Many groundcovers are prostrate perennials that form either a mat or multiple clumps, spreading by means of above-ground stolons or underground rhizomes. Some prostrate shrubs are also classed as groundcovers, and some climbers will grow vigorously across the ground if there is no vertical support for them to grow up.
Anticipating the spread
When buying a groundcover, read the label and take note of the height and width that it is expected to reach — then be prepared for it to exceed those dimensions, especially in optimum conditions. Be wary if the label describes a species as having “indefinite” spread. Avoid accepting cuttings from friends or neighbours who say that this particular plant gives rapid coverage. Do not order seeds from overseas, or seeds and plants from interstate, or the internet, as you might inadvertently bring in a weedy species that could pollute natural habitats in Western Australia.