The Dendrobium Aggregatum is an epiphyte, that is found from North-East India through Indochina and Thailand. Plants have been found at altitudes of above 500 meters but can also be grown in warmer to intermediate conditions. The plant is open to a variety of different situations as long as it gets plenty of light, water, and a winter rest.
The Den. Aggregatum needs a lot of diffused sunlight (about 35-50% shade). Most will grow well under the same light conditions as most cattleyas. When pseudobulbs turn a reddish color, the plant is receiving the most light it can handle and should be left in place unless it starts to sunburn. During the plant's winter rest, the amount of sunlight should be maintained (do not give it less light).
In their native habitat, these orchids experience mild to warm daytime temperatures in spring and summer, and generally cooler temperatures in the winter. This type of plant can grow in a wide range of temperatures, daytime temps can be in the 70's-80's. But it is not unusual for this type of dendrobium to handle temps in the summer months in the high 90's if the weather is humid). The winter night temperatures range from about 45°F to about 60°F.
The watering may be the most crucial element to success with these orchids. Their native conditions are fairly wet during the late spring, summer and early fall. Rainfall can be quite heavy for a few months, but it tapers off in the late fall, and winter months are fairly dry. Water the plants regularly when they are actively growing; mounted plants can be watered daily if air circulation is good. When the new pseudobulbs have matured in the fall, gradually reduce watering, and allow the plant to dry between watering.
These dendrobiums benefit from regular feeding when they’re actively growing. Any balanced, water-soluble fertilizer can be used, diluted according to package directions. We feed once a week during the active growing season. Reduce feeding in the fall and eliminate it completely when the plants are resting in the winter. Resume feeding when the plant begins to grow again, or when it begins to initiate flower spikes.
Den. Aggregatum requires a winter rest period. For a few months (Nov-Jan), the plant should be exposed to 50-60-degree temperatures at night with slightly warmer days. Watering should be gradually withdrawn and fertilizing completely stopped. Plants should be watered very sparingly throughout the rest period if the pseudobulbs show extensive shriveling. Some shrinkage should not be alarming, and plants may be partially deciduous. Sun exposure should remain the same from the growth period through the rest period in order to ensure spring blooms and growth.