Dendrobium orchids, a vast and diverse genus, exhibit a range of growth cycles, but many popular species and hybrids undergo a crucial physiological phase known as dormancy. This period is not a sign of illness but a natural, adaptive strategy for survival, triggered by environmental cues that signal the end of the active growing season and the approach of a less favorable time of year, typically a dry or cool season in their native habitats.
From the plant's perspective, dormancy is a period of energy conservation and redistribution. As daylight hours shorten and temperatures drop, the orchid's metabolic processes slow down significantly. The plant ceases producing new leaves and roots, halting vegetative growth. Its primary focus shifts from expansion to sustenance. Energy previously allocated for growth is now redirected and stored within its pseudobulbs—the thickened, water-storing stems. These pseudobulbs act as reservoirs, swelling with moisture and nutrients to sustain the plant through the impending period of environmental stress where water may be scarce. This is a calculated survival mechanism to endure conditions that would otherwise be fatal.
The orchid communicates its entry into dormancy through clear physical changes. The most obvious sign is the cessation of new growth; no new leaves, roots, or canes will emerge. Furthermore, the plant may begin to shed its leaves from the older pseudobulbs. This is a normal process of abscission, where the plant actively reabsorbs valuable nutrients and chlorophyll from the leaves before discarding them to reduce water loss through transpiration. The pseudobulbs themselves may appear slightly wrinkled or shriveled as the plant begins to consume their stored reserves, but they should remain firm to the touch.
To support the orchid's natural cycle, its care must change dramatically. The most critical adjustment is a severe reduction in watering. The plant's water requirements plummet as it is not actively growing and transpiring minimally. The growing medium should be allowed to become completely dry for a extended period between waterings, perhaps reduced to a light misting or sparse watering every few weeks. Fertilization must be stopped completely, as the dormant roots cannot absorb nutrients, and any salts present in fertilizer can damage them. The plant should be moved to a cooler location with temperatures often 10-15°F (5-8°C) lower than its summer growing conditions and given slightly less light, though it still requires bright, indirect exposure.
The dormancy period is broken by a consistent change in environmental conditions, most notably a gradual increase in temperature and day length. The plant senses these cues and prepares to break its rest. The first sign is often the emergence of new growth, typically flower spikes (inflorescence) or, subsequently, new vegetative growths (keikis or new canes) from the base of the plant. This is the signal to gradually resume regular care. Watering should be slowly increased as new roots develop, and fertilization can begin again at a diluted strength once the roots are actively growing.
