San José, Costa Rica, since 1956

Azalea a Gorgeous Border Shrub

LOOKING for a border shrub with gorgeous flowers in all shades of pastel pink, orange, white or red? Azaleas may fit the bill. Azaleas are alive and well in Costa Rica, particularly in the cooler regions of the country, and most leading nurseries offer varieties of these flowering bushes.Many of the Rhododendron species are from Asia. Indian azalea (R. simsii), Japanese kurume azalea (R. obtusum) and other, Chinese varieties were grown in Asia for millennia before they were introduced into the tropical Americas. However, there are species native to the Western Hemisphere, such as Florida’s R. austrinum, with its masses of yellow-orange pastel blooms, and R. calendulaceum, or flame azalea, which should not be overlooked and whose blossoms are as exquisite as the others.Members of the Ericaceae family, these flowering shrubs are related to mountain laurel and blueberry. They grow best in acid soils rich in organic matter or humus, and require full sun or partial shade. They are not tolerant to salt conditions near the coastal areas. If these conditions aren’t met, azaleas tend to have stunted growth and poor flowering.THE other day I saw a potted azalea on an office patio. The poor thing was planted directly in red clay soil and looked like a bonsai, with only one little flower. It was a brave attempt on the plant’s part, but poor planning by the gardener.Plant your newly acquired azaleas with plenty of compost fertilizer; do not add limestone or ashes. Leaf mulch or wood chipsare other good ingredients for azaleas. Shrubs should be planted1.5 meters apart, along borders or foundation plantings. Some gardeners opt for single standing specimens.You can also propagate your own azalea plants from woody stem cuttings of mature shrubs. The 15-centimeter-long cuttings can be started in flats or in separate nursery bags or pots with prepared potting soil. Keep them well watered and in a shady area of the greenhouse until they begin to form new leaves. After that, simply move them into full sun and transplant to permanent sites when they look hardy.ONCE your shrubs are well established, prevent lawn grasses from invading their root systems, mulching with dried leaves or other high-fiber mulch. During the heavy rains, you may want to pull the mulch back to avoid drowning the root system, as we do with many of our plants. Azaleas should be watered faithfully during the dry season. You can prune these shrubs once a year to keep them compact in shape. Annual fertilization with more aged compost and leaf mold is also recommended.Mineral deficiencies can cause leaf diseases and flower spotting, as well as insect attacks. Your can foliar-feed the plant’s leaves with seaweed extract or citrus seed-oil extract to keep them healthy and blooming.In Florida, azaleas bloom in the late winter or early spring, when there are festivals to celebrate their beauty. However, in Costa Rica, I’ve observed them blooming most of the year. The photo of the Indian azalea shown here was taken in August. Could it be the plants are happier here, or does it have to do with the daylight hours? Or both? For info on tropical gardening, visit, or e-mail questions to

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