Edge Gardening

Credit: Barbara Rayment

Edge Gardens Pulmonaria

Edge Gardens Pulmonaria

In nature, edges provide rich habitats as well as eye-catching scenery. These boundaries between different types of environments provide unique conditions that plants and animals are quick to exploit. In B.C. the finest examples of this are the incredibly rich intertidal zones of our coastal beaches; I have many fond childhood memories of summer afternoons flipping barnacle-encrusted rocks, poking under driftwood logs and hanging over the edges of docks to catch a glimpse of an alien and beautiful world.

In the garden, our man-made edges are less extensive and sometimes more subtle, but potentially every bit as interesting. They exist along buildings and fences, beside paths, driveways and hedges, at the verges of small ponds or bog gardens, and even in the lee of large shrubs and under trees. These edges, and the microclimates they provide, are usually the inadvertent result of the functional spaces we create. The planting opportunities they provide can easily be overlooked.

We have a tendency to focus on the spaces in our gardens to start with, rather than the edges, according to prominent Vancouver landscape architect and garden designer Ron Rule. This can be a mistake and a lost opportunity, as Rule points out (GardenWise, Early Spring 2006) because “garden design is largely an exercise in manipulating edges.” If we look more closely at the spaces we make and the edges they create, we may also discover that growing conditions can vary more than we think from place to place in the garden.

The mystery of why one plant thrives in a particular spot, but its genetic twin sulks and then dies a few feet over, is usually solved by a closer look at what is happening down at plant level. The harsher the climate we garden in, the more important these microclimates can be. Success can be affected by something as simple as a large rock or small shrub sheltering an alpine plant.

In my fairly open and exposed zone-3 garden, various Pulmonaria species and cultivars thrive in the shelter of large deciduous shrubs such as Lonicera caerulea edule (honeyberry) and Viburnum opulus (highbush cranberry). They bloom in spring before the shrubs are fully leafed out and then disappear under the foliage as summer progresses. For years I made mental notes to move them to better locations, until it finally occurred to me that they were perfectly happy, and the protected shade in the summer months was exactly what they wanted. (Procrastination can be as useful as observation.)

Elaeagnus commutata (wolf-willow) is native to the hotter, dryer climate of the southern interior, and is usually found in full sun there. Here in the north, it thrives in dappled light, which highlights its silver leaves. At the northern end of its range, this one seems to appreciate the trade-off between sun and shelter and has adapted with surprisingly compact growth, creating a pleasing vignette.

Hardy geranium species, some of which can grow and self-seed a little too vigorously in the open garden, have become a well-behaved and low-maintenance groundcover in the dry river rock under the house eaves. This particular “edge” is a common problem spot for gardeners, and I was glad to see that the plants found the solution for themselves while I was busy debating how to improve the soil and contemplating the benefits versus costs of drip irrigation.

Becoming more aware of the edges in my garden is making me think further about how and why plants thrive, or fail to. This acre of plant habitat is actually a thousand small habitats, and my development as a gardener and garden designer is tied to my growth as an ecologist and observer in this place.

Barbara Rayment operates Birch Creek Nursery, in Prince George, where she grows and experiments with a wide variety of hardy plants.