From the perspective of the orchid plant, mounting on a slab is not a novel horticultural technique; it is a return to its natural evolutionary state. Most ornamental orchids are epiphytes, meaning they grow upon other plants (typically tree branches) in their native tropical habitats. Their roots are not adapted to being buried in dense, moisture-retentive soil. Instead, they are aerial organs designed to cling to rough bark, absorb water and nutrients from humid air and rainfall, and perform photosynthesis. A slab mimics the texture, stability, and air flow of a tree branch, providing the orchid with an environment that aligns with its fundamental biological needs, thereby reducing plant stress and promoting natural growth patterns.
The choice of slab is critical as it becomes the orchid's home. From the plant's viewpoint, the ideal slab is porous, moisture-retentive yet free-draining, and chemically inert. Tree fern plaques are excellent because they hold moisture and provide a rough texture for root attachment. Cork bark is another superb choice, offering excellent drainage and a natural appearance. Cedar and manzanita wood are durable options. The plant requires a surface that its velamen-covered roots (the spongy, white outer layer) can easily grip onto. The slab must not rot quickly or leach harmful resins, such as those from pine or cedar, which could damage the orchid's sensitive root system.
The physical act of mounting must be done with care to avoid damaging the plant's structures. First, the orchid is gently removed from its old pot, and old potting media is carefully teased away from the roots. Soaking the roots briefly can make them more pliable and less prone to breakage. The plant is then positioned on the slab so that its base, where the newest growth emerges, is near the top, allowing for future growth to cascade naturally. A key biological consideration is to not bury any part of the plant; the rhizome and base must remain exposed to air to prevent rot. The roots are then gently spread across the slab's surface.
To establish itself, the orchid needs to be firmly anchored until its roots naturally adhere to the slab. This is typically done using a non-degradable material like fishing line, plastic-coated wire, or nylon stockings. These materials are strong, flexible, and won't introduce pathogens as they break down. The plant should be tied snugly but not so tightly that it cuts into the rhizome or constricts root growth. Immediately after mounting, the entire assemblage—slab and orchid—should be soaked in water for 10-20 minutes. This rehydrates the plant after the stressful process and saturates the slab. The mounted orchid should then be placed in a shaded, humid location with good air circulation for several weeks to recover, mimicking the protective canopy of its natural habitat before it ventures into brighter light.
Life on a slab requires a different watering regimen than potted culture. The orchid's roots will dry out much faster, which is healthy and prevents rot, but it means the plant will need more frequent hydration. In the plant's terms, it expects frequent, heavy rains followed by periods of rapid drying. This typically translates to daily misting or soaking in warmer weather, potentially less in cooler, humid conditions. Fertilization must also be adjusted. A weak, balanced fertilizer should be applied regularly (e.g., weekly or bi-weekly) since there is no organic media to hold nutrients. The plant is adapted to absorb nutrients quickly through its roots and leaves when they are available, making frequent, dilute feeding the most effective strategy.
