Tropical Gardening: Welcome spring with colorful azaleas, hydrangeas

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Before going on about azaleas, there is a correction to last week’s article.


Before going on about azaleas, there is a correction to last week’s article.

Jeff Marcus will be giving a program about the palms of Borneo on Friday, April 29, not in May. The meeting will be at 7 p.m. at the University of Hawaii at Hilo campus, Room 100. For more information, check out the Hawaii Island Palm Society website.

Now, with longer days, most folks are already getting chronic “Hawaiian spring fever.” This means getting close to nature with plants.

Hydrangeas are coming on the market with blue, pink or white flowers. They are a popular gift for Mother’s Day, which is only three weeks away, and seldom available during other times of year. Hydrangeas generally grow in cool, wet areas such as Volcano, but can be grown almost anywhere if given enough moisture and shade in sunny locations.

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. This spring, the plants also are available as potted house plants at our local garden shops and nurseries.

If you are looking for some spring color to perk up your home or garden, the azalea is a natural. Like hydrangeas, azaleas also make great gifts for Mother’s Day. In fact, they are the perfect gift just about anytime, since living gifts are gifts of aloha.

If you’re not quite sure about azaleas and you want to know what you are buying, here are a few tips to remember.

Azaleas are a part of a small but widely distributed family found in many parts of the world. They are usually found in cool, moist regions such as the Pacific Northwest and the Himalayas. Some species are even found on high mountains such as Kinabalu in Borneo.

Azaleas are actually rhododendrons. Many of this group are adapted to temperate regions, but some found Hawaii a good place to live.

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

Azaleas are slow growing in Hawaii. A good specimen 6 to 8 inches tall takes at least two years to reach the market. They are not easily grown from cuttings. That is why a gift of an azalea is something special.

Once you buy your living spring bouquet, they are easy to care for if you follow a few simple rules.

Azalea 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, wash them off with water. This will discourage insect and mite buildup.

The proper watering of plants is more important than giving them a bath. In general, plants require a thorough soaking at least once a week. In warmer temperatures or air conditioning, plants might require more water.

Applying too little moisture can allow the soil in the bottom of the container to dry out, causing the plant to wilt or die. On the other hand, keeping the plant roots soggy will also cause injury. Make sure the pot has sufficient drainage.

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

Like people, azaleas like their food served at regular intervals. Special acid azalea fertilizers are available. The best suggestion of feeding is to follow the directions on the plant food container. Since azaleas 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 can 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.

Remember, azaleas require an acidic 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 high in calcium. Avoid planting them in concrete containers, near sidewalks or concrete foundations since these contain calcium and will cause nutrient deficiencies.


If you want to learn more about the azalea/rhododendron family, visit the Panaewa Zoo in Hilo. The zoo has a great collection of vireya, or tropical rhododendrons, to view. You can also visit the new tigers and lots of interesting animal life from all over the world.

This information is supplied by the University of Hawaii College of Tropical Agriculture and Human Resources. For further information about gardening and landscaping, contact one of our master gardeners at 322-4892 in Kona or 981-5199 in Hilo.

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