Hawai'i Gardens
Some rhododendrons love warm climes
Rhododendrons and azaleas are much-loved garden plants, especially for gardeners in temperate climates. Many Hawai'i gardeners try to grow them in the garden or to nurture those lovely flowering potted ones they were given. Often, however, the plants don't look very good; they may even die. But IT'S NOT YOUR FAULT! It happens because these plants like cooler climes than many of us can give them.
Heidi Bornhorst • The Honolulu Advertiser
Happily, there are many lovely and colorful tropical rhododendrons that like warm climates, and local growers and hybridizers have been working to figure out how to grow them here. You can see some from a Big Island grower at the upcoming Foster Botanical Garden spring plant sale May 12. The growers will bring about 500 plants of 10 different hybrids to the sale.
Tropical rhododendrons can make a colorful display.
The tropical species and hybrids are called vireya rhododendrons. There are two main species that do well in Hawai'i gardens and that make good hybrids: Rhododendron vireya and R. Maddenii.
Vireyas are native to the broad area of southeastern Asian tropics with many species found in Indonesia, Borneo, Thailand and the Philippines. Interest in growing these spectacular plants is relatively recent. The Hawai'i Chapter of the American Rhododendron Society, centered in Hilo, already has more than 90 members.
Vireya rhododendrons like moisture. The plants on sale May 12 were grown in a nursery that is only a couple of hundred feet above sea level, and there are vireya collections from pali-side gardens on the Hamakua coast and even dry Kawaihae. On O'ahu, there are vireya growers in Kane'ohe, Mililani, Wahiawa and on Tantalus.
The flower colors range from white to light pink, dark pink to orange, reds and bicolors. There are some striking golden yellow forms. The leaves are also variable. Some are good in hanging baskets. Some are fragrant. Marie McDonald of lei-making fame is researching how they are best used in lei. Their success as cut flowers is being tested.
The hybrids are grown from cuttings. They need excellent drainage and root aeration. They like a rich organic soil and top dressing with mulch, so they do well in pots or in raised beds in light shade in your garden. They like regular watering and light doses of fertilizer. Their needs are similar to epiphytic orchids: good drainage and air circulation. Flowering may be off-and-on all year round, heaviest in the winter. You can pinch them back to encourage more flowers.
Some members of the rhododendron society will be on hand to answer your questions, and there will be two 40-minute demonstration classes.
If you are looking for the perfect Mother's Day gift, these lovely plants could be just the thing.
Heidi Bornhorst is director of Honolulu's botanical gardens.
