Until D. Spring Dream 'Apollon' was hybridized, nobile dendrobiums were difficult to bring into bloom in the low desert because they required cooler temperatures to initiate the bloom cycle. D. Spring Dream tolerates warmer temperatures and can bloom two or three times during a year. Many nobile hybrids still bloom best when they experience winter temperatures of about 40 degrees F. If daytime temperatures can be maintained at 62-64 degrees F as soon as buds appear, nobile hybrids will flower between January and April. 

Dendrobium nobile (the species) is native to Burma, India, Thailand, and Indochina. It grows on trees from lowlands up to 4000 feet in the highlands of the Himalayas. The blooms resemble cattleya flowers, and the plants require about the same level of light that a cattleya requires to bloom.

Optimum light/water: If the growth of leaves and stems is weak, move the plant to a higher light location. After the new growth hardens and matures, the plants will "rest" before the bloom cycle is initiated. During the resting phase, water the plant sparingly - just enough to keep growths from shriveling and do not fertilize again until after the end of the bloom cycle. 

Fertilization: Reluctance of nobile dendrobiums to flower in the low desert is generally attributed to improper fertilization practices - too much nitrogen given to the plant. Use a low nitrogen fertilizer after the bloom cycle - until August. Nobile dendrobiums should not be fertilized after August. Temperature: Canes or pseudobulbs which grew from spring through summer and matured in the fall, require approximately one month of night temperatures of about 50 degrees F to initiate the bloom cycle. At night, plants may be set outside in a protected area. 

Potting medium: Fir bark, sphagnum moss, and/or chopped coconut fiber can be used. A slightly acidic medium (pH 5) which drains well but still retains some moisture is ideal. For media that drain well, plastic pots are recommended. 

Appropriate pot sizes: For a small plant up to 3" tall, a 2-1/2" pot is sufficient; for a plant 5" tall, a 3" pot is adequate; and for a plant 10" tall, a 4" pot is appropriate. 

Air circulation: If air circulation is inadequate, especially during the bloom cycle, buds will be damaged and could be sparse in number. 

Repotting: Repot plants only after blooms have faded and only when night temperatures remain above 55 degrees F. Remove any decomposed potting medium and dead roots. Be careful not to damage live roots. Plants with more than 7 or 8 canes can be divided, but if no healthy canes are removed, a specimen plant can develop. If plants with only 4 or 5 canes are divided, the following year's growth will not be strong. Repotting small or medium size plants that have finished flowering should be done only when the pot has become too small to support the height of the canes. The best time for repotting is when new growths are about 4-6" tall. Plants should not be repotted when no new shoots are growing or when the plant has stopped growing. ___________________________________________________________________________________

Prepared by Wilella Stimell, Orchid Society of Arizona, 8/29,99