Designing your garden may be easier if you think of it as building an outdoor room. Instead of using construction materials, you use plants to create the framework — the floor, the ceiling, and the walls — of your outdoor room. The floor can consist of a lawn, ground covers, and sprawling vines. High-branching trees and vines trained on overhead structures can serve as the ceiling. Outdoor walls can be formed from shrubs, hedges, trees, and vine-covered fences and trellises.
Once the floor, ceiling, and walls are in place, you use other plantings — such as flower beds and specimen plants — to accent the basic framework.
Plants used as accents should be selected for their fine or unusual features. Often they look best when planted together, either in small groups or in masses. Some accents, especially large ones, are best planted alone; when using an accent alone, place it in a location where it will command center stage, and emphasize it by surrounding it with simpler plants.