Cymbidiums have been making a much-deserved comeback in recent years as more people discover these wonderful orchids. They are much more cold-tolerant than many common species of orchids and feature sprays of large blooms in the dead of winter. Much of the new interest in cymbidiums is driven by the appearance of the miniature cymbidiums. These plants are smaller and more manageable than the earlier varieties.
During the growing season, cymbidiums appreciate dappled sunlight, or about 50 percent shade. They can be moved outdoors in the summer, providing they are not put into direct sunlight. A few hours of weak morning sunlight and shady afternoons is perfect. Move the cymbidiums outside after the threat of frost has passed. If you're growing them indoors, a southeast or east window is perfect. Your leaves should be apple green, as opposed to dark green. A dark green plant is likely not receiving enough sunlight to provoke a good bloom.
Copious water during the growing season (spring, summer and fall). The purer the water, the better the plants. Accumulated salts in tap water can damage the plants, so make sure they are well flushed every time you water the plant. During the winter bloom, reduce watering dramatically, but don't let the plant dry out. Keep the potting media slightly damp to the finger. Plants that are affected by the salt build-up in tap water will exhibit leaf-tip dieback, a condition in which the leaf tips turn black and die.
During the growing season, feed with a weak orchid fertilizer bimonthly or scatter slow-release pellets in the growing media at the beginning of the season. Be careful to avoid a high nitrogen fertilizer as this will cause rapid foliage growth at the expense of the bloom.
Cymbidiums are considerably more cold tolerant than some other popular orchids. The large, older cymbidiums need an extended period of cold to provoke a bloom, while the miniatures aren't quite as dependent on cold weather to bloom. Cymbidiums have been known to briefly withstand freezing temperatures, although frost will kill them. Nights down to 40ºF are fine. On the other side, cymbidiums can also withstand considerably summer heat without wilting, as they are suited to the temperate regions of Asia where there is considerable variation in seasonal and day/night temperatures.
The cymbidium bloom is triggered by a combination of falling temperatures and reduced water. The miniatures have generally been crossed with warm-house orchids, so they aren't quite as dependent on cold weather to bloom, but it's still an important part of cymbidium culture. The natural bloom season is during the winter, when your plants should be indoors and available for display. Cymbidium flowers grow in sprays, with spikes arising from new pseudobulbs every season.
Potting and repotting:
Cymbidiums are semi-terrestrial orchids. They naturally grown in loamy humus, sending thin roots into the mixture. Thus, they are perfectly suited to the conditions most easily provided at home: a rich, loose, organic potting mixture. Most growers recommend using fir bark, perlite, peat moss, and other loose organic material in some combination. A commercial paphiopedilum mix will usually serve these plants well. Cymbidiums can be easily divided during repotting in the spring.
Cymbidiums are wonderful orchids to grow in the middle and coastal regions of the United States and other temperate countries. They can be grown outside during the spring, summer and fall, and moved back inside at the first threat of frost. During the summer, they will grow quickly, sending up new pseudobulbs topped with long, strappy leaves. The flowers are on display during the winter months. A well-grown cymbidium is resistant to most insects, but as with all orchids, there is some risk of aphids, scale and other insects. Treat with standard products, always following label directions.