The Plant Hardiness Zone for the Dendrobium Orchids

Temperature

• Known to be either deciduous or evergreen, depending on the cultivar, dendrobiums are accustomed to a tropical habitat because they are originally found in the Eastern Hemisphere. In general, these perennials prefer nighttime temperatures between 45 and 65 degrees Fahrenheit, while daytime temperatures can range from 70 to 90 degrees. Orchids are especially vulnerable to wide temperature swings during blossoming; buds and open flowers actually fall from the plant if a cold weather front moves in. Although you may not live in a tropical region, growing dendrobiums indoors is a close approximation of their preferred habitat.

Shade Consideration

• Although they enjoy warm conditions, your dendrobiums should not be in direct sunlight. They naturally grow on trees, their roots grasping the limbs as flower stems hang down. Typically, their sunlight exposure should only be limited to the morning with ample afternoon shade, or approximately 50 percent shade each day. This shading strategy allows the dendrobiums to direct their energy into water and nutrient absorption as the roots remain exposed in the air. Excessive sunlight causes heat stress and possible dieback or bud drop. In contrast, heavy shade contributes to low photosynthesis energy and failed flowering.

Moisture

• Dendrobiums do not have a true dormant stage, but autumn and early winter are commonly dry times in their natural habitat. Allow your dendrobiums to dry slightly during this period as foliage growth slows and root development increases -- your plant is gathering energy for next season's blossoms. As spring and summer arrive, water your dendobiums more to simulate natural rains, but do not waterlog the roots because rot sets in quickly. Preferring humidity levels above 50 percent, provide some moist, surrounding air by placing water bowls around the plant. The water slowly evaporates around the dendrobiums, especially for indoor plants, as the roots take in the moisture.

Container Environment

• Although dendrobiums are ephiphytes, growing on other plants in the wild, they also acclimate to containers well as they simulate their preferred hardiness zones. Thriving in a root-bound state, replace the orchids' favorite bark growth medium every year. New orchid mediums do not have a decayed and compacted consistency which allows the roots to find air pockets as they absorb water molecules in the air.