Nearly all Dendrobium orchids are epiphytes; in their natural habitat they grow on trees. A few are lithophytes; they naturally grow on rocks. Both epiphytes and lithophytes use their roots more as a means of anchoring themselves.
Dendrobium orchids are the most challenging to grow and flower generally do well in the home; however, they require plenty of warmth and humidity during their rather short growing season and a cool, dry rest afterwards They also require good air circulation and ventilation.
Temperature and Light
Growers consider 45° to 50° F to be ideal temperatures during winter. Early in the year, you will notice buds starting to swell at the nodes along the cane. If the temperatures during the winter were too high, the buds will open to produce little plantlets, rather than flowers.
Dendrobium orchids require bright, natural light during the active growth period and shelter from intense sun.
Water, Fertilizer, and Humidity
As spring approaches and the weather begins to warm up, encourage rapid growth by moving the plant to a warmer location in the house. Water carefully at first, letting the compost dry out between waterings. This does not mean that you should give your orchid a little bit of water at a time. When you water, do so thoroughly until water runs out the drain holes in the bottom of the pot; then let the compost dry out almost completely before watering again. With more growth, slowly increase watering and give your orchid plenty of light to encourage a healthy, firm new cane. Water regularly through summer until growth is complete in the fall, which is demonstrated by a small single leaf at the end of the cane. At this time, reduce watering. Stop watering completely by winter. This cycle begins with the orchid looking forward to a cool rest again. Water abundantly during the growth period, particularly in summer.
Optimum humidity for the Dendrobium Orchid is 60 to 70% during active growth.
Generally grown in a compost of pine bark, Dendrobiums require regular fertilization and should be fed at least twice a month in summer and while in the growing mode. They require a nitrogen-rich fertilizer of the 30- 10-10 type, diluted to half of the recommended strength. During the rest period just after flowering, do not fertilize at all until new growth shows.
The ideal time to repot a Dendrobium is in spring a couple of weeks after you notice the roots beginning to grow again. Repotting must not be done during the rest period. Use bark when repotting with as small of a pot as possible.