Landscape Design: Role of Plants

Selecting plants for successful garden landscape designs is more or less like planning a party. Plants function in good garden landscapes much as guests interact at a successful party. A good blend of guests is as important as an appropriate setting; suitable plant combinations function in proper site conditions. Careful plant selection for desired characteristics allows plant choices to function admirably in specific roles.

Knowing the mature heights and widths of plants you intend to use is crucial. Similarly, overall shape, texture, and form are qualities that bring diversity and interest to a design. Research mature qualities of desired trees and shrubs in tree books and garden design encyclopedias.

• Plant Height and Width

Beware of preconceived notions, advertising expressions, and appealing plants when selecting landscape plants. A common example of where designs can get off track is choosing, without research, miniature or dwarf plants for a design. More often than not, miniature and dwarf cultivars (cultivated varieties of plants) are only as small as the relative to which they compare. Here are two familiar and often-used dwarf woody ornamentals that grow quicker, taller, and wider than commonly expected:

1. Dwarf Alberta spruce (Picea glauca variety albertiana ‘Conica’) grows about 1.5 – 2-inches per year but matures and loses its neat conical shape at 6-feet-tall. Its normal relative Picea glauca reaches about 24 feet in 15 years.
2. Dwarf euonymus (Euonymus alata ‘Compacta’) is slow growing and compact, but matures as an open shrub at 6-feet or taller. Its typical Euonymus relative can easily grow to nine feet in 15 years.

Maximum and beneficial spacing means little or no future transplanting or loss of mature trees and shrubs. A case in point: The lifespan of most commercially planted residential landscapes, especially in new developments, is approximately ten years. Why? Because homeowners want to see an immediate finished design. After ten years, a new landscape is installed because plants are too big and crowded.

• Visual Interactions

Various heights, widths, forms, and textures build and shape landscape designs. Plants within a composition must also relate to buildings and other structures present. Common composition problems appear when too many plants alike in shape and texture are used. Disregard for existing buildings also becomes a dilemma. What are some of these problems?

1. A repetitious and boring landscape. Too many plants are of the same size, shape, and texture such as broad-leaved evergreen shrubs and needle-leaf evergreen trees.
2. Security hazards and visual obstacles. Broad-leaved shrubs and needle-leaved trees grow past window ledges and reach to second story windows.

• Composition Success

A universal inclination among landscape gardeners is the impulse purchase. Avoid acquiring plants because one or two traits are appealing. It takes will power to walk past a plant that seems to be begging for a home.

The question to keep uppermost in mind is: “Will those plants work well within my planned design?” Many times a plant, such as a weeping Higan cherry tree (Prunus subhirtella ‘Pendula’), works within a design, but not necessarily well. When the weeping Higan cherry blooms in early to mid-spring, nothing can match it for grace and beauty. On the other hand, it may not be the best to fit the role that the design location needs for the rest of the year.

Landscape Design: Plant Selection, A Key Factor – Knowing Site Conditions (number one in this series), this article (number two), and those following are planned so the five Plant Design Factors and their Divisions form an outline that can be printed and used as a checklist during your landscape design process and plant selection.

©Text and photograph by Georgene A. Bramlage. February 2007.Reproduction without permission prohibited.