Coelogyne Culture: The Large-Flowered, Cool-Growing Coelogynes

Coelogyne cristata 'The Queen', AM/AOS

Coelogyne comprises about 196 species (World Checklist of Monocotyledons, 2009). Most of the species are easy to grow and produce long-lasting, fragrant flowers and should be much more popular with hobbyists, especially the large flowered cooler growing species as fuel cost rise.

Coelogyne species are distributed from India through Southeast Asia, southwest China, the Philippines and the islands of Indonesia to as far east as New Guinea and islands of the southern and eastern Pacific. Those that have particularly attracted our attention are the cool-growing species from the Himalayan region of India and Southeast Asia. The climate is such that species originating here are best grown using a program of benign neglect during winter. Heating bills are, therefore, low because these plants neither require nor want warm temperatures. In addition, their greatly reduced need for water in winter provides growers with opportunities to be away for several weeks without having to worry about care for their collections.

Basic Cultural Needs
Coelogyne cristata, Coelogyne mooreana and Coelogyne mossiae (as well as the hybrid Coelogyne Unchained Melody) are among the largest-flowered in the genus and are discussed here. We will first consider their common cultural requirements and then take a closer look at their specific needs.

Humidity should be high all year, 85% in summer to early fall, decreasing to 60-70% in early winter. The driest time of the year is late winter and early spring, before the summer monsoon starts, but conditions in the mountain habitats are probably not as dry as indicated by the data from low-elevation weather stations.

Coelogyne cristata 'Woodlands', CCM/AOS

An understanding of the general weather pattern in the habitat may help answer that frequently asked question, “How often should I water?” In their native habitat, the summer monsoon brings four to six months of extremely heavy rainfall. This is followed by a cool, dry winter monsoon, which also last s for several months. Although skies are generally clear and rainfall is low in winter over most f the region, habitats in the higher mountains are often bathed in fog and most for much of the year. Moss covers nearly everything in this moist environment. Cultivated coelogynes from this region should be watered heavily while actively growing, with little if any drying allowed between waterings. Water should then be gradually reduced after new growths have matured in the fall and limited in winter to occasional light waters or early morning mistings. More water should be given if the tip of the youngest leaves start to die back or if the pseudobulbs show signs of excessive shriveling. The leaves on the older pseudobulbs may naturally die during this time, but he tips of those on the newest growths should remain green. Likewise, slight shriveling should occur on the newest pseudobulbs. Too much shriveling indicates a need for more water and no shriveling at all indicates that the plant may not bloom because of too much water. Increase water gradually in spring after new roots begin to grow.

A balanced fertilizer mixed at one-quarter strength to one-half of the recommended strength should be applied weekly during period of active growth. Many growers recommend using a fertilizer lower in nitrogen and higher in phosphorus during the late summer and fall to promote better blooming the next season and to allow the new growths to harden before winter. In order to prevent salt buildup, leach the medium every few weeks during periods of heavier fertilizer applications. This is especially important in areas with hard water. Leaching is performed by first watering the plant normally, Then, an hour or so later, after accumulated salts have had a chance to dissolve, flush the medium with water equal to about twice the volume of the pot.

Growing Media
Plants may be mounted on cork or tree-fern slabs if humidity is high and plants are watered several times a day during hot, bright weather. However, most growers find it difficult to keep mounted plants moist enough in summer. Plants are usually grown in shallow pots or baskets filled with a porous medium through which water drains quickly. Fine to medium grade fir bark or tree-fern fiber is often used alone or mixed with varying amounts of additives such as charcoal, perlite or chopped sphagnum moss. We have had good success using baskets made from ¼ inch (6mm) mesh hardware cloth lined with a layer of coconut fiber or sphagnum moss. Our medium includes equal parts of fine and medium grade tree-fern fiber with about 10% fine charcoal, 10% perlite or sponge rock and 10% chopped sphagnum added. In our growing conditions, with strong air movement, this combination allows for more frequent watering without the medium's becoming soggy or drying completely between waterings. The tree-fern fiber does not break down as rapidly as fir bark, which means repotting is required less often. If the plant outgrows the basket, it can be hauled out en masse and merely placed in a larger basket without disturbing the roots. This can be an important consideration because many coelogynes do not like to be disturbed and may sulk for two or three years after repotting or dividing. Some growers suggest that thinning old pseudobulbs by cutting them out may be preferable to repotting as long as the medium has not broken down too far. When repotting is necessary, be sure it is done only when a flush of new root growth is starting. This will allow the plant to become re-established as rapidly as possible.

Miscellaneous Notes
Leaf-tip dieback may be a problem with many Coelogyne species and hybrids. While normally not fatal, it does cause unsightly plants and is usually an indication of a cultural problem instead of disease. Underwatering may cause these symptoms as may excessively low humidity. In most instances, however, the culprit is probably an excess of salt buildup in the medium that may be remedied by flushing the medium as previously discussed. These same symptoms may also be caused by root rot resulting from too much water, usually with old, broken-down medium. If uncertain as to the problem, the best action is to remove the plant from its container and check the condition of the roots. If everything is in good shape, the plant may be replaced in its container none the worse for the experience. Root rot is indicated if roots are soft and brown, and the root-ball will probably fall apart as it is removed form the container or basket. If this happens, it is obviously past time to repot. Because the plant is already out of the container, the grower is presented with a wonderful opportunity to remove the old medium, clean up and treat the diseased portion of the plant, repot is using new medium and a clean pot, and make a vow to never again wait too long to repot.

Coelogyne Memoria W. Micholitz 'Amy', AM/AOS

Hybridizing Notes
The entire genus has been generally ignored by hybridizers. To date there have only been about 40 hybrids registered. There was a small flurry of activity prior to 1920 when seven hybrids were registered. Between 1920 and the early 1990's there were only two or three. In 1950, Coelogyne Memoria W. Micholitz was registered. This is a hybrid between Coelogyne mooreana and Coelogyne lawrenceana, an intermediate- to warm-growing plant from Vietnam with large brownish-white flowers. The hybrid is dominated by the Coelogyne mooreana and the result is an intermediate-grower with large white flowers very reminiscent of Coelogyne mooreana produced in succession of a fairly long blooming period. Then in the 1970's, Coelogyne mooreana was crossed with Coelogyne cristata to make Coelogyne Linda Buckley but this hybrid is virtually unknown in collections today. Rather recently there have been a number of new hybrids registered, mostly using the warmer growing and smaller flowered species. Included in this list of relatively recent registrations is a cross called Coelogyne Unchained Melody. This is Coelogyne cristata by Coelogyne flaccida, an intermediate-growing species. This hybrid has actually been in cultivation for a fairly long time but most often mislabeled as Coelogyne mossiae which it superficially resembles. The two can be distinguished by the number of lip keels; two entire keels in the case of Coelogyne mossiae and three slightly undulate and basally deeply fimbriate keels in the hybrid. Coelogynes seem to offer wonderful opportunities for breeders who would like to tread where no one has gone before. Not only are there many opportunities for new Coelogyne hybrids, but there is exciting potential for crosses made between Coelogyne species and closely allied genera such as Pleione, Pholidota and Dendrochilum.

While the general cultural requirements previously discussed apply to most f the species from the region, there are some specific conditions required by each. When these are know, it is usually relatively simple to find an appropriate niche for each species in a cool- or intermediate-growing area. Therefore, following is a brief description of the plants and flowers, and a close look at habitat, climate conditions and specific needs of Coelogyne cristata, mooreana and mossiae.

Coelogyne cristata Lindley

This small to moderately sized sympodial epiphyte or lithophyte grows to 6 to 8 inches (15-30cm) tall with two dark green leaves at the top of each pseudobulb. The 6- to 12-inch (15-30cm) arched inflorescence is pendent to suberect and emerges from the base of mature pseudobulbs, usually before new growth starts. Five to eight long-lasting, showy flowers open simultaneously on each inflorescence. They are 3-5 inches (7-13cm) across, are sometimes fragrant and last four to five weeks if kept dry and cool. All lower parts are snow white with a crystalline texture and have wavy margins with reflexed tips. The lip is decorated with four to five yellow keels and golden-yellow blotches. For a time in the past, these plants were knows as Cymbidium speciosissimum D. Don.

The habitat extends eastward from about 75E Longitude in the Garhwal region of northern India, through Nepal, Sikkim, Assam, Bhutan and into the Khasi Hills of northeastern India. Coelogyne cristata is also reported in the mountains of northern Thailand. The habitat is usually at 5,250-8530 feet (1,600-2,600 meter) in moss forests where plants are found on both trees and rocks, often almost fully exposed to the sun.

Cultural Recommendations: Light
This species should be given light appropriate for cattleyas, 2,000-3,000 foot-candles. The heavy summer cloud cover indicates that some shading is needed from spring through autumn, but light should be as high as the plant can tolerate, short of burning the leaves. Conditions in the habitat are brightest during the winter dry season when skies are clear on more than half the days each month. Strong air movement is critically important at all times, and growers report ad dramatic improvement in growth if plans are placed near a fan for maximum circulation.

Coelogyne cristata occupies a habitat where summer days average 69-75F (21-24C), and nights average 58-59F (14-15C), with a diurnal range of 10-16F (6-9C). During the drier, brighter winter months, days average 51-55F (11-13C), and nights average 36-39F (2-4C), with a diurnal range of 15-16F (8-9C). Although these plants are able to tolerate below-freezing temperatures for short periods, growers should remember that if plants are subjected to very cold conditions, they are much less likely to suffer damage if they are dry at the time they are exposed. The cool, dry rest is essential for healthy growth and flowering, but it need not be quite as long or severe as indicated by climate data obtained from the habitat. Cultivated plans are successfully grown in conditions 10-12F (6-7C) warmer than indicated. In addition, water should be reduced for two to three moths in winter, and fertilizer should be reduced or eliminated until water is increased in spring.

Miscellaneous Notes
In nature, plants bloom in winter and early spring. Cultivated plants have grown into clumps 5 feet (1.5m) across, and one specimen was reported with more than 600 flowers. Being one of the largest-flowered species of the genus, Coel. Cristata made somewhat of a splash in collections and the cut-flower market about the turn of the 20th century but is now grown mostly by specialized or dedicated growers. This is probably because the species has long had a reputation of being difficult to grow and flower, which is more than likely the result of growers not fully understanding or meeting its cultural needs.

Hybridizing Notes
The chromosome count is 2n=40.

Coelogyne mooreana Sander

Coelogyne mooreana 'Brockhurst', HCC/AOS

This species is a moderately sized sympodial epiphyte that grows 12-18inches (20-45cm) tall with two glossy-green, heavily textured leaves per growth. The erect inflorescence is 15-20 inches (38-50cm) tall and emerges from between the leaves of new growths before the pseudobulbs have formed. Three to eight fragrant flowers, 3-4 inches (7-10cm) across are produced per inflorescence. They open simultaneously and are well spaced along the inflorescence. The flowerily segment are snow white except for a golden yellow blotch on the midlobe of the lip. The blossoms last in excellent condition for four to six weeks if they are kept cool, somewhat dry and in low light.

This species is a native of Vietnam and occurs at 3,950-4,250 feet (1,200-1,300 meters) in the Lang Bien Mountains near Dalat, about 150 miles (240 km) northeast of Ho Chi Minh City. At this elevation the probable extremes are 90F (32C) and 40F (5C).

Cultural Recommendations: Light
This species does well with light levels at the low end of those for cattleyas; 1,500-2,500 foot-candles. Strong air movement is critically important at all times. The heavy summer cloud cover indicates that shading is needed from spring through autumn, but light should be as high as the plant can tolerate, short of burning the leaves. In the habitat, winter is the brightest season.

In the native habitat, summer days average 77-78F (25-26C) and nights average 62F (17C), with a diurnal range of 10-14F (6-8C). The warmest days occur in spring, when days average 81-82F (27-28C). During the winter rest, days average 76-79F (25-26C), nights drop to 53-55F (12-13C), and the diurnal range increases to 24-25F (13-14C).

Miscellaneous Notes
It is difficult to understand why a species with such large attractive flowers is so rarely encountered in today's collections. This is especially true when one considers that it is also among the easiest of the genus to grow and flower, with no special cultural demands or requirements. In nature, plants bloom in spring or early summer.

Hybridizing Notes
Chromosome counts are not available.

Coelogyne mossiae Rolfe

Coelogyne Unchained Melody 'Buckingham' CCM/AOS is a relatively common primary hybrid of Coelogyne mossiae

These relatively small sympodial epiphytes or lithophytes are only 8-10 inches (20-25cm) tall with two leaves produced from the top of each pseudobulb. The arched to pendent inflorescence is about 8 inches (20cm) long and, in the manner of Coel. cristata, emerges from the base of the mature pseudobulbs before new growths start. Each inflorescence carries eight to 10 loosely arranged, fragrant, long-lasting flowers that open simultaneously. They are 2- 2.5 inches (5-6.4cm) across and are white with two yellow-brown blotches marking the midlobe of the lip.

This species is native to southwestern India at elevations between 7,000 and 8,000 feet (2,130-2,440 meters) in the Nilgiri and Pulney Hills. In its habitat, Magnolia and Rhododendron are common. Fog and mist occur frequently almost year round, and moss covers everything. Coelogyne mossiae grows both on moss-covered trees and on slimy, moss-covered rocks. The likely temperature extremes are 85F (30C) and 34F (1C).

Cultural Recommendations: Light
This species does well under cattleya light conditions or about 2,000-3,000 foot-candles. Light in the habitat is brightest during he winter dry season when skies are clear for more than half the days each month. Strong air movement is recommended at all times.

The warmest days of the year occur during the clear weather in late winter and early spring. In this season, days average 75-78F (24-26C) and nights average 51-55F (11-13C), with a diurnal range of 20-25F (12-14C). During the summer months, after the start of the rainy season, days average 68-70F (20-21C), and nights average 52-53F (11-12C), with a diurnal range of 16-17F (9C). During the winter rest period, days average 65-72F (18-22C), and nights average 46-48F (8-9C), with a diurnal range of 18-24F (10-13C). For cultivated plants a night temperatures in winter of 50-55F (10-13C) is adequate.

Miscellaneous Notes
This species flowers in cultivation during the winter and early spring months.

Hybridizing Notes
Chromosome count is 2n=54. Although Coel. mossiae is attractive, lasts well, and has relatively large flowers, it has rarely been used to make registered hybrids.

Other Species

Coelogyne nitida 'J&L', CHM/AOS is also commonly known as Coelogyne ochracea

Many smaller-flowered species, such as Coelogyne nitida and Coelogyne corymbosa, require about the same conditions as the species discussed here. In addition, there are species with large colored flowers and extremely fancy lips, such as Coelogyne lawrenceana and Coelogyne speciosa that require somewhat warmer conditions. Species from the tropical lowlands, however, require very warm, moist conditions year round. Among these are the large green-and-black-flowered Coelogyne pandurata, as well as species with large numbers of somewhat smaller flowers on pendent inflorescences, such as Coelogyne dayana and Coelogyne massangeana. These species are all worthy of more attention from growers and hybridizers, and none of them is particularly difficult if given the conditions they require. We hope the information presented here will give more growers the confidence to try the beautiful, large-flowered, white Coelogynes.


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- This article, written by Charles and Margaret Baker first appeared in the October 1994 AOS Bulletin, 63(10):1148-1155. The article has been edited to bring it up to date. The Baker's are well known in the orchid world for their cultural articles and books. They are the authors of Orchid Species Culture - Pescatorea, Phaius, Phalaenopsis, Pholidota, Phragmipedium and Pleione, Orchid Species Culture - Dendrobium, and Orchid Species Culture - Oncidium/Odontoglossum Alliance as well as maintain the website They have authored innumerable articles in the AOS Bulletin/Orchids, Orchid Advocate, Orchid Digest, Orchid Hunter, and the Oregon Orchid Society Bulletin. - Ron McHatton, AOS Director of Education and Regional Operations, 2009.