Orchid Care: Cymbidium
These orchids are prized for their sprays of large flowers, used especially as cut flowers or for corsages in the springtime. There are two main types of cymbidiums: standards and miniatures. Where summers are warm (above 90º) only miniatures are recommended, since they are more heat tolerant than standards, and bloom in warmer weather.
Unlike many cultivated orchids, cymbidiums are semiterrestrial plants. They have a growth period in the summer, needing 60º – 85ºF, medium to high light, regular applications of fertilizer and moist potting medium such as fir bark or peat moss. When repotting, soak any medium overnight before using. Cool fall nights (to 40º), "bloom-booster" fertilizer or no fertilizer, all induce flowering. Miniature cymbidiums can stand temperatures 5º – 10º higher.
TEMPERATURE is the most critical factor in blooming cymbidiums of either type. During the summer, standard cymbidiums are usually grown outside in semi-shade, where day temperatures should be 75º - 85º F , but night temperatures in the late summer to fall (August to October) must be 50º to 60º F to initiate flower spikes. Optimum temperatures in winter are 45º - 55ºF at night and 65º - 75ºF during the day. When in bud, temperatures must be as constant as possible, between 55º and 75ºF. Miniatures can stand 10ºF higher than standards and still bloom well. Most cymbidiums can stand light frosts and survive, but it is not recommended. Bring them inside when temperatures dip to 40ºF, to a bright and cool location; in mild climates they may be grown outside year round.
LIGHT is also very important for growing cymbidiums. Coming from cool and bright areas in Asia, they need high light but cool temperatures. In many of our climates, the high level of light cymbidiums need is accompanied by high temperatures in the summer, which may cause the plants not to bloom. There are several ways of counteracting this: spray the plants with water during the summer afternoons to cool the plants down, shade more heavily, and increase air movement. The maximum amount of light possible, short of burning, should be given to the plants. This means only light shade during the middle of the day, or about 20% shade. In cool areas (e.g. coastal California), full sun is tolerated. Leaves should be a medium to golden green in color, not a dark green. Keep shadier in the winter, especially if in bud.
WATER must be provided at all times to cymbidiums. As semi-terrestrials, they need a fairly constant supply of moisture. Since they produce all their vegetative growth during the spring and summer months, they need the most water then, Water heavily during the growth season, keeping the potting medium from drying out completely, and reduce water when the pseudobulbs are completed in late summer. Keep barely moist during the winter.