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Evergreen Azaleas with butterfly

Many varieties of evergreen azaleas thrive in Alabama’s soils. Learn the best variety for your landscape along with tips on how to plant, care for, and control pests and diseases in your prized azaleas.

Azaleas are a staple in Southern gardens and the most popular flowering shrub in Alabama. They are especially appealing because they come in various colors, shapes, and sizes. With so many cultivars available, you are likely to find an azalea or two or even three that fit nicely in your landscape.

Many of the evergreen azaleas we enjoy today can be traced back to Asia. We will focus on the more common evergreen azalea groups that have a history of performing well across the state.In making a selection for your landscape, you need to consider a cultivar’s mature size, growth habit, flower color, and cold hardiness (both of its foliage and flowers). These factors can be dramatically different among cultivars.

Plant Selection

Kurume Hybrids

The first Kurume azaleas were brought to the United States from Japan around 1915, causing a wave of popularity for these evergreen azaleas. With the earliest bloom time each spring and a manageable size of 4 to 6 feet, they are some of the most common cultivars found in Alabama. They grow more slowly and have smaller leaves and flowers than Southern Indian azaleas. Most Kurume azaleas are cold hardy and can be grown in north and central Alabama. Because they are native to mountainous regions of Asia, Kurume azaleas are not as well adapted for south Alabama and coastal areas.

You can choose from many colors, including lavender, pink, orange, red, and white. Popular varieties and colors are ‘Hinode Giri’ (red), ‘Snow’ (white), ‘Coral Bells’ (pink), ‘Sherwood Red’ (red), and ‘Pink Pearl’ (salmon).

Southern Indian Hybrids

Commonly referred to as Indica azaleas, Southern Indian hybrids are noted for their large flowers and leaves and fast growth rate. They are well suited for southern Alabama, where they can grow to be over 8 feet tall. They are not as cold hardy as other azaleas.

In the northern half of Alabama, the flower buds of Indica azaleas are more commonly injured from frost than other popular hybrids, such as Kurume and Glenn Dale. In mountain areas, these cultivars are often injured or killed if plants freeze before they are completely dormant in late fall.

Indica azaleas are a great choice for the southern and central portion of the state; however, be sure to consider their mature size before planting. They can be pruned to manage their height, but they grow fast, and multiple prunings may be required each year to maintain a desirable size. Indica azaleas do great as a screen or border planting in larger yards.Popular varieties and colors are ‘Formosa’ (rose purple), ‘George Lindley Taber’ (light pink), ‘Mrs. G. G. Gerbing’ (white), and ‘Pride of Mobile’ (rose pink).

Satsuki Hybrids

Satsuki cultivars are very popular in Japan where some grow as tall as 5 feet. The Satsuki hybrids found in the United States are more compact, low-growing plants that produce an abundance of small leaves. Their compact size makes them ideal as foundation plantings.

In Alabama, most Satsuki azaleas bloom from mid- May through mid-June. In fact, Satsuki is the traditional Japanese word for May. Many produce very large, flat flowers that are 4 to 5 inches wide. Colors may vary widely, even on individual plants. Striped flowers, or even flowers with different rings of color, are common. They make a great addition to the landscape because they extend the azalea season and offer blooms past the time of our last frost dates, especially in northern Alabama.

Popular varieties are ‘Gumpo White’ (white), ‘Gumpo Pink’ (pink), ‘Amagasa’ (red), ‘Wakaebisu’ (pink), and ‘Flame Creeper’ (salmon).

Glenn Dale Hybrids

Benjamin Y. Morrison, the first director of the US National Arboretum, began breeding these azaleas in 1930 at the Plant Introduction Station in Glenn Dale, Maryland. Over 445 Glenn Dale cultivars were introduced between 1940 and 1952.Morrison bred these azaleas to bloom in mid and late season. Some varieties bloom earlier than the Kurumes, and many are midseason bloomers, reaching a peak in late April or early May in central Alabama. Some of the excellent late-flowering varieties do not bloom until early June in the Birmingham area. Many varieties have the vigorous growth characteristic and large flower size of the Southern Indian azalea plus much greater cold hardiness.

Common varieties are ‘Dayspring’ (pink), ‘Glacier’ (white), ‘Fashion’ (begonia rose), and ‘Ben Morrison’ (orange red).

New Reblooming Azaleas

Some of the exciting new varieties of azaleas available today are those that have been bred to bloom not only in the spring but also in the summer and fall. Many of these azaleas are patented plants and sold under the trade names of Encore Azalea and Proven Winners Bloom-A-Thon.

There are over 30 Encore Azalea cultivars. Some popular ones include ‘Autumn Royalty’ (purple), ‘Autumn Carnation’ (pink), ‘Autumn Twist’ (bicolor), ‘Autumn Fire’ (Red), ‘Autumn Coral’ (salmon), and ‘Autumn Moonlight’ (white). Reblooming azalea cultivars by Proven Winners are ‘Bloom-A-Thon Pink’, ‘Red’, ‘White’, and ‘Lavender’.

Following are other notable azalea cultivars:

  • Rutherford hybrids: ‘Pink Ruffles’ (pink), ‘Red Ruffles’ (red)
  • Carla hybrids: ‘Sunglow’ (rose pink), ‘Wolfpack Red’ (red)
  • Korean azalea: ‘Poukhanense’ (lavender)
  • Harris hybrids: ‘Irish Cream’ (white), ‘Midnight Flare’ (dark red)
  • Nuccio’s hybrids: ‘Nuccio’s VooDoo’ (white with lavender border)
  • Linwood hybrids: ‘Hardy Gardenia’ (white)
  • Girard hybrids: ‘Crimson’ (red), ‘Pleasant White’ (white), ‘Christina Marie’ (Pink)
  • Robin Hill hybrids: ‘Conversation Piece’ (pink), ‘Watchet’ (red), ‘Hilda Niblett’ (dark red), ‘Congo’ (purple)
  • Shammarello hybrids: ‘Elsie Lee’ (lavender)
  • Pericat hybrids: ‘Hampton Beauty’ (soft pink), ‘Sweetheart Supreme’ (light pink)
  • Aromi Azaleas: ‘Amelia Rose’ (lavendar pink)

Buying Plants

You will get the most effective display of flowers by planting a mass of a single variety instead of using many varieties and colors together. Including white-flowered varieties can really make the warm colors more vibrant.

Purchase plants that are sturdy with a good branch system. Do not buy plants with weak, spindly growth. Spindly growth usually means the plant has a poor root system or that plants were grown too closely spaced in the nursery. The best size to buy is 12 to 16 inches tall. Smaller plants are more likely to be injured by cold.

Azaleas are usually bought as container-grown plants. They are sometimes pot-bound, which means they have a mass of roots growing around the outside of the ball of soil. Take the plant out of the container before you buy it. Make sure that the roots are healthy and completely fill the pot. If you buy a pot-bound plant, massage the root ball to loosen some of the roots before planting or make four shallow vertical cuts around the root ball. Tease out the roots before planting to ensure that they spread and grow away from the original ball of container potting medium.

Planting Azaleas

Where to Plant

When choosing a planting site, consider the amount of light and space along with soil conditions that your plant will be exposed to.

Understanding sun and wind exposure is key to growing success. Pick a place with light to moderate shade. Azaleas that receive some shade during the winter usually suffer much less cold damage. During hot weather the flowers last much longer on plants in filtered shade than on those in full sun. Late-blooming varieties need to be in partial shade to prevent sunscald to the flowers.

Pine trees with moderate filtered shade give ideal protection for azaleas. However, very heavy shade throughout the day may reduce flower production and result in weak growth. Evergreen trees or tall shrubs with low branches make good windbreaks and attractive backgrounds for an azalea planting. Shallow-rooted trees, such as oaks, elms, and maples, may compete with azaleas for moisture and nutrients.Check the soil pH of your site before you buy azaleas. Azaleas require an acidic soil pH to grow properly. If the pH is above 6.5 you can expect to spend additional money and effort to maintain a pH in the proper range for plant growth. It may be to your advantage to consider other kinds of landscape plants for that site. With higher pH levels, iron in the soil is not readily available to the plant, resulting in iron chlorosis. This condition causes the area between the veins to turn yellow or light green, while the veins remain a darker green. Chelated iron is an effective way to temporarily correct iron deficiency symptoms. Use it at the rate recommended on the product label.

When to Plant

Azaleas can be planted any time of the year if proper attention is given to providing adequate water. Most people buy azaleas in the spring when the plants are blooming so that they can choose the right color combinations. However, fall is probably a better time to plant, allowing the roots to become established during cooler weather. If the azalea is planted in the spring or summer months, watering two or three times weekly is necessary for survival.

Preparing the Soil

Proper soil preparation is the basis for successful azalea culture. A soil test is essential in determining soil nutrient needs as well as pH. Get information and supplies for soil testing at your county Extension office.

For good results, spend about the same amount of money for organic material as you spend for the azalea plants. Organic matter does several important things for the root growth of azaleas. It loosens and aerates tight clay soils, and it helps sandy soils to hold more water for a longer period of time.

There are several good organic materials. Peat moss is best to use, followed by ground pine bark, leaf mold from the woods and composted leaves, and composted sawdust. A general rule is to add no more than 20 percent amendments to the backfill.

Planting

To prevent overcrowding, space azaleas based on their ultimate mature size. Water azalea plants in the container to increase plant water content prior to installation.

If you are planting a bed of azaleas, spread 5 to 6 inches of organic matter on the surface, working it in to a depth of 12 inches. If azaleas are to be planted in individual holes rather than beds, dig each hole two to three times the width of the container but no deeper.

If you are working with a clay soil, dig the hole to a depth that will allow the top of the root ball to stick up about 1 inch above the surface of the surrounding soil. Deep planting often causes stunted growth or may even cause the plant to die.

Set the plant in the hole and add amended soil, lightly firming it around the root system. When the hole has been filled, water it thoroughly to further settle the soil. The goal is to simply remove air pockets around the roots, not to compact the soil. Structure and valuable air space are often lost in packing, and the plant suffers.

Azalea Care

Mulching and Watering

pink AzaleaAzaleas benefit from a 2 to 3 inch layer of mulch. Pine straw and pine bark are excellent mulch choices and are usually easy to find. Azaleas must be watered during dry periods and after initial planting. The months from August through October are critical times to supply additional water. Good mulch also helps to reduce the amount of water you will need to use as well as the number of times you have to water. If mulch is used, a heavy watering once a week should be enough during dry periods. Watering two or three times a week for the first 6 to 8 weeks after planting is beneficial.

Fertilization

To ensure proper fertilization of azaleas, base your application amounts on soil test recommendations. A soil test should be taken every 2 to 3 years. In the absence of a soil test, use an all-purpose fertilizer, such as 8-8-8 or 14-7-7, on soils with medium or low fertility. Some special azalea–camellia formulations cater to the acidic soil requirements of these plants by providing part of the plant nutrients in a slow-release form. In many cases, these are very good for azaleas. The recommended fertilizer amount should be divided, with half applied after blooming and half in July, rather than applied all at one time.

Pruning

Although not required, azaleas can be pruned without damaging the plant and without interfering with future flower production. The best time to prune is soon after the flowering period in the spring. Shaping to maintain a natural form is preferred. Prune back branches that have grown out of the main body of the plant. Do not shear unless your intention is to create a formal hedge, espalier, or topiary plant. Shearing destroys the natural form of the plant.

Azaleas often become too large for the area they occupy, especially when they are used as foundation plants around a home. If this happens, cut back the large plants to 6 to 12 inches above the ground shortly after they bloom. When new growth buds appear on the stem, the new stems and leaves will grow very fast. Pinch out any long, unbranched shoots that develop to force a branch system. Be sure to keep the soil moist for several days after severe pruning.

Insects and Diseases

Following are several of the most damaging insects and diseases that attack azaleas.

Azalea bark scales are white, oval-shaped insects that are covered with fine threads of a wax-like secretion. Unlike most covered scales, they can move from one plant to another. They are usually found in the axils of branches and stems.

These scales give off large amounts of a sweet, sticky substance called honeydew. A sooty mold fungus grows on the honeydew causing the branches and stems of heavily infested plants to look black and unattractive. In severe cases, branch dieback can occur. Apply systemic insecticides or horticultural oil in late April to early May, after the azaleas bloom.

Azalea lace bugs are the main nuisance insect pest found on azaleas. These small insects have black bodies and colored or variegated, lace-like wings. They feed on the underside of leaves. The upper leaf surface opposite the feeding areas becomes speckled, and the leaf looks light or bleached and eventually turns brown.

Lace bugs give off large amounts of a dark, sticky substance on the underside of leaves. The substance may drop from the plants. Black globules on the lower surface of the leaves are an obvious symptom of this insect. Apply foliar insecticides containing bifenthrin, cyfluthrin, permethrin, or acephate when the damage first appears to prevent unsightly damage.

Azalea caterpillars are colorful, hairy insects capable of completely defoliating azalea plants, especially large-leaf Indica varieties. The full-grown caterpillars are approximately 2 inches long with a reddish head and black body featuring rows of yellow or white spots and white hairs. The immature caterpillars are red to brownish black with white to yellow stripes and are about 1⁄2-inch long.

Most outbreaks and damage occur during late summer to early fall (August to September). Because they can rapidly defoliate azalea plants, it’s important to detect the caterpillars early before severe damage occurs. Apply foliar insecticides containing Bacillus thuringiensis (Bt), spinosad, bifenthrin, cyfluthrin, permethrin, or acephate.

Spider mites puncture the tissues of leaves and flowers with needle-like mouthparts and suck juices from the plant. Browning of older leaves is one of the first signs of a spider mite infestation. The feeding destroys the green pigment, giving the leaves and flowers a speckled appearance. As mites multiply, entire leaves become discolored and distorted, and they may drop off.

These pests are very small and feed mainly on the underside of leaves. They often go unnoticed until plant damage is severe. The southern red mite is one of the more common mites on evergreen azaleas and is more prolific during cooler weather in spring and fall. Light infestations of mites can be controlled with an application of horticultural oil or insecticidal soap.

Leaf gall is a common spring disease of azalea, caused by the fungus Exobasidium. Young leaves and flowers that are infected become thickened, fleshy galls that are pale green in color. Whole leaves or parts of leaves may become infected. As the galls age, they turn white from masses of spores produced on the surface of the gall.

The most practical method for control of this disease in home landscapes is to hand remove and discard all galled leaves and flowers as soon as they are detected and before they turn white from spore formation. Planting azaleas in areas that provide good air circulation and avoid deep shade also will help you to avoid leaf gall. Leaf gall rarely causes enough damage to require fungicide sprays.

Sunglow Azalea

Lichens are gray-green leafy or crusty growths on the stems of plants that are in declining health or vigor. The lichen itself does not infect or damage the plants and isn’t the reason for their decline. Instead, heavy lichen growth is usually a sign that the plant needs to be fertilized or mulched. Once the vigor of the plants starts to improve, the lichens will fade away.

Phytophthora root rot is one of the most damaging diseases of azaleas and is most common in landscape plantings in poorly drained soils. Yellowing of the foliage (particularly at the shoot tips), leaf shed, slowed plant growth, and limb dieback may occur in the early stages of the disease. Symptoms typically first appear on one plant and spread to others. Raising the planting area to improve soil drainage, planting resistant species, and using fungicides can all help reduce the chance of this disease reoccurring.

Phomopsis dieback is a common fungal disease affecting older landscape azaleas. The first symptom is an individual branch dying on an otherwise healthy plant. A closer look at the dying branch often reveals a chocolate brown section of discolored wood just under the bark surface. Environmental stresses, such as drought or cold injury, can predispose the plants to infection.

Prune all infected branches by cutting a few inches below the discolored wood. Disinfect pruning tools between cuts with a diluted bleach solution (1 part bleach, 9 parts water) or 70 percent rubbing alcohol. Application of fungicide sprays containing either thiophanate-methyl or mancozeb after pruning may help prevent additional disease.Prevent future problems by avoiding environmental stresses and maintaining good growing conditions for the azalea. This includes watering during dry weather, maintaining an adequate layer of mulch in landscape beds, and avoiding cold and other injuries.

Leaf spots are caused by several different fungi. These spots are unsightly but rarely harm the overall health of the plant. In extreme cases, the plant may suffer early leaf drop. Cultural methods, such as removing fallen leaves and keeping the foliage dry by not wetting the leaves when watering, can help to control the disease. Fungicide sprays containing thiophanate-methyl and chlorothalonil can be used to prevent serious foliage damage.

Azalea Propagation

Plant propagation of an azalea is somewhat more difficult than planting a container-grown azalea. Generally, most evergreen azaleas are easy to propagate. Azaleas are propagated from seeds, stem cuttings, root cuttings, layers, and grafting. Stem cuttings are the most popular method.

Whatever method of propagation is used, sanitation and cleanliness is very important for success. The stock plants should be healthy, and the equipment and areas used to prepare and propagate the plant (e.g., greenhouse or cold frame) should be disinfected.

Not all species can be propagated using the same method. Each of the several methods of propagation has advantages and disadvantages.

Propagation by Stem Cuttings

azalea cuttingPropagation by cutting is used most frequently for evergreen azaleas. When using this method, make cuttings in June and July from new wood of healthy, mature plants. Suitable new wood should snap when broken. Cuttings should be 3 to 6 inches long with the leaves removed from the lower one-third to one-half of the cutting. Insert the cuttings 1 to 1 1⁄2 inches deep in the rooting medium. The rooting medium can vary from equal parts of perlite and peat, to 1 part peat and 2 parts perlite, to a combination of bark, peat, and perlite. Before inserting the cuttings, the rooting medium should be thoroughly moist (not wet) and firm.

Flats or individual pots may be used depending on preference or the quantity of cuttings. Azalea cuttings can be rooted outside in a shady area if humidity is high, in a greenhouse under a mist system, or under enclosed plastic structures in shady areas. Rooting normally will occur in 4 to 6 weeks.

The problem in rooting all cuttings is trying to get roots initiated before the cuttings dry out. You can prevent drying by increasing humidity, increasing shade, reducing air movement, and maintaining 100 percent humidity. Rooting hormones such as Hormex, Hormodim, Dip & Grow, Garden Safe Take Root Rooting Hormone, and others also help to increase the number of roots on the cutting.

Propagation by Layering

Layering is a modification of propagation by stem cuttings. It is a slow process, but it can be useful if the number of plants to be propagated is small. Branch layering is the easiest method of layering. A low, sweeping branch is selected and bent to the ground. A wound is made on the stem by making an upward cut 1 to 1⁄2 inches in length along the underside of the branch. The branch is buried 3 to 4 inches deep at the cut. The top of the branch is bent upward. The buried part of the branch should be pegged down with wire or a rock and covered with mulch. It frequently takes more than a year before the new plant can survive on its own roots. For the home gardener, however, this is often the easiest method to get a few extra plants.

Conclusion

Azaleas are without a doubt deeply rooted in our Alabama culture. These prized evergreen plants produce some of the most spectacular and highly anticipated spring flower shows each year. With so many choices available today, find a prominent place in your home landscape for this treasured Southern plant.

 

 

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