The Australian Rhododendron Society was formed in Victoria in 1960. Today there are Branches in South Australia, New South Wales, Southern Tasmania and North West Tasmania.

The Society’s Victorian Branch was responsible for establishing and planting out the National Rhododendron Gardens at Olinda, on Mount Dandenong, starting in 1960, on a site which was made available for this purpose by the State Government of the day. The North West Tasmania and Illawarra Branches (the latter now a separate organisation) also established large gardens, planted extensively with plants of the rhododendron family.

In 1968 the search for a suitable site in the Illawarra revealed a quiet valley, 229 to 274 metres above sea level at Mt. Pleasant under the north eastern summit of Mt. Keira. This land was owned by Australian Iron and Steel and the then General Manager, Mr A. A. Parrish backed the scheme.  A (peppercorn) lease over six hectares (14 acres) was granted to the Society to set up, develop and manage the garden.

The garden contains thousands of azaleas and hundreds of rhododendrons in company with many rare companion plants.  Plantings include large numbers of Vireya rhododendrons and hybrids of Australian origin.  A section of rich rainforest is featured in the top section with walking trails.

The Illawarra Rhododendron Gardens is not funded by government or council.  It is managed by a group of volunteers and all funds received, such as booking and parking fees and donations, are used for the maintenance and upkeep of the park.