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Growing the exotic Coelogyne Orchid

orchidsCoelogyne orchids are one of the most important orchid group, with approximately 150 species distributed throughout the southeast Asia area, China and the Philippines. It is a group which includes a number of horticulturally important species that have been in great demand by orchid collectors since their introduction in the last part of the 1800s. It also includes some considerable number of botanical type plants which are seldom found in collections. Coelogyne orchids are popular in collections due to their mostly fragrant, free flowering, and showy inflorescences.

The orchid genus was found by Dr. Lindley in 1825, with the well-known horticultural species Coelogyne cristata as the type specimen. The generic name Coelogyne was suggested by the prominent depression in the stigma and was derived from the Greek kailos, “hollow,” and gyne, “a female.” Plants of this group are stemless, characterized by tufted, crowded pseudo-bulbs with two or three papery leaves. The flowers are in racemes, mostly pendent, medium-sized, usually of delicate white, yellowish, and greenish color, often suffused with brown. The lip is three-lobed with erect lateral lobes.

Many species are very large epiphytic (occasionally lithophytes) plants which have quite showy, often fragrant flowers. They have large flattened pseudobulbs with one to two large, leathery leaves which are plicate. The pseudobulbs are often well spaced on a rather long, creeping rhizome so they are often best grown in a large basket or slab so they can roam around easily.

Most of the Philippine members of the genus, of which there are about 20, are usually small flowered plants with greenish and yellowish flowers. There are two species, however, C. asperata and C. merrillii which produce flowers of substantial size and prove of interest to some collectors.

C. asperata is indigenous to Samar, Mindanao and Negros, as well as in Borneo, Sumatra and New Guinea . This is a large plant that often grows three to four feet tall and has flowers 11/2 to two inches across. It is native to the hot, low coastal regions.

C. merrillii, on the other hand, is a mountain species and is found at an elevation of from two thousand to seven thousand feet. This species was named in honor of Dr. Merrill, the distinguished botanist, who has contributed extensively to the study of the Philippine flora.

Coelogyne marmorata is representative of a number of similar native Coelogynes, all of which are indigenous to the mountains of northern Luzon and Benguet subprovince. Two other similar species, C. integerrima and C. chloroptera, also have shiny yellow green bulbs and sprays of from five to ten light green flowers.  C. marmorata and C. merrillii are usually found growing on moss-covered trees of the cool humid areas of the mountain regions and, therefore, cannot be grown successfully in the hot climate of Manila . For hobbyists, some of the warm growing species are recommended for warm lowland temperature; while the cool growing species are recommended for cool upland temperature.

How to Grow this Plant.

 

Light. Coelogyne grow in about 60% sunlight or brighter, and needs to be protected from direct heat of the sun.

 

Temperature. Most Coelogyne species are cool growing, and growers may find it difficult to acclimatize plants in the lowland.  However, there are also some species which are warm growing or have adjusted to the lowland condition and can therefore be grown in the warm lowland condition.

 

Potting Techniques. Coelogyne could be planted either in plastic or clay pots, and the plant have to be properly stalked or anchored in the center of the pot using GI or copper wires. The plant must also be tied properly into the wire stalk to prevent it from moving during watering. Stalking is very important because insufficiently stalked plants will fail to root. A matured plant can be divided into individual plants with 3-4 pseudobulbs. Sterilized pruning shear by washing in soap and water and wiping with 70% ethyl alcohol when dividing plants to prevent virus infection.

The wound needs to be sealed with fungicides paste to prevent entry of fungal diseases into the wound. Use combination of charcoal, broken clay pots, cracked limestone, and coconut husk chips as potting medium.

 

Water. Water plants moderately; about once every 3 days. Keep the growing area humid by providing companion plants or wetting the surrounding areas and companion plants. Do not over water or else the plant will rot. Ventilation or wind movement is very important in drying the plant. Allow air movement in the nursery or garden and provide enough space between plants.

 

Fertilization. Fertilize plants with the usual dose of orchid foliar fertilizer spray, about 1 teaspoon per gallon of water, and spray it on the plant once a week, usually after watering.

 

Pest and Disease Management. Regularly check plants for insect pests or diseases. Plants maybe attacked by sucking insects like aphids, scales, mealy bugs or mites. For preventive treatment, spray plants with dilute Perla soap solution once a week, maybe together with the fertilizer. However, for insect pest infestation, spray plants with Lannate or Sevin insecticides with formulation based on the label. For fungal diseases, do not overwater plants. During rainy season, spray plants with Dithane or Captan fungicides as a prophylactic against fungal rots. Allow air movement, and always remove all dead or decaying plant parts from the plant.

 

Propagation. Coelogyne could be propagated through division of pseudobulbs. Care needs to be observed in dividing plants, especially using only sterilized pruning shears by washing them first in soap and water and wiping with 70% ethyl alcohol. Plants are then divided into plants with 3-4 pseudobulbs each and mounted on clay pots with charcoal. However, the fastest and efficient way of propagation is through seed culture technology in the laboratory. Flowers of selected plants are pollinated, and their seed capsules are allowed to mature. Coelogyne seed capsules mature in about 3 months. They usually contain thousands seeds. The seeds are then sown in the laboratory in a glass vessel with an artificial nutrient medium.  Seeds will germinate in one month’s time. Seedlings will be ready to be planted in the nursery after 8 months.