Vireya

Vireya are rhododendrons, semi-tropical rhododendrons. They grow mostly in the mountainous regions of Malaysia centered in and around the Equatorial zone including Indonesia, the Philippines, Borneo and Papua New Guinea. Of the 850 or so species that make up the genus Rhododendron, almost 300 are classified as vireya.

In their homelands, vireya can be found growing as epiphytes in the moss-encrusted lofts of tree branches, on rocks, or just growing as terrestrials, on the ground. They grow on the edges of forests and in open grasslands, seeking light. They are often the first plants to colonize areas where the original vegetation has been destroyed.

Vireya come in a variety of shapes and sizes ranging from dwarf mats at high altitudes to all sizes of shrubs, and even trees. Some have foliage that could be mistaken for pine needles; some have huge leaf blades a foot long with flowers to match. Their flowers are often fragrant and are the most colorful of all rhododendrons. Vibrant yellows and reds are common. Flower shapes vary from small, open cups to spidery clusters of long tubes.

On the Big Island, vireya hybrids exist in gardens from 4,000-foot elevation down to sea level. It helps to think of them as orchids, with similar needs such as drainage and good air circulation.

Vireya have very fine surface roots, as opposed to a tap root. The most important factor in planting is excellent drainage important. Vireya do not like soggy feet, as they can develop root rot. Raised beds or mound plantings work the best. Because vireya roots run close to the surface, they can heat up from the sun. Covering with several inches of coarse mulch will keep them cool.

Bright light helps to set buds as well as shortening stem internodes. Though vireya love light, dappled light is recommended especially during our peak summer heat. Planting vireya under hapu`u (tree ferns), or near other plantings will give some shade. This will help prevent leaf burn and faded out flowers. Though there are varieties that will take full sun, they do equally well under dappled light.

Pinching off new growth promotes more branching as will deheading the seedpods, which will put the energy back into new growth and bud development rather than into seed production. Fertilizing should be very light. Lacewing insects can be a problem leaving silver spots covering the leaves.

Vireya can be easily rooted from cuttings. Some vireya, depending on the variety, can take as long as a year to root, though the average time is closer to three months. Vireya can also be grown from seed. A single seed pod can contain as many as several hundred seeds. But it may take three to eight years, depending on the variety, before flowering begins, whereas from cuttings that time is cut in half.

In the past few years the number of vireya hybrids coming into the islands has greatly increased. One reason for this is the Hawai`i Chapter ARS. Last year more than 75 new varieties were brought in from Australia. Networking with others in California has also brought in new hybrids.

Information provided by Sherla Bertelmann and Richard Marques - owners of Pacific Island Nursery, a mail-order nursery located in Kea`au, specializing in vireya rhododendrons. They are members of the Hawai`i Chapter of the American Rhododendron Society. (See Credits & Links page).