An Improved Method of Air Layering Tropical Hardwoods for Forestry, Fruit, and Ornamental Nurseries

Air layering is a well established technique for the propagation of both woody and herbaceous plants.  Common components of a successful air layer include an actively growing plant, girdling of the stem, application of rooting hormone, and rooting medium held to the stem with plastic film or aluminum.  An improvement on the existing air layering arts has been developed that makes use of net bags filled with sphagnum moss to secure rooting medium to the stem. Development of this technique in Hawaii has been conducted primarily on the Rainbow Shower Tree (Cassia x nealiae cv. Wilhelmina Tenney), a sterile hybrid and the official shade tree of Honolulu. Under ideal growth conditions, woody branches with a diameter of up to 10–13 cm have been induced to produce a prolific mass of roots in 2–4 months.  Root development with this improved system is robust enough for direct field planting, thus skipping the nursery grow out phase.  Other species that have been successfully air layered with this technique include cacao (Theobroma cacao), mango (Mangifera indica), longan (Dimocarpus longan), Hawaiian Koa (Acacia koa), and Hong Kong Orchid Tree (Bauhinia blakeana).