Dendrobium (den-DROH-bee-um)
The Spray Orchid

Dendrobiums are among the most commonly encountered orchids in the retail trade. Like most other cultivated orchids, dendrobiums are epiphytes, or air plants. They have well-developed water-storage organs (pseudobulbs), often called “canes” for their upright, leafy appearance. They should be potted in porous, free-draining media. There are many different types of dendrobiums available to the specialist grower. However, hybrids involving Den. phalaenopsis are what you will most often encounter.

Light
Sufficient light is important for healthy growth and flower production. Provide bright light, to 50 percent sun. In the home, an east, west or lightly shaded south window. In a greenhouse, about 30 to 50 percent of full sun. Under lights, four 40 watt fluorescent tubes and two 40 watt incandescent bulbs directly over plants. Plants should be naturally erect, without need of (much) staking, and of a medium olive-green color.

Temperature
Mature plants need a 15 to 20 F difference between night and day. Provide nights of 60 to 65 F; days of 80 to 90 F. Temperatures up to 95 to 100 F are beneficial if humidity and air circulation are increased. Low temperatures (below 50 F) may cause leaf drop.

Water
Keep evenly moist while in active growth. Allow to dry between waterings after growth is mature (indicated by terminal leaf).

Humidity
Dendrobiums need 50 to 60 percent. In the home, place on trays over moistened pebbles. In greenhouse, use a humidifier if conditions are too dry

Fertilizer
Must be provided on a regular basis because most potting media have little. The exact fertilizer you use will depend on the mix in which your plant is growing. A good general rule is to use a balanced (10-10-10, 12-12-12 or similar ratio) fertilizer “weakly, weekly.” That is, fertilize every week at one quarter to one half of the recommended dilution.

Potting
Should be done every two to three years in spring before mix loses consistency (breaks down). Pot firmly in media that have good aeration and ample drainage, allowing enough room for two years’ growth. Dendrobiums grow best in pots small for the size of the plant.

From The American Orchid Society Cultural Guide