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Norman Bezona Prof emeritus University of Hawaii College of Tropical Agriculture

Norman Bezona
Prof emeritus
University of Hawaii
College of Tropical Agriculture

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. This is a popular Mother’s Day gift and seldom available at other times of year. Hydrangeas generally grow in cool wet areas like Volcano, but may 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 are also 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.  It’s a great gift for Mother’s Day that is only three weeks away.  In fact, it’s perfect for a gift just about anytime, since living gifts are gifts of aloha. 

Hydrangeas are best in cool gardens of Volcano, Kaloko Mauka and upper Hilo but will grow almost anywhere when given sufficient moisture. Photo: Voltaire Moises

Hydrangeas are best in cool gardens of Volcano, Kaloko Mauka and upper Hilo but will grow almost anywhere when given sufficient moisture. Photo: Voltaire Moises

If you’re not quite sure about azaleas and you want to know what you are buying, then 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 like Kinabalu in Borneo.  Azaleas are actually rhododendrons.  Many of this group are adapted to temperate regions, but some have found Hawaii a good place to live.

Some of the 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 six to eight inches high 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.

Azaleas - possible in Hawaii at higher elevations

Azaleas – possible in Hawaii at higher elevations

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 may require more water.  Applying too little moisture may 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 wet 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 may 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 on diagnosing plant troubles.  Brown tips or burned margins may mean you’ve applied too much fertilizer, you’ve let the plant roots dry out, or you’ve let the plant become wind burned.  Yellowing of leaves indicates over watering, 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.

Vireya - The tropical rhododendron

Vireya – The tropical rhododendron

Remember, azaleas require an acid 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. Also remember, azaleas should not be planted near the ocean or in hot, dry or windy areas.

If you want to learn more about the Azalea/Rhododendron family visit the Panaewa Zoo in Hilo. They have a great collection of Vireya or tropical Rhododendrons to view. You may also visit the new tiger and lots of interesting animal life from all over the world. .