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Planting in Layers

  • Barbara Euser
  • By Barbara J. Euser

    Gardens are works of art in progress: the process is never completed. Whether we are designing new sections of the garden, or making modifications as a garden matures, we have an opportunity to view the garden as a succession of layers. Layers can be either horizontal or vertical. In our three-dimensional garden spaces, we must consider both. In fact, as we make a choice in the horizontal dimension by filling a bed with plants, the vertical dimension is created by the heights of the plants we choose. As an artist layers in details to a drawing, we layer in plants of different sizes, colors and forms in our gardens.
    The first layer to be considered in the garden is the hardscaping. Hardscaping is the walls, fences, paths, stairs, and patios around which the garden grows. The space between a sidewalk and fence offers the opportunity to plant a perennial border. Walls of fences offer opportunities for vertical plants, such as vines or climbing roses.
    After the hardscaping, trees and bushes form the bones of the garden. They are the skeleton over which layers of annuals, perennials and vines will form the body.
    In a formal garden, plants are often carefully spaced in even rows, according to height, from the shortest in the front to the tallest in the back of a given space. For example, a clipped boxwood hedge in front of medium-height geraniums in front of upright Tuscan rosemary. In a formal garden, plants farther from the center may be trimmed shorter, thus creating an optical illusion of distance and a much larger garden. Formal gardens, where plants are centered and each plant is balanced perfectly by a plant on either side, create a feeling of order and stability.
    By contrast, most household gardens are informal. Rather than planting rows of plants, groups or clumps of plants are more pleasing. Layering in this case may mean putting clumps of coreopsis in front of Salvia greggii and silvery-leaved Santolina. Groups of plants should be placed off-center to create a feeling of flowing movement. Layers of plants of different heights keep the eye moving throughout the garden.
    Here are some examples of plants that can be used to create layers in the garden. A monochromatic color scheme can be created by using plants in different shades of one color, for example, purple. Low-growing lobelia could be used as the first layer, in front of Nepeta (catmint), in front of French lavender plants, in front of Mexican sage. Interspersing groups of white flowers, such as Erigeron (Santa Barbara daisy), will make colored flowers appear more brilliant.
    When I first began planting my garden about ten years ago, I chose mostly medium-height plants. That made for a boring garden. Happily, over time, I began to fill in the edges with lower-growing plants and I added taller plants as a backdrop. Although I had read about the concept of layering in gardens, I didn’t begin to really understand it until I discovered that the variety and interest created by layers were missing in my own.
    In my own garden, I use woolly thyme as a ground cover in front of a low-growing, dark purple verbena that grows beneath California poppies. Overshadowing the poppies, bronze daylilies grow in front of pink Valerian. Coyote bush and Salvia clevelandii are the anchoring bones.
    Another aspect of layering is form. Gracefully arcing leaves of daylilies contrast with the spear-like foliage of Dietes that bloom every two weeks or so, as their common name fortnight lilies implies. In one area of my garden, lavender and prostrate rosemary grow in front of a mature grevillea bush, and long stalks of salmon gladioli add colorful punctuation in between.
    As my garden has matured and changed, I take the opportunity to add or replace plants with ones that add interest and complexity to my garden in layers of size and color and form.