Tropical Gardening: Tropical Vireya rhododendrons thrive in Hawaii

  • Courtesy of VOLTAIRE MOISE Tropical Vireya rhododendron form large shrubs when grown under ideal conditions such as Kaloko Mauka, Kona, and moist regions of East Hawaii. Colors range from white, yellow, orange and red. There are hundreds of species and hybrids.

Throughout the northwest U.S. and Japan, one of the highlights of spring is the mass blooming of azaleas and rhododendrons. In Hawaii, these attractive garden shrubs are popular in cool, mauka areas.

Now Vireya rhododendrons are becoming available throughout the year as more nurseries and gardeners are becoming aware of them.

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If you’re not quite sure about the tropical rhododendrons and how to grow them, then get acquainted with the experts by joining the Hawaii Chapter of the American Rhododendron Society. Because of the COVID-19 pandemic, the chapter is not having its regular meetings, but you can still get the regular newsletters and network with members individually. The members are great in sharing plants to try in your own garden.

Vireyas usually grow in cool, moist regions. Some species are even found on high mountains. But many are adapted to warm and moist temperate regions, and many have found Hawaii a good place to live, especially in forest areas protected from wind. Here, they can be grown in organic cinder and soil mixes, but if the conditions are just right they can grow on rocks or as epiphytes along with orchids, ferns and bromeliads.

Some species and varieties you will find on the market bloom in brilliant reds, whites, pinks, salmons and even mixes of white-pink and white-red.

Typical azalea relatives are slow- to moderate-growing in Hawaii. A good specimen 6-8 inches high takes at least two years to reach its prime flowering. These reach our local markets in early spring. They are not easily grown from cuttings. On the other hand, many Vireyas can be easily grown from cuttings and can become large shrubs or small trees. This family of flowering plants is extremely variable, but have certain characteristics in common.

When you buy a potted Vireya living bouquet, they are easy to care for if you follow a few simple rules.

Plants won’t tolerate a daily scrub down, but they will take on a healthy look with an occasional leaf washing. Dirty foliage is unattractive.

If the leaves get heavy with dust or sooty mold, wash them off with water. This will discourage insect and mite buildup. In general, plants require a thorough soaking at least once a week. In warmer temperatures, plants in containers might require more water. Make sure the pot has sufficient drainage.

When planted in the garden, they are much happier. Where rainfall is sufficient, they take almost no care. We have grown quite a few in Kaloko Mauka, and they are happy unless we have an extended dry period.

Azaleas and Vireyas grow well at temperatures between 60 and 70 degrees. Therefore, protect the plants from being broiled alive by direct sun and hot or windy areas. In cool mauka areas, they can be placed in sun.

Like people, they like their food served at regular intervals. Special acidic azalea fertilizers are available. The best suggestion of feeding is to follow the directions on the plant food container. Since they are slow growers, they should only need fertilizer once every two to three months.

Here are some tips for diagnosing plant troubles.

Brown tips or burned margins might mean you applied too much fertilizer, you let the plant roots dry out or you let the plant become wind burned. Yellowing of leaves indicates overwatering, poor drainage or poor soil aeration. Small leaves suggest a tight or heavy soil mixture, lack of fertilizer or not enough moisture. Weak growth or light green color on otherwise healthy foliage indicates too much light, lack of fertilizer, root rot or poor root systems. Yellowing, wilting or soft growth means too much heat or root injury.

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Remember, azaleas and Vireyas require an acid-high organic soil. If you decide to plant them in the garden or repot them, give plants a mix high in peat moss. Make sure you don’t plant them in soils that are high in calcium. Avoid planting in concrete containers, near sidewalks or concrete foundations since these contain calcium and will cause nutrient deficiencies.

It is not always easy to find Vireya rhododendrons at local garden shops and nurseries. The best bet is to get acquainted with folks in the local chapter of the rhododendron society. You can connect with them by contacting Sherla Bertelmann at 966-9225. You can also check out their website at www.HawaiiVireyaARS.org for meeting dates and news.

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