Plants are the major element used to define the boundaries of outdoor space just as walls, ceilings, and floors are the elements that define space indoors. In planting design, shrubs become walls, groundcovers, turf grass, and hardscapes become floors, tree trunks become columns, and tree canopies become ceilings. These are referred to as the ground plane, the vertical plane, and the overhead plane.
You can create spaces with any one of these planes alone, or create rich layered spaces through the combined effect of all three. For instance:
- 1 tree can be a column to lean against, an overhead canopy that provides shelter and creates shade, and a marker for a place on the ground plane through its shadow.
- Different patterns of groundcovers, turf grass, and hardscapes can create spaces just like rugs, carpet, tile, and hardwood can be used indoors.
- A row of shrubs can create a wall that separates one space from another.
- A 3 foot tall shrub creates a physical barrier (you can see into the space but can’t physically walk into it) and an 8 foot tall shrub creates a physical and visual barrier (you can’t see into the adjoining space).
- Trees of different heights can create a vaulted ceiling affect and spaces between them can act as skylights.
Planting design becomes much stronger when thought of in these 3 dimensional terms. All of these elements should be combined to create a space that you want to be in, rather than an object that you want to look at.
~Trey McBride, BLA