In their native habitats, dendrobium orchids (Dendrobium spp.) cling like monkeys to rainforest trees. Since plants of this genus vary widely, the species are divided into classes, such as Latourias and Nigro Hirsutes. Latourias frequently appear leggy with leathery leaves at the top of tall canes, and ruffled flowers in white, yellow, or yellow-green spotted with purple. The more compact Nigro Hirsutes, or Formosae, have leaf sheaths speckled with black stubble and less frilly blooms that also run to white and yellow. Dendrobiums are usually grown as houseplants except in U.S. Department of Agriculture plant hardiness zones 10 to 12, where they are hardy.
Let There Be Light
Dendrobiums like sunlight for four or five hours per day, but midday sun can burn their leaves. It is best to grow them on east- or west-facing windowsills that the sun’s rays only reach in early morning or late afternoon. If you need to use a south-facing windowsill, place a sheer curtain between the plants and the glass. The shorter types will also flourish under grow lights with at least four side-by-side fluorescent tubes. During the summer, dendrobiums can be kept outdoors beneath the high shade of a tree, arbor or porch roof.
Some Like it Hot
Latourias like a lot of warmth, while Nigro Hirsute dendrobiums prefer to be kept a bit cooler. If you set the plants outdoors over the summer, bring the Latourias inside when the nighttime temperature drops below 60 degrees Fahrenheit. You can leave Nigro Hirsute types out until the temperature threatens to fall below 50 degrees F. Both will appreciate the thermostat being turned down to the 60s F at night while they are indoors. Latourias will tolerate temperatures up to 90 F during the summer, but Nigro Hirsute varieties resent heat above 85 F.
Water, Water Everywhere
Dendrobiums should be grown in clay pots filled with a fast-draining medium such as fir bark. If you have top-heavy Latourias, you may also need to add stones to the bottoms of the pots to keep them from tipping. Bark mediums tend to dry out quickly during the summer. If you water the plants in the morning and their medium is thoroughly dry by noon, continue to water them every morning. Otherwise, wait until the medium is dry at least 1 or 2 inches down. Gradually reduce the plants' water as the daylight hours decrease, since they shouldn’t need watered more than once every five days when they are indoors during the winter. Latourias don’t require a rest period, but Nigro Hirsute types will perform better if given a two-week winter nap with no water and temperatures of 55 to 60 degrees F. Dendrobiums like damp air, so they should be set on humidity trays when indoors or located in a naturally humid area such as the bathroom or a shelf over the kitchen sink.
You can feed your dendrobiums once a week during their growth period from April to October, with a 20-20-20 water-soluble plant food at one-fourth the strength recommended on the container. Generally, that would be about 1/4 teaspoon of fertilizer per gallon water. Don’t feed them at all from November through March.
- American Orchid Society: Dendrobium
- Johnson’s Florist and Garden Centers: Growing Dendrobium Orchids
- St. Augustine Orchid Society: Touring the Latourias: An Overview of New Guinea Dendrobiums
- Camp Lot a Noise Tropicals: The Hairy Tale Continues
- St. Augustine Orchid Society: Dendrobium Culture
- Bribie Island Orchid Society: Latouria Type Dendrobium Orchids
- University of Illinois Extension: Dendrobium
- The Plant Book; Susan Page and Margaret Olds
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