Red azaleas

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White azaleas

Bright regal blossoms make azaleas a favorite in the spring garden. Most azalea varieties bloom from mid-April to mid-May in the mid-Atlantic area.

While the hardier deciduous azaleas, which lose their leaves in fall, are native, you may be more familiar with evergreen azaleas, originally from Japan. Because azaleas have been hybridized (cross-bred) over many years, there is a wide variety from which to choose.

Azaleas belong to the genus Rhododendron, and some small-leaved rhododendrons look like evergreen azaleas. To tell them apart, first look at a flower — most azaleas have only 5 or 6 stamens (the pollen-producing part of the flower), while most rhododendrons have 10 stamens.

Blossoms

The azalea’s crowning glory is its blossom. Many azalea varieties have two- to three-inch flowers, although the size varies greatly. Blossoms can be single (usually five petals), hose-in-hose (giving the appearance of one blossom inside another), double (stamens becoming petals), and even triple.

Azaleas may be early, mid or late bloomers depending on the variety. Include several in your landscape to enjoy flowers all spring and early summer. The trait to rebloom in the fall has been bred into Encore and ReBLOOM azaleas, among others.

It’s smart to purchase a plant in the spring while it’s blooming to ensure the color of the flowers. Typically, garden centers stock more azaleas when they are in bloom.

Colors

Aristocratic azalea flowers are white and various shades of purple, pink, red, reddish orange and yellow (deciduous only). They may be a single color or bicolor; they may have stripes, flecks, blotches, margins or sectors (all or part of one or more petals of a different color).

Even the leaves of some azaleas can provide color. The leaves of evergreen azaleas with darker red or purplish red flower colors typically show some red pigmentation in their foliage as the plant ages. Deciduous azalea leaves can turn yellow, red or orange in autumn before they fall.

Many deciduous azaleas are extremely upright, some reaching a majestic 20 feet tall. A few are low-growing ground covers, such as “Joseph Hill,” which grows only about a foot high. However, most are shrubs, from dense to open, that fall in between.

Typically, evergreen azaleas grow as high as they grow wide. There are even weeping azaleas such as ‘Pink Cascade.’ Read the plant tag to pick the right size and growth potential for your site.

Helping azaleas thrive

Azaleas can be grown as specimen plants (the focus of a garden), in borders and even in containers. Most azaleas prefer fairly mild, humid climates, such as those in metro Richmond. Make sure that the azalea you choose is hardy in Zone 7.

Select a planting site where azaleas will be protected from the wind by buildings, slopes, evergreen shrubs, or evergreen trees such as pine, juniper or spruce. Azaleas typically prefer filtered sunlight, not dense shade. Encore azaleas, however, do well in full sun.

Plant azaleas where there is good drainage and acidic soil with a pH of 4.5 to 6.0. Dig the hole twice the diameter of the root ball and only as deep. It is better to plant too shallow, rather than too deep. Never plant azaleas so deeply that the plant stem is covered deeper than it had been while growing in the container.

Mulch with coarse materials, such as partially decomposed oak leaves or pine needles about 2 inches deep, and water after planting.

Make sure to protect your azalea’s shallow roots from damage. Take care to keep azaleas hydrated during the summer months; however, do not water excessively in the fall.

Fertilize after blooming with a product specially formulated for azaleas and other acid-loving plants (for example, Espoma Holly-tone); do not fertilize after July 1. In the fall, replenish mulch to the two-inch depth. Pruning azaleas is not usually necessary.

Potential problems

Unfortunately, deer seem to enjoy azaleas as much as people do and may thwart the azalea’s accession to the throne.

The azalea lace bug is the most common insect culprit. It sucks plant sap from the underside of leaves, causing a pale stippling on their upper surfaces, giving leaves a grayish cast. The whole leaf appears white and drops early. Treatment plans for an infestation include horticultural oil, insecticidal soap, and neem-based products. Also troublesome can be aphids, leaf miners and scale.

The most common diseases that affect azaleas are Phytophthora root and crown rot (a fungus that thrives in poorly drained or wet conditions). Once an area is infected, the fungus cannot be eradicated from the soil.

Ovulinia petal blight, another fungal infection, is easily spread from flower to flower by wind, rain and insects. Select cultivars that are more resistant to problems such as azalea lace bug and Phytophthora. Stem bark splitting results from rapid temperature changes and freezing.

But don’t let these potential problems keep you from allowing azaleas to reign in your garden.

Lela Martin is a Master Gardener with the Chesterfield County office of the Virginia Cooperative Extension.