Dendrobium speciosum is one of the world's most underrated and exciting of orchids. They are capable of producing possibly the largest display plants and most spectacular shows of mass blooming of any known orchid. Extraordinarily tough, hardy and drought tolerant it should be one of the most cultivated plants ever! It can tolerate near frost to temperatures over 45°c without severe damage.

This orchid is native to a vast section of Australia ranging from Mallacoota (37°33'S) in South-East Victoria to the tropical conditions up past Cairns (16°57′S). Because it is found over such a vast region, botanists have broken the species apart into many subspecies or varieties. It seems every few years they change names again, so we will mainly use the oldest and most accepted names in this guide.

In almost every occasion I have seen this orchid in the wild, it is growing on granite cliff faces or boulders in open grassy paddocks. The photo below shows just how open bright and exposed these magnificent orchids require. They are huge growers, so in time they may require a giant tub or preferment position in the garden.

Source: https://www.australianorchids.com.au/pages/dendrobium-speciosum-the-sydney-rock-orchid