saved the money and headache of trying to rid their site or property of the unique character it has and found some well-adapted, tolerant, and durable plants to build a foundation for their garden or bed on. And, it would still be possible to expand the plant options by including containerized plants or hollowing out deeper planting pockets that can incorporate specimen plants. Working with the larger site while also still cultivating some unique or desirable plants that require slightly different conditions both help reach the goal of reducing the inputs of labor, energy, water, and chemicals.
Native and Adapted Plants
Native plants provide some key benefits for the sustainable and resilient residential landscape. Research has shown that native plants help support robust insect, pollinator, and other wildlife populations. Native plants also contribute to a sense of place and provide regional context. They have evolved over generations to meet the conditions occurring in your localities, and they tend to prefer native soils and lower fertility. Once established (herbaceous perennials 1-1.5 years, woody shrubs up to 3 years, and trees 5 years or more), native plants may not require irrigation provided the plant is matched with its ecological context and environmental needs. Another key reason to use native plants in your landscape is that many of the native plant communities that naturally occurred in these locations have been removed and replaced. Agricultural crops as well as lawn, landscape, and garden plants from Europe, Asia, and South America along with concrete, asphalt, and buildings now fill many of the spaces once held by native plant communities. While there have been major benefits from these changes in land use, the result is one that leaves much less room for the rich and unique biodiversity of native plants that once represented huge swaths of the United States. This is not unique to the US, it is a global issue, and one that the individual gardener can play a role in mitigating by including native plants in their designed landscapes and advocating for their inclusion in municipal, HOA, and state planting guidelines.
Adapted or appropriate plants include native and non-native ornamental plants that are neither invasive nor overly weedy. The average homeowner may not be aware of the economic and environmental cost of invasive species, and it is important that as a community resource on gardening and plants that we help educate them on these costs. According to the Tennessee Invasive Plant Council, more than $2.6 million dollars are spent annually on mitigating invasive plants in Tennessee. That doesn’t include all invasives, such as insects, fungi, and other diseases of plants and animals. According to the USDA National Invasive Species Information Center, invasive plant, insect, fungi, and other pathogen controls have cost over $1.2 trillion in the last 50 years. Again, while this is not exclusive to plant material, it does help illustrate why we want to be cautious and sensible about what we choose to plant, grow, or leave in our landscapes.
Beyond the issues associated with invasive plants, overly weedy plants result in excess work and inputs to control while contributing little to our sustainability and resilience goals. There are many beautiful, well-behaved ornamental plants that can play a role in our designed landscape. They can serve as specimen plants, pops of color, and experientially rich additions of fragrance and texture. All are possible with care in selection and introduction. However, the full impacts of introducing species are often not discovered until years later. For example, cultivars of known invasive ornamental plants have been bred to be sterile but may still be able to produce viable seeds. Bradford Pear was believed to be sterile when it was introduced in the early 1960s. However, once planted widely, it bred with other pear trees to produce hybrids that are greatly impacting native tree stands.
Ultimately, as stewards of the environment and active gardeners and designers, we want to use best practices and well-informed decision making to guide our projects. A general rule of thumb is to ensure that your sustainability and resilience goals include a plan for conservation and that the biodiversity goal is to include 70% or more native plants in your garden. That might include cultivars of native plants or even native plants serving in the role of fillers or living mulches in garden beds. One potential benefit of this goal is that money that would otherwise be spent on particularly unusual plants can go to the 30% exotic ornamental plants that flesh out the design. This allows the homeowner opportunities to be very selective and choose special plant material.
Some Design Basics and Additional Considerations
As mentioned before, there are many do-it-yourself guides to designing your home landscape and garden. Understanding and implementing design principles and elements including space and form requires more than a brief overview. The complexity of design is the reason why landscape design and landscape architecture are professions. However, an introduction to some key elements to consider when thinking about design can be an asset to gardeners. Three elements we will discuss here include:
- Experiential Quality
- Form and Function
- Livability
Experiential Quality
Imagine sitting out in your garden with a few close friends enjoying conversation and the cooling temperatures of upcoming fall. It’s late afternoon, and the setting sun provides perfect back-lighting for your white cloud muhly grass. The seed heads are glowing a bright white. A gentle breeze starts to pick up and the seed heads from the grasses start to sway back and forth. The fragrance of your buttonbush, growing at the edge of your nearby rain garden perfumes the site with a light, subtle sweetness. The last swallowtails of the season are flitting about between your border plantings. Their flight patterns provide eclectic trajectories that are both random and anticipatory. Many of the flowers in your garden are maturing into ripening seed heads. It won’t be long and the Gold Finches will be here devouring all of the seeds. The whirr of insects and the generally golden atmosphere of the garden in the transition between late summer and early autumn provide the calming backdrop for the visit with friends. All too soon the visit must end. As you all get up to say your goodbyes and walk your guests to their cars the crunch of the crushed gravel path sends everyone off with a smile….
The description above is the experiential quality of the garden. In design, the focus is often on the components. What plants, what colors, and where to add symmetry or curves? Those are all important, but the heart of the matter is the experiences you are able to create and enjoy that make a garden something more than a collection of plants. While you are considering whether or not to make the path straight or curved, consider whether you are able to create moments in the garden that showcase an experience, highlight a unique quality, or play with light or wind to employ movement, sound, or distribute fragrance around the garden. Paving materials have qualities all their own and can help set a casual and comfortable, or fussy and formal tone. They also can help to make a path feel stable or can become slippery in inclement weather. Different types of wood or stone can provide a visual or tactile warmth. Metals and plastics can provide a contemporary or futuristic sense of space. Sound, light, texture, and fragrance all play important roles in the sensory experience of the garden. They can also form crucial experiential components for clients with differential abilities to perceive olfactory, visual, and tactile stimuli.
Plants that have vibrant colors or coarse textures advance toward the viewer and can make small spaces feel constrained and overwhelming. Cool colors and fine textures retreat from the viewer and can make spaces feel larger or more expansive. This applies to sculpture, planting containers, paving patterns/materials, and furniture used in the garden as well.
Lighting can be used to spotlight, up-light, showcase, and delineate space, objects, and plants. Waterfalls, fountains, and even tall grasses that catch wind can set an auditory tone for the garden and help mitigate off-site noise concerns.
Illusory and abstract references, such as clustered plantings, or sculptural elements that hint at a famous painting or a poem, something that reminds your visitors of a favorite place or trip, can also be used as ways to showcase unique ideas, concepts, artwork, or as hidden references for guests and family members who are ‘in the know’.
These approaches aren’t always immediately apparent and may require adjustments over time to achieve the desired effect. But, when you have dialed in the experiential qualities, the garden truly takes on its own personality.
Form and Function
Landscape design relies on form, spatial relationships, and functionality. Function is especially important in the case of sustainable and resilient landscapes. Function too often is the primary focus, such as with engineering solutions focused on how much stormwater will be present and how fast that water is moving off-site. On the other end of the spectrum, function can be relegated to being largely unimportant because beauty is its own function. The problem is that both of these functional perspectives are needed in equal measure to achieve the desired level of sustainability and resilience. It should resonate with people and not spreadsheets, with ecology and biology and not merely painting canvases to hang in galleries.
It is not always easy to take something that often looks like a box or rectangle, such as a standard residential lot, and create beautiful movement in the landscape. It takes practice and patience. Consulting with a professional designer can make the process smoother and more rewarding in the end. It is important to think back on how the form and function contribute to the experiential quality of the design. If you have not set both as a priority in the beginning, you run the risk of losing out on one or the other. For example, you have designed a beautiful raised mound that you anticipate will be covered in wildflowers, and you hold that vision in mind as you lay out your lot and design the garden. Everything is set and then you realize that not only did you not leave enough space for the raingarden to accommodate the runoff from your roof but that the wildflower mound will now push the runoff from the downspout back into the house and foundation.
In the best-case scenario, this requires some moving and extending downspouts to avoid water accumulation near the foundation, but you may have missed a key opportunity to meet some significant sustainability and resilience goals. Worse, you might have to dig up and relocate your mound and alter the circulation in the garden to accommodate the design intention. Related to all of this is the management and maintenance required for the design you have envisioned. Depending on the form and the intended function, landscape management and maintenance should be a key factor in the design from the very beginning, which contributes to livability.
Livability
Imagine you are sitting in your garden with your friends as in our experiential example, however, the conversation is continually interrupted by your sneezing. You love the look of the garden, but you are allergic to grass pollen, you get hives walking past sunflowers, and you have a severe allergic reaction to insect bites. This garden is something you love but can’t simply live with. Does this mean no garden for you? No, it just means that the design should accommodate your needs. Instead of designing for outdoor enjoyment, you could plan the garden around views from the house, such as large windows or screened in or glassed porches to experience your garden during the seasons that are most uncomfortable. This allows you to live with your landscape and still derive joy from it. You make informed decisions about plant material based on pollen production and known allergies and decide what you can live with.
Let’s look at a less extreme example. You have a love of French formal rose gardens, but you do not have the time to care for and maintain the garden nor do you have access to the professional horticulturists you would hire to do it for you. Or, you love the idea of a big wildflower meadow in your front yard but the HOA or city says you cannot have vegetation over 12” high. You don’t have the time or patience to repeatedly show up to city council meetings to fight the fines resulting from your dream meadow. It is very difficult to have a sustainable and resilient landscape if it requires far more energy and effort than you can provide. In the end, it is not something that your lifestyle and time supports. Therefore, you can’t live with it.
All of these examples present practical realities that need to be considered at the outset. Before you have color theory dialed in or you select beautiful, imported, antique clay olive oil vessels to harvest rainwater or place famous sculptures to serve as termini for axes, you need to figure out the key components of experiential quality, form and function, and livability. There will be time later to include the unique accouterments that support these three key considerations.
Summary
Sustainable and resilient landscape design depends on holistic thinking about reducing inputs of labor, chemicals, and water. It requires deep consideration of conservation and biodiversity. It emphasizes species richness and ecosystem services. It seeks to reduce stormwater runoff and infiltrate rainwater into the soil where it is usable by plants. It places significant importance on native and adapted plants that meet the needs of wildlife and the aesthetic needs of the homeowner. Sustainable and resilient landscape design places importance on the long view and seeks to prioritize management over maintenance in order to more efficiently and responsibly steward our designed landscapes and resources. When these principles are thoroughly applied, the individual sustainable and resilient garden and residential site becomes part of a larger network of designed and built landscapes in your neighborhood, city, or region. Your biodiverse, conservation-oriented garden now works in concert with the pocket prairie your municipality installed in your neighborhood park, the outdoor classroom and science lab at the elementary school down the road, or your rain gardens and infiltration planting beds contribute to the stormwater mitigation swales your community is using to help alleviate flooding. Your knowledge and understanding of these systems can be shared based on firsthand experience as you engage in service and education in your community.