Most garden planting design is on land which, if cleared of vegetation and then vacated by man, would pass through the following ecological succession which correspond to the four primary categories of garden planting:
But the four categories of planting can be combined in many different ways to create a design- see our brief summary of the history of planting design. Gardeners affect the ecological succession, by planting and maintenance operations, for a variety of reasons:
Perennial herbs
Annual herbs
Woody shrubs
Woodland trees