Ecological Landscaping Design Methods
Ecological landscaping, an of-the-moment term that I hear everywhere I turn, is simply gardening that begins with a site's ecology and then works to build a garden that enhances the space for both humans and wildlife. This new garden ethic has a few key tenets that appeal to our eye and sense of space and benefit wildlife.
When I'm designing a space, here is where I begin:
1. We Re-Create Vertical Layers
Creating an ecological hierarchy with a canopy layer, shrub layer, and ground cover mimics natural environments and provides habitat at multiple levels—and appeals to humans as a special enclosed space.
Tall trees create an overarching crown and define a space. They provide ecological services like cover, pollen and nectar, nesting habitat, and shade.
Beneath the canopy lies the understory—smaller trees and shrubs that bridge the gap between mature trees and the ground. This layer adds visual interest, appeals to our sense of security, and helps create "outdoor rooms" that garden designers always talk about. If you can't figure out what's wrong with your garden, which is full of perennials, it's likely lacking this crucial middle layer.
Completing the ecological triad is the groundcover layer, a living carpet that sprawls beneath the understory. Groundcovers, including perennials, add the most color and texture to a space. We focus on this layer the most, but it relies on the higher layers to ground the space. As for the ecology, perennials and groundcovers prevent soil erosion, retain moisture, and suppress weeds.
2. We Choose High Diversity
Nature uses a variety of plants within each layer. This diversity supports a broader range of wildlife, from pollinators to birds, and supports overall habitat stability.
From a human perspective, diverse plantings create interest each season and make those beautiful color combinations we all love. One flowering drift is lovely. Three is heaven.
From an ecological perspective, a range of species creates stronger, more resilient ecosystems. When one species gets hit by a pest or disease, other plants can often survive and fill the gaps, helping the ecosystem bounce back faster.
One significant benefit of plant diversity is that it naturally reduces vulnerability to pests. Diverse plantings attract beneficial insects—like predators, parasitoids, and pollinators—who keep pest populations in check. These predator insects balance booms of prey insects that could otherwise wipe out monoculture plantings.
The diversity doesn't stop at insects; different species have different root structures, depths, and nutrient needs. Plants with deeper roots reach water unavailable to shallower plants, while those with shallower roots help capture moisture near the surface.
3. We Plant Densely
Densely planted areas create all sorts of ecological benefits, from resilience to climate change to soil stability. Planting densely maximizes not only plant and soil health but also wildlife habitat.
Dense plantings offer our designs that overlapping leaf texture that creates interest and beauty in a space. See how a row of shrubs is boring, but various leaf shapes are so interesting?
The reality is that blooms last only a few weeks, where well-planned plant textures that overlap provide beauty from spring to fall.
On the ecological side, bare patches of dirt are vulnerable to erosion, drying out, or becoming overrun with weeds. When plants are packed together, their roots spread out in competition for nutrients and water, and in doing so, they help stabilize the soil, prevent runoff, and improve water infiltration.
Dense plantings shade the soil, reducing temperatures and protecting tender roots and new shoots from extreme heat. Plant leaves and mass also trap moisture, preventing the soil from drying out too quickly and helping it retain water during dry periods.
Dense plantings also support greater biodiversity by creating more varied habitats for insects, birds, and other wildlife. This boosts local biodiversity, which in turn helps improve pollination, pest control, and overall ecosystem health. In a dense, balanced plant community, harmful pests have less opportunity to establish themselves, and the plants are more resilient to stressors.
Dense plantings are also a great way to combat invasive species. When plants are closely packed, they shade out weeds and reduce the amount of space available for aggressive non-natives to take root. This can be especially important in ecosystems where invasives are problematic, as dense plantings can help re-establish a natural balance.
4. We Skip Soil Amendments (Usually)
You may have heard, "native plants in native soils." Native plants have adapted to the types of soils where they are meant to grow. Where we once amended and amended soils year after year, we only take this approach if soils are highly degraded.
Soil amendments typically include nutrients like nitrogen, phosphorus, and potassium. Over-amending can lead to an imbalance, disrupting the natural nutrient ratios that plants require. This imbalance may result in nutrient deficiencies or toxicities, or introduce invasive or naturalized non-native seeds. While organic matter is beneficial, too much can lead to compacted or overly porous soil, impeding water movement and root penetration. It can cause floppy, leggy, or disease-prone plants.
If your soil looks lean, like red clay, remember that some of the richest plant habitats are found in nutrient-poor soils. Plants in nutrient-poor soils often develop extensive root systems, usually investing more in root growth, which allows them to scavenge and extract scarce nutrients efficiently.
The challenge is determining: how native is your soil? Has it suffered years of degradation through farming or major distributions like building construction?
We often see soil structure as the biggest challenge to overcome. Soil has a delicate structure that affects water drainage, aeration, and root development. Heavy equipment disrupts this structure, and typically that’s when we step in.
5. We Consider Water Flow
In our area of the Blue Ridge foothills and "Hill City," many sites have sloping terrain and nearby waterways, which creates erosion, heavy runoff during storms and poor drainage, and areas of bare dirt.
If you have runoff, consider a solution in rain gardens, strategically designed depressions planted with native vegetation that capture and absorb rainwater. They act as natural sponges, slowing down runoff and allowing water to infiltrate the ground to prevent erosion.
Our goals often include a way to establish and maintain a healthy vegetative cover, including grass, shrubs, and trees, to help absorb rainwater. The roots of plants facilitate water infiltration, while the foliage slows down raindrops, preventing soil erosion. We choose hardy and quick to establish species to start this process.
Incorporating swales (shallow channels) and berms (raised areas) into the landscape helps redirect and slow down runoff. Swales can collect and channel water to specific areas, while berms act as barriers that impede the flow of water, promoting infiltration.