Most species have a moderate to fast growth rate. The best time to plant is either at the very beginning of the growing season or after the orchid has finished flowering. Dendrobium orchids make good houseplants and are fairly easy to grow, though they can be picky about their environment. Thus, paying close attention to their growing conditions is key for a healthy, well-blooming plant. In general, these orchids like small pots where their roots can be somewhat cramped, and they need to be by a bright window if you’re keeping them indoors. Plan to water and feed your orchid often during the growing season but then back off in the winter months.
Light
In native settings, these plants grow well in partial sunlight. But indoors they’ll likely need to be by your brightest window—preferably a south-facing window—to bloom well. The appearance of many tiny offshoot plants (known as keikis, pronounced “kay-keys”) on relatively young, small canes can mean the plant isn’t getting enough light. On the other hand, if you see yellow leaves, you might have given the plant too much direct sunlight.
Soil
Orchids don’t grow in typical potting soil but rather in a special mixture that mimics their environment in the wild. Use a commercial orchid potting medium, which generally contains peat moss, perlite, or fir bark. Or make your own using those ingredients. Make sure the medium has aeration and is well-draining, so the roots aren’t left in too much moisture for a lengthy period of time.
Water
During the growing season, these plants like moisture but shouldn’t sit in a saturated medium. Overwatering can lead to root rot and ultimately cause the plant to yellow or wilt. To determine when you should water, simply stick your finger in the medium. If it feels wet, wait to water until it has dried out slightly. During the winter months, you can put a few more days in between your regular waterings, but don’t let the medium dry out entirely. Watering with distilled water or collected rainwater is a good idea, as tap water can cause salts and minerals to build up in the pot.
Temperature and Humidity
Dendrobium orchids like warm climates and grow best with daytime temperatures between 70 and 85 degrees Fahrenheit, with a nighttime drop of about 10 degrees. They might be able to withstand slightly cooler nighttime temperatures down to 50 degrees Fahrenheit, but prolonged exposure to cold isn’t ideal. Many types, however, do require a winter rest period where the plant is kept at about 55 degrees for several weeks in order to prompt reblooming. Dendrobiums prefer a humidity level between 50 and 70 percent (with a minimum of 45 percent). Brown leaf tips can be a sign that the air is too dry for your orchid.
Fertilizer
Feed regularly during the growing season with a balanced orchid fertilizer, following label instructions. At the end of the growing season, reduce fertilizer by about half.
Types of Dendrobium Orchids
Dendrobium orchids are classified into six distinct groups, each of which has different characteristics and care needs. It is important to understand what group your orchid falls into in order to give it proper care:
Dendrobium phalaenopis is the most popular group, comprising most of the commercial dendrobiums offered for sale. These are evergreen species that like warm conditions and usually bloom in the fall, with a spring rebloom possible if the plant is given a three- to four-week rest period at lower temperatures and drier conditions. Species in this group include. D. affine, D. biggibum, D. dicuphum, and D. williamsianum.Dendrobium spatulata is another evergreen group, but comprised of species that may bloom several times a year. Species that fall into this group include D. antennatum, D. canaliculatum, D. discolor, D. gouldii, D. johannis, D. lineale, D. stratiotes, D. strebloceras, and D. taurinum. Unlike other groups, this group does not require the winter rest period in order to rebloom.Dendrobium is divided into two sections. Group 1 includes a select group of species with pendulous stems. They usually actively flower in summer and drop their leaves in winter. These orchids require a winter rest period with cooler, drier conditions. Species in this group include D. chrysanthum, D. friedricksianum, D. nobile, and D. wardianum. Dendrobium group 2 comprise species that are fully deciduous and which should not be watered at all in winter. Species include D. anosmum, D. crassinode, D. falconeri, D. fimbriatum, D. findlayanum, D. heterocarpum, D. loddigesii, D. moniliforme, D. parishii, D. primulinus, and D. transparens. Callista group includes species such as D. aggregatum, D. chrysotoxum, D. densiflorum, D. farmeri and D. thyrsiflorum. These need warm conditions in summer, but reduced temperatures and drier conditions in winter.Latouria group includes species such as D. atroviolaceum, D. macrophyllum and D. spectabile. Flowers are commonly yellow-green in color; these species need a winter rest period.Formosae group includes species such as D. bellatulum, D. dearii, D. draconis, D. formosum, D. infundibulum, D. lowii, D. lyonii, D. margaritaceum, D. sanderae and D. schuetzii. Orchids in this group generally require cool to moderate conditions year round: 50- to 60-degree nights, days no more than 85 degrees Fahrenheit.
Species falling outside these groups include D. linguiforme, D. tetragonum, D. gracillimum and D. cuthbertsonii. With these, it’s generally safe to allow them to dry out and go dormant in winter, providing them moderate temperatures during their growing season.
Pruning
These plants generally send up at least one new upright cane each year. After the flowers fade, they can be clipped off where they join the canes, but don’t cut off old canes, as they store nutrients and water to keep the orchid healthy. Clipping this stem off does not promote reblooming, as it does with some other types of orchids. Old canes also will sometimes flower or produce tiny offset plants, called keikis (pronounced “kay-keys”), that can be potted on their own after they develop roots.
Propagating Dendrobium Orchids
If your plant has at least four canes bearing healthy leaves, you can divide it. Here’s how: Another propagation method is to simply prune away the small offset plants (keikis) that sometimes appear at the base of old, mature canes and replant them in their own pots. However, these offsets will take longer to become mature, flowering plants than if you create larger divisions.
How to Grow Dendrobium Orchids From Seed
Seed propagation of orchids is not recommended, since it requires carefully controlled conditions and laboratory precision. In the wild, orchid seeds germinate through a complex symbiotic relationship with soil fungi, and duplicating this process artificially is tricky and prone to failure when attempted by amateurs. Thus, propagation is usually done by division (see above), a much easier method.
Potting and Repotting Dendrobium Orchids
Dendrobiums grow well in any well-draining container filled with commercial orchid potting mix, which is usually a bark-based medium. Repotting is usually needed every two to three years and is best done in the spring. Repotting is needed if the plant outgrows its pot, or if the plant has broken down the potting mix. Choose a pot large enough to accept four to six new canes, then slide the plant out of its old pot, rinse off the root ball, and plant in the new pot with fresh bark-based potting mix, spreading out the roots as you fill the pot.
Overwintering
Proper overwintering strategy can vary somewhat depending on species, but generally speaking, dendrobiums should be given a cooler, drier, rest period during the winter. Three or four weeks spent at 55 degrees Fahrenheit is often ideal, before returning them to the normal pattern of 60- to 65-degree nights and 75- to 85-degree days.
Common Pests & Plant Diseases
Mealybugs are the most common pest for dendrobium orchids, often hiding in the junction where leaves meet the canes. A good treatment is to spray with a homemade concoction consisting of equal parts water and rubbing alcohol, with a few drops of dish soap added. Large infestations may require spraying with a commercial pesticide formulated for houseplants. Diseases are not common with dendrobiums, but excessive watering may cause root rot. Petal blight, a fungal disease, can sometimes cause spotting on the flower petals. Affected blossoms should be removed.
How to Get Dendrobium Orchids to Bloom
For most types of dendrobium orchids, the long-lasting sprays of flowers remain in bloom for roughly six to eight weeks, and they can make excellent cut flowers. Spring and summer is the most common bloom season, though in optimal conditions, some types might bloom multiple times per year. If blooming seems suboptimal, try providing your orchid with more light. Improper temperatures can also cause orchids to be shy about blooming. These plants also need regular feeding during their active growing season. Getting dendrobium orchids to rebloom usually depends on giving them a rest period with lower temperatures—three to four weeks at 55 degrees Fahrenheit—and less water. This is not true of all species, however, so do some research on your specific dendrobium orchid.
Common Problems With Dendrobium Orchids
Dendrobiums are regarded as one of the easier orchids to grow, but you may run across these issues:
Yellowing, Spotted Leaves
Too much water can cause yellowing leaves, but with some species that are deciduous, it is natural for leaves to develop spots and turn yellow just before they are shed for the winter.
Burned Leaves
Browned edges on leaves can be caused by too much fertilizer or by growing medium that has become saturated with salts and minerals from tap water. Most likely, though, is sun scald caused by too much exposure to direct sunlight. If these plants are kept in south- or west-facing windows, it is a good idea to use a sheer white curtain during the summer months to diffuse the sunlight. Dendrobium orchids will tolerate partial shade and some direct sun, but bright indirect light is better. Low humidity can also cause leaves to dry up and turn brown.
