Orchids are amongst the most widespread and highly evolved of plant species. There are thought to be over 20,000 naturally occurring species, and many hundreds of thousands of man-made hybrids. Although they are considered to be exotic and delicate, many orchids are surprisingly easy to grow in cultivation, once you understand their unique needs. Orchids have unsual root structures which need to be in contact with the air, and most cannot be grown in the type of soil used for common house plants. The preferred medium is bark or tree fern.
There are hundreds of orchid genera, but the ones which are easy to grow in the home and most likely to be found in nurseries or garden centres or florists are:
Cymbidium (boat orchid)
Cymbidiums originate from Asia - growing in cool regions ranging from northern India through to Vietnam and China. They are terrestrial orchids and the plants consist of long strap-like leaves which grow on strong psuedobulbs. The overall height of the plants can range from 1 foot to 4 feet tall. Cymbidiums tend to flower between the autumn and the spring. They require a cool period at the end of summer to initiate flower spike production so are not suitable for growing in warm climates. The flowers are carried on a strong spike and are long lasting - a cymbidium can easily flower for 2 months or more. The species tend to have small flowers 1-2" wide, and the man-made hybrids are both larger and more colourful.
Phalaenopsis (moth orchid)
Phalaenopsis originate from the rain forests of central Asia. They are epiphytic plants and grow on tree branches in the tropical jungles. The plants consist of wide leaves which emerge alternately from a central crown. On mature plants, these leaves can grow to a length of 10 inches or more. Phalenopsis can flower at almost any time, but their peak flowering period is the spring. The flowers are carried on long arching spikes and open in a sequence. On a strong plant, a spike can flower for 3 months or more. Sometimes, the plant can re-flower on a previous year's spike. They love humid conditions and a bright bathroom makes an ideal room to grow them in. True species of phalaenopsis are hard to find these days and the vast majority of plants on sale are man-made hybrids. They are available in a remendous range of flower colours, from white through yellow and pink to red and deep magenta.
Dendrobium (cane orchid)
Dendrobiums originate from central and southern Asia. This genus contains a large and varied selection of species. Some plants are deciduous and others are evergreen.
Oncidium/Odontoglossum and related genera
These genera originate from South America.They prefer cool conditions.
Cattleya/Laelia & related genera
These genera originate from Central and South America, from Mexico through to the rain forests of Brazil. Cattleyas have been crossbred to create some of the largest flowers of the orchid world - exceptional blooms can be up to 10 inches across! Combinations of Cattleya, Laelia, Sophronitis, Brassavola and Encyclia have led to the creation of hybrids with some of the most striking and colourful flowers which one can expect to see.
Miltoniopsis (pansy orchid)
This genus originates from Central and South America. Miltonias are delicate plants, with large flat-faced flowers. Colours range from whites and yellows through to pinks and purples. Some of the flowers have an attractive waterfall or teardrop pattern. Occasionally, the flowers can be scented.
Paphiopedilum (slipper orchid)
This genus originates from Asia. The flowers are distinctive, with the dominant features being a rounded pouch (formed from 2 fused petals) and a large dorsal petal immediately above the pouch. There are also two side petals. The cooler growing types from northern Asia have plain green leaves whereas the warm growing types from tropical Asia have mottled leaves which are attractive even when the plant is not in flower. The flowering period varies depending on the origin of the plant.