by Edwin Oka
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Oncidium orchids are called dancing girl because of the flower shape and the way they move in the slightest breeze. The flowers vary from tiny to 3 or 4 inches across, blooming in quantity on long, gracefully arching stems. Variegata and equitant types have fans of short leaves 1 to 4 inches long and spikes of small flowers in pink, brown, white, or yellow. They grow well on cork-bark slabs or attached to a bromeliad tree.
Ideal light is a sunny east or west window, or near a sunny south window. Miniatures grow well in a fluorescent-light garden.
Temperature & Humidity — Average house temperature in winter. Orchids suffer in dry heat. Provide humidity in fresh air that circulates freely. A minimum of 65 degrees at night and the ideal day of 75 degrees. Cooler night-time temperatures help to initiate buds and promote strong growth. Ideal humidity is 40-45 degrees. To raise humidity, use a humidifier or place pots on a layer of gravel in a tray, without letting the pot sit in the water.
Potting — Osmunda fiber, redwood bark, shredded fir bark, or chunks of tree-fern bark. All are available from orchid specialists. Repot biannually, after blooming (in larger pot if needed), using an orchid mix. Cut off inactive roots and plant in center of pot. It is normal for roots to grow over the side of the pot.
Clay pots with side openings are for perfect drainage; or standard plastic or clay pot if careful not to over water.
Watering — Water thoroughly when media is almost dry to the touch. Drench growing medium and then allow it to dry between waterings. This will vary according to the season. Water from the top with lukewarm water and avoid getting water in the crown. Do not leave pot standing in water. Mist often.
Feeding — Feed alternately all year with all-purpose and blooming type plant foods, follow container directions for frequency. Use a 30-10-10 fertilizer twice a month at half strength. For larger blooms switch to a 10-30-20 when plant is in bud.
Problems — Insufficient light and dry, stale air prevent flowering.
Propagation — Plant root divisions, following the flowering season.
How often orchids bloom depend on the variety plus factors of culture and care. Blooms of hybrids of the Cattleya family may last up to four weeks on the plant. Those of the Phalaenopsis family commonly last from one to four months. Large plants of Phalaenopsis will rebloom on a secondary spike, if the active spike is broken just below the first flower. The most popular orchid types bloom in winter and spring, but orchids may be found that bloom in any month of the year. Most orchids are very long-lived. In fact, some species are virtually immortal, given the proper attention. Divisions or propagations of orchids discovered in the 19th century are still growing and blooming today … a botanical heritage from an earlier century.
Oncidium culture article by Edwin Oka from Na Okika 2005, slightly revised.