Hybrids derived from the species Dendrobium nobile have been very popular for more than a hundred years. Their long running popularity springs from their profuse show of long lasting brightly colored flowers, which bloom along their stems in late winter and early spring. The species itself is also very popular because it regularly flowers freely and lasts for a long time as cutflower. These traits have been passed along to its progeny. Dendrobium nobile and its hybrids are very easy to grow, if a couple of specific cultural requirements are met.
As the new growths begins in the spring, increase water and fertilizer frequency. During the active growing period of spring and summer Dendrobium nobile prefers reduced light, increased water, and fertilizer every two weeks (1/2 teaspoon per gallon of urea free water soluble fertilizer ). As the plants mature in the fall, cultural needs change drastically. Now brighter light, cooler temperatures, and no fertilizer will help to initiate flower buds. Water normally so that the bulbs do not shrivel. Buds will appear when the night temperatures drop to 55 or lower and the growths have fully matured. This is usually in November to December in the northern US, and January to February in the southern US. Blooms will follow in about two months after the cooling period.
When these plants are grown inside, they should be placed outside in the fall to benefit from the cooler temperatures at night. In the northern US, they should brought inside, when the night temperatures are consistently below 45F. In the southern US, they should be brough inside before the onset of freezing weather. They should kept in a relatively cool location (such as an unheated room or an enclosed porch) until buds start to form.
Dendrobium nobile and their hybrids enjoy being root bound, so never overpot the plants. They do very well in small pots for their root mass. Clay pots does them well. Many growers use regular seedling bark mixture or osmunda for a potting media; however, some growers also use long-fibered sphagnum moss. Dendrobium nobile can also be grown mounted, or in baskets, but watering must be increased.
If keikis or off-shoot plantlets form along the stems, that is usually a sign of too much fertilizer and/or too warm night temperatures. These keikeis may be potted as new plants after they have formed roots of at leat 3 or 4 inches. If plants produce all keikis and no blooms, definite culture changes are in order, such as longer cooling period in the fall and reduction in fertilizer amounts.