Cymbidiums are semi-terrestrial orchids that can be found growing in tropical and subtropical Asia (northern India, China, Japan, Malaysia & the Philippines) and Australia. They are frequently used as cut flowers in arrangements and corsages, and their blooms come in a wide variety of colors, including white, orange, pink and yellow. Cymbidiums can be classified as either standard or miniature depending on their flower type. Standard cymbidiums have large flowers, about 4 to 5 inches wide. Miniature cymbidium blossoms are about half the size of the standard flowers. They are also more heat tolerant and will flower at warmer temperatures.
Cymbidiums require high light during their active growing period in spring and summer and to initiate blooming, but avoid placing them in direct sunlight. Sunburn can occur rapidly if placed in full sun. Foliage will be medium green when light is optimal. Dark green leaves indicate too much light.
Most Cymbidiums are commercially available as cool-growing orchids. They can be grown outside in partial shade and tolerate temperatures from 75 to 85 degrees F. At night, temperatures should be about 50 to 60 degrees F. Bring the orchids inside just before the first frost. During the winter, temperatures should be kept between 60-65 degrees F during the day, and 50-55 degrees F at night. Cymbidiums typically bloom during the fall and winter months and will not initiate blooms unless there is approximately a 10-15 degree temperature difference between night and day. The plants can be put outside again in spring when night temperatures are consistently in the 40s. Miniature Cymbidiums will flower at temperatures 5 to 10 degrees higher than Standards.
Cymbidiums require a constant supply of water in spring and summer when they are producing their vegetative growth. Reduce the amount of water as fall approaches, and keep barely moist in winter. To water the plant, place it in the sink and flood it for a minute or so with lukewarm water. Never use cold water. Allow the water to drain thoroughly. Do not use salt-softened water. Water your plants in the morning so the foliage will be dry by nightfall. Wet leaves can encourage disease issues.
Cymbidiums prefer humidity at 50% or higher. Good air movement is important to prevent fungal infections and insect issues. Do not crowd your plants so there is air circulation around them. If humidity in the home is below the 50% threshold, you can place your plant in a shallow tray of pebbles with water on the bottom. Be sure that the bottom of the pot is not in the water or the roots will rot.
Cymbidiums can be fertilized every two weeks after watering from March to September, and once every three weeks in late winter and fall. In winter, feed only once a month. Use a balanced orchid fertilizer such as 20-20-20.
Repot your plant every two years or when the potting medium has decomposed. Repot after flowering in spring or early summer. Choose a sterile plastic or clay pot with bottom drainage holes that will accommodate about two years’ growth. Use a commercial orchid potting medium that is labelled for Cymbidiums. This will usually be medium grade fir or sequoia bark based and may contain horticultural charcoal and perlite. Clean the roots and remove any dead root material with a sterile blade or sterile pruners. Always sterilize your tools between plants so as not to spread disease.Use a suitable disinfectant such as bleach. Cover the bottom of the pot with a layer of potting medium. Place the plant in the pot with the oldest stems (pseudobulbs) at the edge of the pot. Cymbidiums are sympodial orchids that grow horizontally; therefore, it is important to give the newer, active pseudobulbs room to develop and grow in the pot. Spread the roots within the pot and fill the pot with culture medium, working it around the roots and tamping firmly with the fingers. If you are dividing a large plant, assure that each division contains at least three and preferably five or more pseudobulbs. Do not overpot. Label the plant and record the repotting date on the label to keep track of when it needs to repotted again.
Cymbidiums will bloom once per year around late fall or winter and early spring. Flower spikes are initiated by the cooler day and night temperatures and with proper care can last for several weeks. Once the blooms have faded, the flower stalk can be cut down to the base.