Planting the bones

LIKE A BEAUTIFUL FACE, a well-designed garden needs structure. But the bones of a garden are its layers of vegetation--trees, shrubs and groundcovers, possibly with other layers in between or above.

Just as there are standards that define a "classically" beautiful face, there are standards that define an aesthethically pleasing garden. Key among these is the requirement that a well-designed vista should have vegetation at at least 3 levels. In a flower border, this comes from having tall, medium-sized, and short plants. In a landscape, layers are typically provided by large trees at the top or canopy layer, small trees or shrubs at the middle layer, and by a ground layer composed of small shrubby groundcovers or other plants.

In the flower garden, structure comes from planting different sizes of annuals and perennials. For height and plain old cheerfulness, nothing beats sunflowers, as shown in this garden painting by Monet.

In the landscape, trees, shrubs, and groundcovers bring structure to the scene. This painting by Van Gogh shows a garden with at least four layers of vegetation (a large tree, many small trees and shrubs, a planting of perennials, and lawn). He's also added structure using man-made objects: benches, gates, and buildings. For instance, the church tower in the distance on the right echoes the tall tree on the left, creating a canopy layer for this design. The garden gate on the lower right side completes the middle layer.

Happily, multiple layers are also good for birds and other wildlife. Different animals "specialize" in different layers of the environment. Juncos, for instance, feed and nest near the ground, whereas other birds tend to hand out in the middle layer and some will be found only in the treetops. So what's aesthetically pleasing to many of us is also what creates the most hospitable environment for animals. (Personally, I don't think that's the least bit accidental.)

It's important to keep structure in mind when planning a landscape. Trees provide that essential top layer of landscape structure (even aside from all the other benefits they convey). Since trees take a long time to grow, we always want to hold onto and take advantage of any trees already present on the site, creating a design around them. If there are no trees on the site yet, we'll want to decide what we want in that top layer and get that planted before starting to worry about anything else.

While waiting for big trees to mature, consider planting fast-growing trees such as paper birch. Typically trees that grow quickly don't live long ("live fast, die young"), but some clumps of short-lived, fast-growing trees will give at least the illusion of an upper level while the slower growing, long-lived trees plod along to their ultimate size. In the meantime, those fast-living trees provide shelter for wildflowers and animals. And when they do die, they become excellent habitat for birds and other animals that nest in decaying trees.

This homeowoner created structure in a relatively new garden by planting fast-growing paper birch in a key location. Even though they probably won't live long, fast-growing trees create wildlife habitat and the shady conditions needed by many wildflowers that are native to wooded areas.

Sometimes you can get the effect of a canopy layer using man-made structures, especially if you grow vines on them. Some structures such as houses or pergolas can be covered in perennial vines. But you can also use fast-growing annual vines such as scarlet runner beans to mask structures such as telephone poles that wouldn't be suitable for permanent plantings. (Sure, there's a chance you'll lose the vines if the telephone company needs the pole, so that's why you want to plant easy annuals such as scarlet runners. But more likely the phone company will find other things to do, and you and the hummingbirds will get to enjoy the flowers.)

Whether you're gardening for wildlife or gardening for yourself, your environment will be richer and more aesthetically pleasing if you remember to plant the bones.

In this painting by Monet, layers come from low-growing flowering plants, flowering plants that have been raised above the ground in pots and window boxes, a small tree and large shrub, and -- at the top level -- vines that have been trained to grow to the roof of a two-story house. Both Monet paintings, the Van Gogh painting, and the Art Nouveau woman in the background of the image at the top of this post are all courtesy of Dover Publications.

The Forest (or Woodland) Garden

This photo shows a scene from a woodland garden in the Pacific Northwest. Beyond the fence is a completely developed area, with nothing but pavement for miles around. Within the fence is a serene haven for humans and birds. The photo illustrates one of the key principles of woodland gardening, which is the use of vegetation at multiple levels rather than (as in a traditional flower garden) just near the ground. Douglas fir trees provide the top layer. The intermediate layer is occupied by a PNW native shrub called osoberry, and the ground layer is covered with a glossy-leaved native called Oregon grape.

FOREST OR PRAIRIE? Most gardeners are Prairie gardeners, in a sense. Because we like flowers, we tend to like sun. That in turn leads us to prefer gardens that are open and treeless, mimicking the conditions in the wide open Prairies of the Midwestern provinces and states. Many of the most popular garden plants--purple coneflower and black-eyed Susan to name just two--came to the garden from the Midwestern Prairies.

I grow Prairie plants myself, because in addition to being beautiful and hardy, they also attract pollinators. However, for the last 14 years of my gardening life (since leaving Illinois in 1993), I have lived outside of the Prairie States. First in the Seattle area and now in Nova Scotia, I have lived in areas that are naturally forested. And it has always seemed "just natural" to me that my gardens in these areas should be forested too. When the existing tree cover wasn't adequate, I've planted fast-growing trees and planted large shrubs in order to try to get a woodland effect, as I described in a post called "A Walk on the Shady Side".

I have come to prefer this style of gardening to the open style. You don't get as many brilliant flowers in shade, but woodland gardens are cool, quiet, and serene; they are great habitat for birds, and they are relatively easy to maintain. I've also come to appreciate the aesthetics of a shady garden: Because you can't lean on flashy flowers for effect, you have to pay a lot more attention to foliage, structure, and other subtle ways of creating beauty.

Until today, I never gave a lot of thought to where woodland gardening came from, however. So I was very pleased to read an article in today's Guardian that provided some background on this topic. Jill Tunstall writes in the British newspaper that this style of gardening "goes back to the Aztecs but was reinterpreted by the late Robert Hart, a visionary gardener who brought the idea to Britain in the 1960s and named it 'forest gardening'."

She says that Hart, who lived on the border between Shropshire and Wales, realized that forest gardens "were both productive and self-maintaining. He set about rearranging his own garden on forest principles with edible layers of self-sustaining perennials that would provide food, fuel and medicines, as well as support wildlife. His philosophy was recorded in two books, The Forest Garden and Beyond the Forest Garden (Green Books), both published shortly before he died in 2000."

Tunstall insterviews garden designer Jennifer Laurol, who emphasizes, quite correctly, that the key structural element of a woodland garden is layering--that is, the use of vegetation on mutiple levels. Books on natural design typically describe three layers, which roughly correspond to trees (top level), shrubs (intermediate level), and groundcovers (ground level). But apparently Robert Hart listed seven layers, from roots all the way up to the high canopy.

There does seem to be a key difference between the British forest garden and what designers here in North America are more likely to call a woodland garden. (See for example Rick Darke's book The American Woodland Garden: Capturing the Spirit of the Deciduous Forest, published in 2002.) Designers here tend to want to imitate the ecosystem that would occur naturally on a site, which requires using native plants or at least trying to. In contrast, British designers seem to be more interested in growing food than in imitating the local ecosystem. Hart seems to have emphasized that a forest garden is a more wildlife-friendly, low-maintenance way of growing food plants. I was quite surprised to learn that woodland gardens can be used to grow food plants, as a matter of fact. Although I remain committed to working with native plants, now I'm wondering whether a portion of the food garden couldn't be a lot shadier than I had previously planned.

One thing is certain: Even if you're not a native plant enthusiast, as I am, if you live in a naturally forested area the woodland or forest approach to design is more appropriate, better for wildlife, and easier to maintain.

Many thanks to the member of the Native Gardening group on Yahoo! Groups who tipped me off to the article in the Guardian.