Many orchid species are epiphytes, or “air plants,” meaning they naturally grow attached to the surface of other plants, typically trees, in tropical and subtropical environments. This growth habit allows them to access better light conditions in the forest canopy and ensures excellent air circulation around their roots. Mounting an orchid onto a tree mimics its native habitat, offering a visually stunning display and promoting natural growth. Epiphytic orchids are not parasitic; they use the tree only for physical support. Their thick, fleshy aerial roots are covered in velamen, a spongy layer designed to quickly absorb water and nutrients from rain and organic debris.
Choosing Suitable Orchids and Host Surfaces
Selecting the correct orchid species and host tree is foundational to success, as the wrong pairing can prevent root attachment or harm the plant. Orchids that are naturally epiphytic and possess a robust root system are the best candidates for mounting. Genera such as Cattleya, Dendrobium, Vanda, and some Phalaenopsis hybrids adapt particularly well. It is helpful to select an orchid that is actively growing and producing new roots, as this increases the plant’s chance of quickly establishing an anchor on the host tree.
The host tree must offer a non-toxic, rough surface that allows the orchid’s roots to grip securely. Hardwood trees with deeply fissured bark, like oaks, citrus, or rough-barked palms, provide a stable, long-lasting anchor point. Positioning the orchid on the north or east side of a tree trunk or on a horizontal branch beneath the canopy can provide the bright, filtered light most species prefer, while offering protection from intense afternoon sun. Certain trees must be avoided, including those that shed bark frequently, like some sycamores, or those that produce toxic sap or tannins, such as black walnut, eucalyptus, and aromatic cedars. These substances can inhibit the orchid’s delicate root tips, preventing attachment and establishment.
The Physical Mounting Process
Before securing the orchid, prepare it by gently removing all old potting media from its root system. Soaking the orchid’s roots in water makes them more pliable and reduces the risk of breakage. Any soft, mushy, or completely desiccated roots should be trimmed away using a sterilized cutting tool, leaving only the firm, healthy roots.
The key to positioning is ensuring the orchid’s new growth is directed outward, away from the bark, and that the base of the plant is pressed firmly against the host surface. For sympodial orchids, like Cattleya, the newest growth should face toward the tree so that subsequent growths can grow up the trunk or branch. A small, thin pad of moistened sphagnum moss or coconut fiber can be placed between the roots and the bark to provide a temporary moisture reservoir, but excessive moss should be avoided to prevent rot.
To secure the orchid, use a non-toxic material like biodegradable cotton twine, natural fiber string, or plastic-coated wire, avoiding any material that could girdle the plant or the tree. The tie should be wrapped snugly around the roots and the bark, ensuring the orchid cannot shift or wobble, which would damage tender new root tips. The objective is temporary support until the new aerial roots have firmly attached to the tree bark. Once the new roots have visibly attached and spread across the bark, the temporary ties can be carefully removed to prevent them from cutting into the expanding plant tissues.
Ongoing Care for Established Tree-Mounted Orchids
Care for a mounted orchid changes significantly from a potted one because the roots are exposed to the open air, causing them to dry out faster. Immediately after mounting, the orchid requires frequent watering to encourage root establishment, often daily for the first two to four weeks. After the initial establishment period, daily watering or drenching three to five times per week may be necessary, depending on the local climate and humidity levels.
Fertilization must be adjusted to a dilute, frequent regimen, typically using a balanced orchid fertilizer mixed at one-quarter to one-eighth the strength recommended for potted plants. Since there is no potting medium to hold nutrients, the fertilizer should be applied with the water, often through foliar feeding or drenching the entire root mass. This frequent, light feeding prevents the buildup of fertilizer salts, which can burn the exposed root tips.
Seasonal considerations are important for the long-term survival of the mounted orchid, particularly concerning temperature and light. While many common mounted species tolerate a range of temperatures, protection from frost is required, which may involve covering the plant with frost cloth or temporarily moving small branches to a sheltered location. Monitoring the sunlight is important; if the host tree loses its leaves in the winter, the orchid may be exposed to much higher light levels than it can tolerate, necessitating temporary shade or relocation during the dormant season.