Azaleas Show Their Stuff In Spring

Daniel Gill, Merrill, Thomas A.  |  4/22/2005 12:39:50 AM

Get It Growing News For 03/04/05

By Dan Gill
LSU AgCenter Horticulturist

Azaleas are spring showoffs, even though some newer varieties now bloom in other seasons.

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

No other shrub in the landscape can beat azaleas for flower power when they are 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 they are reliable landscape plants if they are planted properly and in the right growing conditions.

Azaleas require good drainage but also need an even supply of moisture. They will not thrive in a location that is constantly wet or constantly dry.

Many azalea cultivars will tolerate full sun if 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. If 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, composted finely ground pine bark or peat moss.

Azaleas also prefer an acid soil. 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 acid.

Then sprinkle a light application of an all-purpose or acid-loving plant fertilizer over the bed. Thoroughly incorporate everything into the bed (a garden tiller is excellent for this step), rake it smooth and you’re ready to plant.

Arrange the azaleas in the bed while they are still in their pots to get the spacing and arrangement right. When you get ready to plant and take the plant out of the pot, 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.

You should always 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!

As you’re planting, gently firm the soil around each plant with your hands to eliminate air pockets.

In addition, keep in mind that azaleas are shallow rooted and benefit greatly from mulch. As soon as they are planted, mulch the bed with about 2 inches of pine straw, leaves or pine bark.

Finally, thoroughly water the bed to finish settling the soil. It will be important to water your newly planted azaleas thoroughly and regularly whenever the weather is dry this coming summer.

Azaleas you already have growing in the landscape may be fertilized as soon as they finish flowering this spring. 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 various products, and acidify the soil with sulfur, copperas or a liquid soil acidifier.

As flowering finishes, evaluate your azaleas for any pruning they may need. April and May are good months to trim your bushes, but do it only if it’s necessary.

Generally, a little shaping is all that is required, although controlling size is a common reason for pruning. This is especially true if large-growing azalea cultivars were planted where smaller ones should have been used. Unless you are trying to create a formal clipped hedge, avoid shearing azaleas with hedge clippers, since this destroys their attractive natural shape. It is better to use hand pruners to individually remove or shorten selected branches to achieve the desired shape and size.

Azalea lace bugs are a leading pest of azaleas and already are 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 of these pests per year, but most damage from lace bugs 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 damage. Stop the damage early, because once it occurs, the leaves will not regain their healthy appearance.

Orthene and Malathion are effective in controlling lace bugs. Applications should be directed at the underside of the leaves for best control.

Get It Growing is a weekly feature on home lawn and garden topics prepared by experts in the LSU AgCenter. For more information on such topics, contact your parish LSU AgCenter Extension office or visit our Web site at www.lsuagcenter.com. A wide range of publications and a variety of other resources are available.

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Contact:     Dan Gill at (225) 578-2222 or dgill@agcenter.lsu.edu
Editor:        Tom Merrill at (225) 578-2263 or tmerrill@agcenter.lsu.edu

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