Culture: This plant will grow vegetatively at any temperature, any light, and any kind of watering and feeding- but if one wishes it to bloom to its fullest potential, then it MUST be grown cool (min night temp in autumn and winter below 50F); maximum light; lots of water when growing; and lots of food, but never in a high Nitrogen ratio. Dendrobium kingianum grows normally down to 35F (will tolerate temps down to 29F), so I put mine outside in April (Boston area), in full east sun; and it comes back inside in Nov. After blooming, all keikis are removed, as well as old flower spikes, and the new developing keikis are left on as they will remain uniform in size and will increase the amount of flowers.
All dendrobiums will produce keikis, however kingianum varies from clone to clone, and within reason this has nothing to do with culture. This is in contrast to nobiles, which make excessive keikis with too much N, or not enough sunshine. Certain clones, such as 'Ruth' AM/AOS, and 'Roy' AD/AOC/QOS-HCC/AOS, produce multiple keikis and if these are not removed after blooming the keikis make keikis, and these make keikis and soon there is a veritable weed patch. 'Karl Marx' rarely makes keikis and when it does they are small, and on removing may behave like seedlings out of flask and take 3 to 5 years to bloom; whereas the usual keiki after removal can be planted and will make a new growth, perhaps a keiki, and all will usually bloom the following season.
The pot is watered enough to keep it moist, and during hot weather this may be every day. It is fed 100ppm of N/gal/wk, in a low N ratio, as 9-30-25. All are potted in a bark mix, and in plastic, Azalea type pots. The plant is brought inside in Nov, to a cool house (min night temp of 46F) and water is withheld until buds start to develop (6-8 weeks). At this time I spray the leaves once or twice a week, and when the buds can be recognized I resume watering the pot, once a week, and after the flowers open I resume watering to keep the plant evenly moist. I do not fertilize until the flowers are open. I have learned by trial and error that some clones can be watered the entire year, and bloom well ('Ruth' and 'Roy'); others behave as the book advises and must be dried out if they are to bloom; and this varies in both natural and outcrosses. If the conditions can be met for the culture of this plant I believe it should be in every collection.