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Layering the Garden

Layering the Garden
ARTICLE BY: AMY WHITWORTH
Amy Whitworth is a garden designer and owner of Plan-it Earth Design in Portland, Oregon since 1998. She teaches Naturescaping & Rain Gardens for E. Multnomah Soil & Water Conservation District. She is on the board of APLD Oregon as legislative advocate protecting the rights of landscape designers in Oregon for way too many years.

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You know that feeling when you walk through the forest? It surrounds you and activates all of your senses. It makes you feel good. The Japanese have a name for it: shinrin-yoku or forest bathing.

In the Pacific Northwest, as we look to nature for inspiration, we can use the forest as a model for the way we organize and care for our gardens. We can recreate the magic of the forest by layering plants. From the tallest conifers and deciduous trees, to the smallest groundcovers and everything in between, layering is one way we can create sanctuary and a sense of intimacy with the place we live. No matter what size your property, it’s easy to start with your largest tree or shrub and layer down from there.

Layering the Garden

Laura & Charlie Heldreth Garden / Photo by Alyse Lansing

Fit in more and varied plants

Layering the Garden

Laura & Charlie Heldreth Garden / Photo by Alyse Lansing

Sometimes described as canopy layers, you can put any plant into a category based upon height. When viewed as a whole, a forest may contain all of these layers but not necessarily all in the same spot. The tallest trees are known as the overstory, and you can think of them as the roof of your garden. These are the trees that are larger than our homes and give our neighborhoods context. They may be the heritage trees we associate with a certain place. They are landmarks. Next in line come the understory trees, those that are commonly associated with urban spaces. These are considered small trees and might approach the height of your house. You can think of them as the ceiling of your garden room. Below that you’ll find the arborescent shrubs; those large shrubs you may prune into a tree to become a focal point of the garden because their flowers or foliage color, structure, fall color or bark attract attention. You might use these to create definition in the garden or to create privacy from neighboring homes.

Within the shrub layer are both medium and small shrubs that might vary in height from 10’ to 3’. This is a very important layer for baby birds as they learn to navigate their world with undeveloped wings. Most of the woody plants in our gardens fall into this category. This is the layer closest to us in size and is the layer we most interact and do our pruning dance with, clipping a little here, letting another grow there. On a small property, this is the layer that takes up the most of our precious space so we often must make difficult editing choices. Form becomes essential as we might choose columnar shapes for the taller plants, or dwarf versions of round ones, or choose to eliminate one of these layers altogether.

Below these various canopy layers will be the annuals/perennials, grasses, ferns or herbs/forbs where we find our favorite flowers and foliage plants, as well as our vegetables and other small and useful plants, including those in containers. You might consider these the furnishings, easy to move around and change like the pillows on a couch. At the lowest canopy level is where we’ll find the groundcovers which are the soft floor of our own personal forest.

Layering the Garden

Bebernes Garden / Photo by Alyse Lansing

Create shade

I always suggest to my clients that we try to include the largest trees that are appropriate for their landscape. Big trees are a valuable commodity in the city. They provide clean air for us to breathe; they drink up copious amounts of stormwater throughout the long rainy season, reducing reliance on infrastructure like pipes and drains; they reduce the “heat island effect” of the city streets and rooftops; they cut energy costs with proper placement by decreasing the need for air conditioning, they lower the temperature beneath their leafy canopy and provide a place of solace. As urban density increases, it becomes harder to find places for the titans of our urban forest canopy. When space allows, especially in corners where properties meet and far enough away from buildings and other obstacles like utilities to not become a hazard over time, consider adding an interesting large scale conifer or unusual shade tree and treat the whole neighborhood to an enchanting view from their windows.

Layering the Garden

Eloise Carson Garden / Photo by Alyse Lansing

Increase habitat for birds and other wildlife

The Backyard Habitat Certification Program (www.backyardhabitats.org) provides lots of guidance on the value of canopy layers. From the tippy top of the tallest conifer where you may see a bird precariously perched to the density of a thick shrub alive with sound in the winter to ground feeding birds scratching their way through debris left in the fall, birds will find a variety of places to act as a lookout for others in the flock, find shelter from the weather and from predators, locate the perfect nesting spot and raise a brood, or forage for food in the form of insects, nectar or berries.

Native wildlife (and pollinators) create special relationships to the native plants they have evolved with. The timing of migration coincides with the food that is sought. Most of our native insects are specialists and require the support only a specific native plant will give them (think milkweed and monarch butterflies). Certain species like our native Ninebark or Elderberry support various stages of local butterfly life cycles and other native species like Bitter Cherry or Garry Oak support a larger variety of birds, insects and more. You get extra credit if your garden’s layers include native plants.

Layering the Garden

Portland Japanese Garden / Photo by Alyse Lansing

Reduce weeds and the need to mulch or fertilize

The more canopy layers we include, the more varied and interesting the garden gets, and the harder it becomes for weeds to get a foothold; less light, less weeds. Open spaces become occupied by chosen plants; each shape fitting with the next like a 3 dimensional puzzle. We get to play with the composition of plant forms, and play with the design elements of color, texture, repetition, unity and balance until we find a garden full of the plants we love, arranged in a way that makes us happy and fulfilled.

When the ground is taken up by plants in varying layers, they begin to create their own mulch through seasonal changes and it becomes no longer necessary to add more unless you remove the organic materials generated. No one mulches the forest, do they? It’s a self supporting nutrient cycle where fertilization is also no longer necessary. No one objects to less work. It’s an important consideration as we continue to age along with our gardens.

Layering the Garden

Adriana Berry’s Garden / Photo by Alyse Lansing

Create community for your plants

Plants living together in the forest have the same cultural needs of light and water but also support each other in sharing nutrients and soil microbiology. We can take a lesson from permaculture by planting a combination of nitrogen fixing plants, plants that bring minerals up from their roots deep in the soil to the surface as their leaves melt into compost, flowers that attract pollinators, and groundcovers that create living mulch. Companion plants that support one another, and might naturally grow together like they do in the forest, set up a natural system that makes gardening easier.

Bringing Nature Home

Layering is the best way to bring the tranquil sense of the forest to your home garden. Whether you are trying to create shade or privacy, layer your plants from top to bottom. If you want to welcome the birds, bees and other wildlife into your sanctuary, give them a variety of places and canopy layers to find refuge. If you’re trying to reduce the amount of weeding you need to do, fill your garden with plants of various shapes and sizes. If you want your plants to thrive, encourage them to support one another by planting them within an intentional community. Think of the space you want to create and layer accordingly. If you’re looking for privacy, layer densely. If you want a living space, leave out the middle layers. If you want to grow flowers or vegetables, leave out the overstory. But always work toward 3 or more layers whenever possible for the most diverse and self supporting system, like a forest. Now go for a walk in your garden and bathe in the sensory experiences it provides.

Layering the Garden

Gossler Farms Nursery in Springfield, OR / Photo by Alyse Lansing

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shinrin-yokuFor more information about shinrin-yoku, check out the new book on this topic by Timber Press: http://www.timberpress.com/books/shinrin_yoku/miyazaki/9781604698794

(featured photo at the top of the post of the Joy Creek Nursery garden by Alyse Lansing)


Categories: Expert Advice
Tags: garden habitat, garden layering, layering the garden, naturescaping

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