Pronounced: [ On – sid – ee – um ]
WHERE DO THEY COME FROM
This large group of evergreen orchids come from Central and South America. They are epiphytes or lithophytes and most occur at high altitudes. They grow from pseudobulbs from which one to four leaves emerge. Flower spikes are very variable and may be tall or short, upright or arching in habit but all originate from the base of the pseudobulb. Many species are grown but it is the hybrids that are widely cultivated. The hybrids occur in almost every colour of the rainbow and are marked in an extraordinary range of patterns.
Climate Needs a frost-free, but generally not a hot tropical climate. They prefer a temperature range from 10C. to 25C. High humidity is essential for these orchids.
Aspect Needs shade, especially in summer when 70% shade cloth should be used. This can be reduced to about 50% shading in winter.
Potting Mix Needs very open and free draining pine bark based mix. You can add coarse gravel, charcoal or granulated isolite if you so wish. You can also grow in total sphagnum moss. Don’t over-pot. Use pots just large enough to confine the roots.
Propagation Divide plants after flowering when the new growth is showing sign of active root movement. Don’t over pot your divisions.
Watering Never allow plants to become bone dry, but the roots should never be sodden. Frequency of watering depends on the mix used and the weather. Do not water your plants in the hottest part of the day in summer. Early morning or in the evening is best and water the ground of your growing area during hot days to keep the humidity high.
Fertilizing Use a soluble well balanced liquid plant food at half strength every couple of weeks through the warmer months. Don’t over-fertilize if plants are in sphagnum moss as this will sour the moss.
Problems The main pests with these orchids are aphids when the flower buds are forming and when flowering. Gentle hosing of the blooms will remove the pests or use a spray from a distance. . Do watch out for scale and treat with White Oil where necessary.
Flowering The flowering season is very variable, depending on the species or hybrid.