In nature, edges provide rich habitats as well as eye-catching scenery. These boundaries between different types of physical environments [that I have come to call "habitats"] provide unique conditions which plants and animals are quick to exploit. In B.C., of course, the finest examples of this are the incredibly rich inter-tidal 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 usually less extensive and sometimes more subtle, but potentially every bit as important and interesting. Man-made edges already 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 micro-climates they provide, are usually the inadvertent result of the functional spaces we create, and can be over-looked in terms of the planting opportunities they provide. We have a tendency to pay more attention to the flower bed in the middle of the lawn than the interface between lawn and front porch, or back lawn and fence. The interesting question don’t get asked – do we want to hide these interfaces or emphasize them? What is unique about this space, in terms of soil, drainage or sunlight, colour or texture of the backdrop, or contrast between two surfaces?
If we look more closely at the spaces we create, and the edges they create, we may also discover that growing conditions can vary from place to place in the garden more than we think. The mystery of why one variety of plant thrives in this particular spot, but it’s genetic twin sulks and then dies three feet over, in 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 with any variety of plant can be affected by something as simple as a large rock or small shrub sheltering a small alpine plant. In my fairly open and exposed Zone 3 garden near Prince George, B.C., various lungworts (Pulmonaria species and cultivars) thrive in the shelter of large deciduous shrubs such as Lonicera caerulea (Honeyberry) and Viburnum opulus (Highbush cranberry).
They bloom in the spring before the shrubs leaf out fully, and then disappear under the shrub foliage as summer progresses. For years I made mental notes to move them out into ‘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, it also thrives in a sheltered location and the dappled light which highlights its silver leaves. At the northern end of its range, this one seems to appreciate the tradeoff 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 improving the soil and contemplating the benefits vs costs of drip irrigation.
Habitats in the garden:
Becoming more aware of the edges in my garden is making me think more about how and why plants thrive, or fail to, and in the process making this garden more visually interesting, lower-maintenance, and more environmentally friendly. 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.
This article originally appeared, in a slightly modified form, in the Early Summer 2006 issue of GardenWise Magazine.
BR, March 2012.