Density and Diversity: Parts of Australia in company with South Africa have been called the “Shrubberies of the World”. Eastern Australia and the Southwest corner of Western Australia bulge at the seams with a fascinating range of native shrubs. These areas of botanical and horticultural interest have two things in common. A high density of plants in each square metre and this concentration of plants frequently contain a diversity of species. Over the years we have attempted to duplicate nature in our horticultural endeavours. The gardens at Yallaroo have high density and lots of diversity. High density allows plants to support and protect each other. This is important in our harsh climate. Species diversity means that we are not putting all our “horticultural eggs” in one basket. If one variety fails there are others to fill in the gaps. Because we are constantly trialling new species and varieties there is always the chance of a few failures. At Yallaroo we now place two plants in the one hole and work on a minimum density of three plants per square metre. This extravagance of planting is possible because the majority of plants are propagated on site.
Two other points to consider: Dense and varied planting will create shelter and nesting sites for small native birds. We have reached the stage when all gardeners should consider the environmental consequences of their horticultural activities. Also cultivating a wide range of natives will add interest to your domestic surroundings with a range of foliage and flowers.