Coelogyne is a plant genus that belongs to the Orchidaceae plant family. It consists of about 140 species of orchids that are native to countries of southeast Asia, including India, southwest China, the Philippines, and Indonesia. Most of these species are tropical plants, while a select few are acclimated to the cold climates of the Himalayan region. Some common species within the coelogyne genus are C. cristata, C. mossiae, and C. mooreana.
The climate in which coelogyne orchids grow is dramatically different during the winter and summer months. Typically, high humidity and torrential downpours mark the monsoon season, with dryer conditions returning by winter. To replicate the natural conditions that coelogyne orchids are accustomed to, it is usually recommended that a gardener match the watering schedule to the growth cycle. During the growing period, the coelogyne generally requires frequent watering but as it matures in the fall, the amount of water should be gradually reduced. By winter, only an occasional morning mist should be applied to the orchid; as new roots grow in the spring, the amount of water should be increased.
Keeping the orchid adequately hydrated is a concern when deciding the type of growing medium to use. Generally, a shallow pot or basket filled with a mixture of tree-fern fiber, charcoal, perlite, and sphagnum moss delivers a well-draining medium that does not dry from watering to watering. A balanced fertilizer is generally added to the medium once a week during the growing period. To avoid the buildup of salt that may result from the fertilizer and mineralized water, the medium is generally leached every few weeks.
Excess salt buildup may cause the tips of the coelogyne orchid to die-back. Another possible cause of tip die-back is root rot, which is a degradation of the root tips, usually caused by over-watering. This prevents the roots from absorbing enough nutrients from the medium.
To determine the cause of tip die-back, an examination of the roots is generally required. Soft, brown roots that fall apart during removal are rotted. This typically requires re-potting. If the roots are fine, then excess salt is usually the reason for tip die-back, and leaching is required to correct the problem.
An orchid could outgrow its pot or basket, thus requiring pruning or re-potting. Re-potting can be risky, since orchids may not grow accustomed to a new setting. To increase the chance of survival, it is generally recommended that a gardener replant the orchid when new roots are emerging.