Plant Selection (I)

Functions of plant materials in your garden

Proper plant selection is very important for the creation of a successful garden.  Plants perform numerous aesthetic, spatial, and climatic functions in the garden.  Understanding these functions will allow you to make the plant choices most suitable for your needs.

The visual principles of color, texture, scale, and rhythm can be used to create an aesthetically pleasing planting environment.  Plants can serve to unify other design elements, provide neutral backgrounds for focal points, relate a structure to its surrounding site, and reduce the ‘hardness’ of the adjacent or surrounding architecture. Moreover, special plants of high visual interest, such as specimen trees, can be used to dramatize certain views.  A specimen tree is one with particularly impressive characteristics embodied in its flowers, leaf texture, or form.  Specimen trees can be planted alone or in groups, usually in the most important areas of the garden, and generally are installed as mature plants, when their true form and unique, individual character has begun to emerge.  However, it should be kept in mind that specimen plants tend to be more expensive than plant materials used en masse.

Plants also can help influence the microclimate of an outdoor space.  Creating pleasant microclimates is possible through the careful placement of trees and shrubs so as to block excessive sun or wind. Trees with dense canopies can produce dense shade but may restrict what you can grow under them.  On the other hand, trees with filtered shade provide protection from the sun and also allow undergrowth.  If intended as windbreaks, plants should be planted perpendicularly to the prevailing winds, and should consist of several rows of different plant types (e.g. one row of trees, one row of shrubs, one row of smaller shrubs…) to minimize wind infiltration.

Screening is another function plants can perform in your garden.  Plants that act as visual screens can range from semi-transparent to uninviting thorny hedges.  Such screens can be used to provide privacy, mark boundaries, discourage intruders, or block unpleasant views.  Screen plants should be dense and tall enough to provide a visual barrier.

Plants can act as space defining elements in the landscape, and can serve the same functions that many “hard” building materials serve: to form outdoor walls, fences, and canopies that define spaces or circulation routes.  Although they require more space than hard building materials, plants typically are less expensive to buy and install, and require little maintenance if properly chosen.  Dense and low growing plants can act as ground covers, and plants with adequately dense leaves, which are tall enough to walk under, can be used to create a canopy that defines an overhead space.  Using deciduous vines for overhead trellises provides shade in the summer but allows the winter sun to enter.

Plants also can attract birds, butterflies, or other forms of wildlife for human enjoyment.  Conspicuous fruits, both fleshy and dry, attract birds, and showy, nectar-bearing flowers may attract hummingbirds and butterflies.

Plants also serve as an element of environmental stabilization.  They can stabilize eroded slopes and revitalize damaged soils.  When using plants to prevent water [you mean “soil”] erosion, such as on a slope, use plants with fibrous roots, and low-growing plants with dense foliage that is close to the ground.

As you begin to select and introduce the plants into your landscape, take care to situate them where they can most effectively perform their intended functions.  

The upcoming article of this series will discuss appropriate plant selection techniques for your landscape.