Gardeners all across the country are envy our Northern California climate. Warm days and cool nights make this a perfect spot not only for human habitation, but also for growing cymbidium orchids.
What Cymbidiums Like
Unlike tropical orchids, such as the popular phalaenopsis and dendrobium, cymbidiums are native to the cool mountain regions of Asia and Australia. They need nighttime temperatures of 45-55° F to produce their spectacular flowers. High daytime temperatures don't seem to harm these hardy orchids, so long as it cools off at night.
Cymbidiums prefer filtered light, but will tolerate extreme heat as long as they're protected from direct sunlight. You can tell if your cymbidiums are getting too much or not enough light by the leaf color. The foliage should be a bright, yellow-green color. Dark green indicates not enough sun, while yellow, spotted foliage indicates too much. Many people have success growing cymbidiums on the east side of the house, where the plants receive full morning sun but are shaded from the stronger afternoon sun.
How They Grow
Cymbidiums grow from egg-shaped pseudobulbs that rest on the surface of the potting medium. Strappy, grass-like foliage emerges from these pseudobulbs. Individual leaves sometimes grow to 5 feet or more, depending on the variety. Their foliage makes a handsome background for other plants.
The Show Begins!
In late winter, flower buds form low on the plant and quickly grow into tall flower spikes. If your cymbidiums are growing outdoors, protect flower buds from hungry snails. As you might expect, they are stunning in bloom, with as many as 35 individual blooms on a single spike. Each flower spike can last up to 8 weeks on the plant, and as long as a month when cut and displayed indoors in a cool location.
The individual flowers range in size from 2 to 5 inches in diameter, depending on the variety. Plant breeders have developed a wide spectrum of colors, including white, green, orange, burgundy, bronze, pink, and purple.
The Cymbidium's Diet
There is a trick to commanding peak performance from your cymbidium orchid plants. When plants are actively growing, March to October, cymbidiums need ample water and frequent applications of a high-nitrogen fertilizer. Fertilize with a complete liquid fertilizer (22-14-14) every 10 days from January to July. From August through December switch to a low-nitrogen, bloom-inducing fertilizer (0-10-10) applied on the same schedule.
Repotting Your Orchid
Transplant only when the pseudobulbs crowd the pot and after the blooms are finished for the season. When dividing the plants, keep a minimum of three healthy pseudobulbs per division. The selected bulbs should be solid and firm in texture with some roots attached. Place the divisions in fresh potting soil in a small pot that allows only 2-3 inches between the bulbs and the side of the pot, as they prefer to be a bit crowded. The preferred soil mix is 2 parts composted bark, 2 parts peat moss, and 1 part sand. Perfect drainage is a must. It's best not to use a saucer under your cymbidium orchids so the pot doesn't sit in excess water. If you must use a saucer, place a layer of gravel under the pot to keep it up out of standing water.
Cymbidium will survive a frost, but if you expect a hard freeze, pull the plants under the eaves for protection. Don't throw out plants that have slight frost damage -- new growth will emerge from the pseudobulb as soon as the weather warms again.
Photo by former managing editor Kim Haworth/National Gardening Association