Essentially, these orchids needs regular water and orchid fertilizer all spring and summer, with very limited water and no fertilizer after October. I put little signs on my orchids to remind myself of this. "Don't water me". It also helps to have the plants in a cooler location for a month in the fall season. Mine are in a heated greenhouse, where temperatures drop to 14 degrees C (57 degrees F) at night. I previously have had success placing them near a large and poorly-sealed window in an older house. A bay window or sunroom might work for this purpose.
Within a few months, small round buds appear along the length of the stems. If you fertilize at this point, the buds grow into tiny plants, complete with roots, if you leave them long enough. These are keikis and can sliced off the mother plant and be potted up as new plants.
|Keiki on my Dendrobium|
|Dendrobium nobile "Angel Smile" in bloom, February 23, 2016|
This orchid likes bright light and tolerates cool to quite warm temperatures in the greenhouse. I give mine supplemental pinkish LED light in the greenhouse (which makes up for our short winter days). However, I have grown these before in a bright sunny indoor spot too, so you don't need a greenhouse. Generally, I think this orchid is quite easy to grow. It is a pity they are not often sold at local garden stores.
This website also has more detailed care instructions: http://www.akatsukaorchid.com/store/pg/29-Dendrobium-Nobile-Care.aspx