The Dendrobium genus of orchids contains over 1,200 species. The name derives from a Greek word that means "one who lives in trees." The genus is so large it is divided into sub-classes according to its floral and vegetative characteristics. "Den-phals" and "antelope types" are two common hybrid sub-classifications. Dendrobiums are an easy orchid to grow with some general orchid knowledge about light, air, water and food.
The natural habitat of Dendrobium orchids is in the canopy of tall trees where they can receive as much light as possible. Home growing conditions can mimic this by keeping orchids out of full shade. Morning sun with some afternoon shade is beneficial. Orchids grown in sufficient light have yellowish-green leaves and strong upright growth. Dendrobiums will not bloom abundantly in dim or insufficient light. They grow well under trees with a high canopy.
Orchids do not grow in soil; unlike many other plants, their roots need air. The potting medium for Dendrobiums should be very porous, open and have exceptionally good drainage. One mixture is two parts granulated charcoal, two parts sifted perlite and one part sterile potting mixture. They are cannot thrive in a stagnant growing medium. Air circulation is essential for all parts of the plant. Some growers use an overhead fan to gently move the air.
The American Orchid Society reports that more orchids are killed by incorrect watering than anything else. Dendrobium orchids of all varieties should be watered only when dry to the touch. Let them go dry between watering. Time varies according to individual growing conditions. Plastic pots feel much lighter when it is time to water. Irrigate the plants freely until water runs through the drainage holes. This also flushes out salts. Water Dendrobium orchids thoroughly at least once a month.
Dendrobium orchids bloom more abundantly when they are fertilized regularly. Typically this is once a week during the summer and every two weeks in the winter. Water the plant first and then apply a diluted mixture. There are many types of orchid fertilizers available at garden centers. Dilute commercial fertilizers to 1/2 the recommended strength. A compost tea made with one tablespoon compost to one gallon of water will provide balanced nutrients.
Dendrobium orchid roots grow over the edge of the pot occasionally but it does not indicate it's time to repot the plant. Repot when the body of the plant has grown over the edge or the planting medium breaks down. The beginning of the growing season is the best time to repot orchids. Gently remove the plant and the old potting medium and cut away any dead, brown roots. Place it in the new pot and gently surround it with new growing medium. Water lightly until the orchid establishes itself.