Dendrobium is one of the larger families of orchids with more than 1,000 known varietals. Dendrobium orchids throw long arching spikes of flowers from a thickened and segmented main trunk from which long ovoid leaves grow at interspersed intervals on opposite sides of the trunk. The range of colors and patterning of blooms is immense and Dendrobiums grow in soil, in air on tree trunks or occasionally in either. Like all orchids they thrive in moist and tropical to temperate climes.
Dendrobium orchids like most orchids thrive in bright indirect light with some shade cover. Whether growing indoors in pots, outdoors in the crevice of a tree or in the ground, you want to provide and maintain this level of indirect or dappled light exposure. Harsh direct sunlight can scorch the leaves, wilt the blooms prematurely and dry out the roots of the orchid, which can kill it or severely impede its blooming.
Water and Fertilize
Mimicking the environmental moisture of their natural habitat can be tricky but smart placement and a few household items can help. If growing in a pot or in a tree crevice, you want to regularly water your Dendrobium orchid every 10 to 12 days or so by allowing tepid water to run through the roots. Once a month you should add a dose of good quality orchid fertilizer to the water, letting it dissolve and then pouring through the plant slowly and allowing the excess to drain away. Follow the directions on the label of your product and do not overfeed, as it will not produce a healthier or more abundant bloom. Never apply orchid fertilizer directly to roots, as it can burn and kill them. For the rare occasions that Dendrobiums are grown in the ground, maintain a uniformly slightly moist but never consistently wet soil that has been amended with bark, sand, orchid charcoal shards and perlite to increase its drainage capacity and lightness, which allows the roots to breathe.
Caring for Blooms and Foliage
Dendrobiums typically bloom once or sometimes twice a year for an extended period. When the bloom begins to fade, do not cut it off immediately. Allow the bloom and stem to begin to die back. It is releasing nutrients back into the leaves and roots to power future growth and bloom. Once the stem has browned and withered you can cut it back at the base with clean sharp shears. As with blooms, when leaves begin to yellow and die back, allow them to fade naturally. When they are very shriveled and yellow they will lift off of the trunk with only a very gentle pull.