Human awareness of plants in Australia goes back 50,000 years when the aboriginal first began using plants to treat, clothe and feed themselves. The European influence came in 1778 with the First Fleet landing in New South Wales. Australia's earliest records of using horticulture for therapy and rehabilitation were in institutions for people with intellectual disabilities or who were incarcerated. Eventually, legislation created greater awareness in the government and community for the needs of persons with disabilities, and many worthwhile projects, programs and organizations were established or gained greater recognition. Horticultural therapy programs may be found in nursing homes, rehabilitation centers, adult training support services, hospitals, day centers, community centers and gardens, educational institutions, supported employment, and the prisons system. This article reviews the history and development of Australian horticulture as a therapy in the treatment of disabilities and social disadvantaged groups, and includes an overview of programs offered for special populations and of Australia's horticultural therapy associations. It also discusses opportunities for research, teaching and extension for horticultural therapy in Australia.