Azaleas are spring showoffs

Richard Bogren, Gill, Daniel J.

For Release On Or After 03/26/10

By Dan Gill
LSU AgCenter Horticulturist

With the introduction and more common use of alternate-season-blooming azaleas, such as the increasingly popular Encore azaleas, it’s not unusual to see azaleas blooming during late summer, fall and winter. Even so, March through April is still the time when azaleas really strut their stuff.

No other shrub in the landscape can beat azaleas for flower power when they’re in full bloom. Although the floral display may be relatively short, it ensures the continued popularity of this traditional Southern shrub. Azaleas may be planted now and are quite reliable if they’re planted properly in the right growing conditions.

Azaleas require good drainage but also need an even supply of moisture. They won’t thrive in a location that’s constantly wet or constantly dry.

Many azalea varieties will tolerate full sun if they’re provided with adequate moisture. Generally, however, azaleas grow best when they receive some shade during the day. Four to six hours of morning sun provided by an eastern exposure is considered ideal. Azaleas tend to have sparse foliage, look leggy and bloom poorly when planted in too much shade. Grown in too much sun, azaleas may wilt constantly during hot, dry weather and scorch on their leaf edges.

Careful bed preparation prior to planting will help ensure success. A soil high in organic matter is important. After removing unwanted grass or weeds from the bed, turn the soil to a depth of at least 8 inches, break up the clods and spread 3-4 inches of compost, aged manure, finely ground pine bark or peat moss.

Azaleas prefer an acid soil, so if the soil in your garden is alkaline, apply ground sulfur or copperas (iron sulfate) according to package directions to help make the soil in the bed more acidic. Finally, sprinkle a light application of an all-purpose or acid-loving plant fertilizer over the bed. Thoroughly incorporate everything into the bed, rake it smooth and you’re ready to plant.

Arrange the azaleas in the bed while they’re still in their pots to get the spacing and arrangement right. When you take the plant out of the pot to plant, you may see a very dense network of roots around the outside of the root ball. This is not uncommon in container-grown plants. Use a knife to vertically cut into the root ball in several places, or use your fingers to pull apart the root ball and loosen it up. This will encourage the roots to grow out into the surrounding soil and increase the plant’s chances of survival this summer.

Plant azaleas so that the top of the root ball is at or slightly above the soil level in the bed. Do not plant them too deep! Gently firm the soil around each plant with your hands to eliminate air pockets.

Azaleas are shallow-rooted and benefit greatly from mulch. As soon as they are planted, mulch the bed with about 3 inches of pine straw, leaves or pine bark. Finally, thoroughly water the bed to finish settling the soil. It will be important to thoroughly and regularly water your newly planted azaleas whenever the weather is dry.

Azaleas already growing in the landscape should be fertilized as soon as they finish flowering. Apply a general-purpose or acid-loving plant fertilizer following label direction.

If the leaves at the ends of the branches are yellowish-green with green veins, the azaleas need iron. This condition is common when azaleas are grown in alkaline soil. Treat them with chelated (pronounced KEY-lay-ted) iron, available in such products as Liquid Iron or Ironite, and acidify the soil with sulfur, copperas or a liquid soil acidifier.

As flowering finishes, evaluate your azaleas for needed pruning. April and May are good months to trim your bushes, but only do it if it’s necessary. Generally, a little shaping is all that’s required, although controlling size is a common reason for pruning. This is especially true if large-growing varieties were planted where smaller ones should have been used.

Unless you’re trying to create a formal, clipped hedge, avoid shearing azaleas with hedge clippers because this destroys their attractive natural shape. It’s better to use hand pruners to individually remove or shorten selected branches to achieve the shape and size you want.

Azalea lace bugs are a leading pest of azaleas and are already active. A small insect, the lace bug attacks azalea foliage, causing it to become stippled with small white dots. The lace bugs live on the underside of the leaves, and the lower surface of the leaves will have dark brown spots. There are several generations per year, but most damage seems to occur from the early generations in spring.

Inspect the healthy new growth of your plants regularly over the next six weeks and treat as soon as you see the first signs of insect damage. Stop the damage early because once it occurs, the leaves will not regain their healthy appearance. Orthene, malathion and light horticultural oils are effective in controlling lace bugs. Applications should be directed at the underside of the leaves for best control.

Azaleas are among the most beautiful of our spring-flowering shrubs. Planted in the proper growing conditions and provided the right care, they are reliable, long-lived shrubs that play an important role in traditional Southern landscaping.

Rick Bogren

1/4/2011 1:07:13 AM
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