I was leafing through Pat Welsh’s wonderful resource book entitled Southern California Gardening – A Month-by-Month Guide, Chronicle Books, 2000, when my eye caught a side bar on “How Cymbidiums Came To California.” It’s something I never considered and thought it might also interest my blog readers. So here it is in its entirety.
Cymbidiums are largely terrestrial orchids native to cool tropical jungles, from the Himalayas eastward through southern Asia. For at least two hundred years they were hybridized and grown in cool greenhouses by English collectors. During the Second World War a great many varieties were sent to Santa Barbara to save them from the bombs. It soon became clear that cymbidiums flourish outdoors in Southern California. They multiplied so rapidly that when the loaned varieties were sent home after the war, many more plants were left here, to continue to grow in our gardens. They’ve since become one of our best plants for winter and spring bloom.
Not all cymbidiums bloom every year. (You need three plants to be assured of annual bloom.) But some gardeners complain that none of their cymbidiums ever bloom. These plants are remarkably easy to grow, but they do have certain requirements. Here’s how to make them bloom.
Switch Fertilizers in September: Beginning on the first of September Switch fertilizers from a high-nitrogen formula for growth to a formula higher in bloom ingredients, such as 15-30-15 or 10-30-10. (If you’re feeding with high-nitrogen slow-release tablets continue their use, but once every two or three weeks treat the plants additionally with 0-10-10 or 2-10-10 liquid.) Cymbidiums continue to grow year-round so they always need some nitrogen, but a higher percentage of phosphorus and potassium now will encourage development of bloom spikes.
Keep Cymbidiums in Bright Light: Don’t keep cymbidiums in too much shade. If you’ve sheltered yours from hot sun under a tree, during the summer, bring them out into more light now. Along the coast they can take full sun, though they’ll need protection during the Santa Ana or sudden heat wave that almost always strikes sometime In September. Inland they need protection from the burning rays of midday sun -under 50 percent shade cloth or in a lath house is ideal. They often can take more sun than we give them. If your cymbidiums have dark green leaves, chances are you’re keeping them in too much shade. Give them enough light to turn the leaves a yellowish color. Spread the plants apart, and allow sunshine to hit their pseudo bulbs. Crowded plants won’t bloom as well because the leaves shade the bulbs. (Trim off dead leaves and brown tips, but don’t cut off or shorten healthy leaves. Cymbidiums need all their leaves to nourish the pseudo bulbs.)
Provide a Wide Range of Temperatures. Large-flowered cymbidiums need a daily temperature range of at least 20 degrees during the hottest time of the year in order to trigger bloom. What they like best is nights that drop to 45° or 55°F and daytime temperatures of 80° or 90°F. Our gardens provide adequately warm days and cool nights, but our patios or porches often do not. They’re too warm and sheltered at night. So situate your cymbidiums away from protective house walls and don’t keep them indoors, or they’ll never bloom.
Recent advances in hybridizing have broken the size barriers and expanded the bloom seasons of cymbidiums. Standard or large varieties usually don’t bloom until they’re 4 feet tall. Miniatures, on the other hand, will bloom in 4-inch pots when they’re only a foot tall and may produce two to four spikes of twelve to twenty-four flowers on each. (Plants with flowers less than 3 Inches across are classed as miniatures.) Miniatures tolerate hot weather better – up to 115°F – and will bloom when night temperatures in summer are as high as 65 of higher than standard cymbidiums require to trigger bloom. Miniatures come into bloom in November and continue into March, while standards bloom from January to mid-May. So, if you have had problems getting cymbidiums to bloom in your climate zone or on your patio or porch, try the small-flowered varieties. They bloom more readily both inland and along the coast, and the bonus is that some of their flowers are highly fragrant.
Meanwhile, water cymbidiums enough to keep the pseudo bulbs from drying out and shriveling. Water should always drain right through. Cymbidium roots can’t survive in a puddle. As the spikes grow, stake them so they don’t get broken, and protect the plants from slugs and snails.