The Dendrobium family of orchids is enormous, including plants that produce multitudes of tiny flowers on tall branches and plants with only a few big, showy blossoms on each stem. The flowers can be white, purple or yellow. Orchids go through active periods, when they flower almost continually, and dormant periods of six to eight weeks' duration, when they don't flower at all. Follow these simple steps for beautiful and healthy Dendrobiums.
To pot a Dendrobium, mix 2 parts potting soil with 1 part peat moss and fill the flower pots about three-quarters full. Dendrobium orchids must be planted in soil that drains well.
Put one orchid into each pot and fill in around the roots with more of the potting soil mixture.
Put a single layer of pebbles in the metal or plastic tray, and then add enough water to fill the tray about halfway.
Put the orchids in their pots into the sink, and water them well, letting any excess drain out.
Put the orchids into the tray with the pebbles and water. Set the tray where the orchids will get bright light. If you put the tray in a window, make sure that the plants get direct sunlight for only about half the day.
If you're growing them under artificial lights, set the Dendrobium orchids directly under four 40-watt incandescent lightbulbs.
Ideally keep the air temperature in the room where the orchids are growing between 80 and 90 degrees Fahrenheit during the day, and between 60 and 65 degrees at night.
Keep the plants moist at all times during their active period. When they go dormant, let them dry out completely between waterings. Keep the tray half full of water at all times to maintain proper humidity levels for the plants.
Fertilize the plants once a week while they are actively flowering. Combine the fertilizer with water to equal one-half to one-quarter the strength recommended on the product packaging. When they go dormant, stop fertilizing the plants.