Orchidaceae is one of the largest and one of the most complex families of flowering plants in the world. There are nearly 30,000 species of orchids in nature (with more still being discovered), and well over 100,000 hybrids which vary in size, shape and colour. They can be found in almost any part of the world with the exception of the frozen and arid regions.
Orchids are noted for their dramatic flowers, which have evolved because orchids are highly dependent on having a pollinator to work for them. They have developed flowers specifically designed to trick a particular insect, bird or even mammal to collect pollen from one orchid and carry it to another.
Orchids have four main growth habits, examples of which are found in the Gardens:
Aerial rooted plants, that grow on other plants and depend on them for support but not food. Epiphytes get moisture and nutrients from the air or from small pools of water that collect on the host plant. These are most common in tropical and sub-tropical regions.
Grow on or among rocks or cliffs. These plants feed off nutrients from rain water and nearby decaying plants, including their own dead tissue.
Plants that naturally grow in the ground. Ground orchids have an underground root system of either tubers or rhizomes.
Have no leaves and do not produce chlorophyll. They are generally terrestrial - two species in Australia grow completely underground, not even appearing in the open to flower.
The Tropical Orchid House is a north-facing building designed with special thermal properties and light conditions to protect and display a vast collection of orchid species from around the world. The tropical orchid collection and tropical orchid house were donated by a long-serving Gardens volunteer and orchid collector, Noel Winney.
On entering, in the centre garden, you will be greeted by one of the magnificent Angraecum species from Madagascar, Angraecum eburneum v. superbum. Its white flowers start to appear in late autumn. On ground level are: Phragmipedium schroederae (May/June), Arpophyllum giganteum, Dendrobium species (Pike) (May flowering), Vanda, Proiphys amboinensis (lily), Phaius, Schomburgkia tibicinis. On the metal tree there are hanging a variety of orchids including hard cane Dendrobiums (May/June), Oncidiums, and Vandas. Climbing the trunk of the tree is the red flowering Hoya macgillivrayi, a species from Queensland.
A very wide range of orchid genera are represented on the shelving around the orchid house including Phalaenopsis, Dendrobiums, Oncidiums, Cymbidiums, Vandas and Cattleyas.
Interpretive signs in the entry to the orchid house provide more detailed information about the species on display.
The Temperate Orchid House contains a variety of Australian and exotic orchids, both epiphytic and terrestrial, displayed in a landscape setting. At any time of the year you can expect to find at least some orchids in flower in the Temperate Orchid House.
The entrance displays a variety of ferns and Hoya (including the white flowering variety). Walking further in, on the left, are large specimens of the Australian Phaius tankervilleae, Thunia marshalliana, the deciduous Australian Pterostylis, summer flowering Calanthe triplicata, Vandas, Coelogne species, Australian and Asian Dendrobiums and hybrids. At the back of the House are suspended baskets containing Stanhopeas (summer), the interesting genus where flowers appear below their baskets. Also suspended are various Dendrobiums and a Pitcher plant, Dionaea sp. On the shelving either side of the House is displayed various species and hybrids including Cymbidiums, Dendrobiums, Oncidiums and Brassias. Around the pond is planted a Laelia grandis, together with Oncidiums and ferns. On the right hand side in the ground is the deciduous Chinese orchid Bletilla striata which flowers in spring and summer.
Surrounding the Temperate Orchid House are Bromeliads, Australian Dendrobiums and a wall of various coloured Epidendrums. Between the two orchid houses there is an outdoor orchid garden where various species have been planted in the ground, on trees, in tree stumps and on rocks. Orchids can also be found in various parts of the Gardens in trees, on rocks and in garden beds.
• There is always something in flower in the Orchid Houses. The peak flowering period in the Tropical Orchid House is in autumn and early winter, while the Temperate Orchid House has its peak in spring and summer.
For the Home Gardener
• Various types of orchids have quite specific growing requirements in terms of light, warmth, water and soils. Once these requirements are met, many orchids are hardy plants which are quite easy to care for.
• Orchids must be given ample air and light, often in a north-facing position with morning sun. Orchids grown under dark stuffy conditions will be weak and lack the strength to fight disease or will be unable to produce quality flowers. Move pots around if not getting good results. Shifting or raising the plant can result in a temperature difference, more shade or light, more or less circulating air, or more or less humidity.
• Orchids need plenty of water while growing – at least once a week in summer, once every two weeks in autumn, then next to no water during winter while the orchids are dormant. Drainage must be perfect for orchids at all times. Use a compost that allows water to pass through quickly.
• Fertilise orchids with a weak nutrient solution frequently during the growing season.