Vanda orchids are known for their stunning, colorful blooms. Unlike many common houseplants, these orchids are epiphytes, meaning they naturally grow attached to trees or rocks rather than in soil. This unique growing habit makes the root system the most distinctive feature of the plant, requiring a specific approach to care. The long, trailing aerial roots are specially adapted to rapidly absorb water and nutrients from the environment.
The Unique Anatomy of Vanda Roots
The physical structure of Vanda roots is highly specialized for an aerial existence in a humid, tropical environment. The most prominent feature is the velamen, a thick, spongy, multi-layered epidermis that encases the inner root tissue. This velamen is composed of dead, empty cells that function much like a sponge for rapid absorption of atmospheric moisture, dew, and rainwater.
Once saturated, the velamen retains water and protects the inner root cells from desiccation. Separating the velamen from the cortex is the exodermis, which contains specialized “passage cells” that control the movement of absorbed water into the plant’s core. This entire structure allows the Vanda to manage quick wet-dry cycles, necessary in its natural habitat.
Essential Care for Aerial Root Systems
Vanda orchids are adapted to quick wet-dry cycles, so their watering needs are frequent and substantial. The preferred method for bare-root Vanda is “dunking,” which involves submerging the entire root system in lukewarm water for 20 to 30 minutes. This allows the velamen to fully saturate and absorb maximum moisture. Depending on the environment, this soaking may need to be performed daily or at least two to three times per week.
A high-pressure misting or spraying for a minute or more is another common approach. This ensures the silvery-white roots turn green, indicating full saturation. Watering should always be done in the morning to allow the roots to dry completely before nightfall. Allowing the roots to remain wet overnight is a common cause of fungal issues and rot.
High air circulation around the roots is necessary for Vanda survival, supporting rapid drying after watering. Stagnant air encourages the proliferation of harmful bacteria and fungi. Humidity is also a major factor, with levels of 65% to 80% being ideal, as higher ambient moisture keeps the velamen supple and ready for absorption.
Identifying Root Health and Distress
Observing the aerial roots provides a visual indicator of the plant’s overall health and watering schedule. Healthy Vanda roots are firm and plump, changing appearance distinctly when wet versus dry. When dry, the velamen gives the roots a silvery-white or grayish color due to trapped air.
After successful watering, healthy roots change color to bright green, indicating the velamen is saturated and the underlying chlorophyll is visible. The growing tips should also be a bright, active green color, signaling ongoing growth.
Distress is evident through changes in root texture and color. Desiccation, or chronic under-watering, results in shriveled, thin, and brittle roots that fail to plump up or turn green. Root rot, caused by overwatering or poor air movement, manifests as mushy, dark brown, or black roots. If the outer velamen slips off easily, the root is dead and should be removed with a sterile tool to prevent decay.
Mounting and Housing Options
Traditional potting mix is generally unsuitable for Vanda orchids, as it does not allow the roots to experience the necessary quick drying cycle. Many large Vanda specimens are grown in bare-root culture, suspended in the air with their roots completely exposed, a method primarily used in high-humidity greenhouse settings.
A popular housing solution for home growers is the use of slatted teak or plastic baskets. These baskets provide structural support while maximizing air exposure around the root mass, which still hangs freely below. Mounting the orchid onto a hard piece of material, such as cork bark or a slab of durable wood like cypress or oak, is another excellent option that mimics the plant’s natural growth habit.
If a Vanda must be potted, such as a smaller plant or one needing more moisture retention, the container must be filled with a very coarse, fast-draining medium. This specialized media might include large chunks of charcoal, bark, or lava rock, specifically chosen to create maximum air pockets and prevent moisture from clinging to the roots for too long.