If you were to visit the humid tropics of Asia, Central and South America you would be amazed at all the plants that grow on the branches of trees and even on rocks with no soil. We do have lichens, mosses and even ferns that have evolved here to festoon rainforest and cloud forest trees, but there are few compared to the rest of the tropical world.
Those growing on trees are referred to as epiphytes. Those growing on rocks are lithophytes. When you think of it, much of the vegetation growing on our young lava lands fit in to this category. For example, a young ohia and hapu‘u forests where there is no soil can be considered terrestrial and lithophytic as well.
This group of unusual tropicals referred to as epiphytes and lithophytes use their roots to attach. The little nutrients and moisture they require are supplied by debris and precipitation they capture. The group includes many ferns, orchids, bromeliads and even some cacti. Although epiphytes grow attached to shrubs and trees, they are not parasites, since they do not take their nutrients from the plants on which they grow. Air plants have some of the most beautiful flowers and unique foliage in the plant kingdom. They generally require less care than most other ornamentals. Our tropical climate is ideal for air plants that are virtually impossible to grow outdoors anywhere else in the United States except in the warmest parts of California, the Gulf Coast and Florida. Here, many grow with almost no care.
Orchids and bromeliads are probably the most well known of the epiphytes. Many species have been introduced. Local nurseries have them available in abundance. If you have a tree or lanai in which to hang pots, you can have flowers the year round. All it takes is a little common sense, water and fertilizer. In fact over watering or over fertilizing is the most common cause of their demise. When buying orchids and bromeliads, it is important to get healthy plants. Ask the grower or nurserymen about the particular species and its care. When grown in containers, they will require repotting every 2 or 3 years. To avoid the problem of repotting, many gardeners remove the plants from the pot and attach them to the branches of a tree. Rough barked trees like ohia, paperbark, monkeypod, calabash and other rough barked trees are usually best.
The epiphytic ferns and cacti may be also grown in pots or on trees. The secret of success is to be sure they have good drainage. Overwatering is the fastest way to kill them. Fertilize lightly every 3 months to keep plants in active growth. But if plants are attached to trees, this is not required. Several brands of orchid fertilizer are available. They are satisfactory for other air plants as well. These are specially formulated and when used according to directions will give excellent results. Disease and insect problems are few. If they do occur, our local garden supply dealers have fungicides and insecticides to quickly control the situation.
Give the air plants a try in your garden. Start with easy types such as bromeliads, like Tillandias, Billbergias, and Aechmeas. Staghorn and Resurrection Ferns are easy. Dendrobium, Epidendrum and Oncidium orchids will thrive on a minimum of care. From there, move up to the more exotic Cattleya and Phaelaenopsis orchids. There are even epiphytic tropical Vireya Rhododendron, Medinella and Clusia. The latter may start as an epiphyte but ultimately strangles the support tree as would a banyan or Schefflera. Local nurserymen can give you quite a few ideas on the types to grow and ways to grow them.
Some folks worry that insects may breed in the center of bromeliads holding water. That is why natural insect control with lizards, amphibians, frogs, toads and birds make good gardening sense. It also makes the garden more interesting. Anole lizards, chameleons and geckos, add to the magic of our gardens. Many common birds feed on insects as well. To keep your bromeliads free of mosquitos, use a biological control that kills only the larvae. The tongue twister name is Bacillus thuringiensis subspecies israelensis. The easiest is the granule form and sprinkling a few grains in the center every few weeks to eliminate those pesky guys.
Norman Bezona is professor emeritus, University of Hawaii College of Tropical Agriculture and Human Resources.
