There is No Design without It
Establish boundaries and the outline of your design by defining the edges of the elements with which it is composed. There is no place for wimpy gestures in professional landscape design!
Make a clean line on the ground plane using edging, different materials, or changes in height and color.
Create a silhouette on the horizon and frame important structural elements.
Control the eye by defining the path it should follow toward a dramatic focal point.
Landscape design should not only be deliberate (form follows function), it should appear very deliberate. Define the forms with strong visual edges and lines.