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Azaleas for the Landscape

Publication Number: P3705
View as PDF: P3705.pdf

Most Mississippi gardens have contained an azalea at some point. Azaleas are in the genus Rhododendron, which has more than 900 species. Azaleas are native to many parts of the world, but the most colorful varieties come from China, Japan, and the eastern United States.

There are many characteristics that make the azalea a beloved plant. They flourish with beautiful blooms that can provide an array of colors from mid-spring through early summer. Many varieties also offer colorful fall foliage. With dwarf, intermediate, and large varieties available, gardeners have a wide selection to choose from.

Azaleas are hardy from USDA climate zones 5 to 9. North Mississippi is in zone 7, and the extreme Gulf Coast area is in zone 9, making azaleas hardy throughout the state. All of these attributes make the azalea an excellent plant for Mississippi landscapes.

Planting

Azaleas can be used many ways in the landscape/garden area. They may be used as border/facer plants along a boundary, as background plantings to frame an area, as foundation plantings to build the design around, or in mass-planted groups to brighten up a landscape room.

Where to Plant

Some azaleas can grow in full sun, but most are best suited for a landscape area that has partial shade. This could be on the north side of the house or in a wooded area that receives filtered sunlight through trees. They do best in an acidic soil that has a pH between 4.6 and 6.0. A soil test is the best way to ensure proper soil acidity. Higher pH (greater than 6.0) results in poor growth and insect- and disease-stressed plants.

Azaleas prefer well-drained soil that has an abundant supply of peat moss. If the native soil is poorly drained, you should make raised beds. You can do this with landscape timbers or crossties, or by hilling the soil up 8 to 12 inches above ground level. Azaleas will not tolerate wet feet (roots)!

When to Plant

Most azaleas are container-grown and can be planted any time of the year. However, planting in the fall or early spring allows time for roots to establish before summer heat arrives. Plant bare-root plants during the winter dormant season.

How to Plant

Prepare a planting hole two to three times as wide as the root ball. Set plants in the hole at the same depth or slightly higher than where they grew in the nursery or container. Backfill with amended soil and water thoroughly. Adding lots of peat moss, leaf mulch, well composted sawdust, or other compost can make the soil more acidic, if needed. Finally, mulch the planting site with 3 to 4 inches of a mulch product or 6 to 8 inches of pine straw. Taper the mulch/straw to only 1 inch deep at the base of the plant.

Fertilizing

Have the soil tested and follow the fertilizer recommendations provided. If your soil has not been tested, apply 2 to 4 pounds of an acid-based fertilizer with a 2-1-1 ratio per 100 square feet of bed area. Fertilize individual plants with 1/4 to 1/2 cup of fertilizer in a uniform circle no closer than 1 foot from the base of the plant. Fertilize in early spring and again in early summer just after plants have finished flowering. Late or over-fertilization can result in little or no flowering, excessive vegetative growth, and possible winter damage if the plants do not harden off.

Pruning

Azaleas grow and set their bloom buds during the fall months. For this reason, prune them immediately after they have finished their spring bloom period. It is okay to wait until all the azaleas in the landscape have finished blooming to prune them all at once. The best method is to use hand-held pruners and remove only one-third of the overall plant. For more information, see Extension Information Sheet 204 Pruning Landscape Plants.

Variety Selection

There are azalea varieties to fit most any landscape situation. Dwarf varieties only grow to 1 to 2 feet tall, large varieties may reach 12 feet, and there are numerous varieties in between.

Three deciduous species grow natively in woodland areas of the state: Rhododendron canescens, the pink bush honeysuckle; R. austrinum, the yellow bush honeysuckle; and R. viscosum, the white swamp azalea.

Most of today’s showy azaleas are hybrids. Some of the major groups of cultivated azaleas are Indicas, Kurumes, Glenn Dale hybrids, Girard’s, Robin Hill, and the Satsukis. Varieties from the Indica and Kurume groups are grown more commonly throughout the state (see Table 1).

The Encore series of azaleas have also gained great popularity in Mississippi landscapes, with more than 25 varieties to choose from. This series is known for producing flowers in the fall, as well as in the spring. The Re-Bloom series from Greenleaf Nurseries and the Bloom-A-Thon series from Proven Winners are newer releases that should perform well here, also. However, these are newer cultivars that have not been fully tested for adaptation to all of Mississippi (Table 2).

Color and Flower Forms

Azalea flowers have a range of colors, including white, yellow, orange, scarlet, crimson, and purple. There are vivid sparkling shades, pastel tints, and pure whites. Some even have striped or flecked flowers.

The single-flower varieties have five petals with five to ten stamens. Other varieties may be double, semidouble, or the hose-in-hose (funnel) type. Azaleas flower abundantly, and, if you choose the right varieties, you may have flowers for up to 3 months (see Table 1).

Watering

Azaleas have an extremely fibrous root system that stays relatively shallow. A good watering schedule is essential during the growing season. Azaleas need the equivalent of 1 inch of rain every 7 to 10 days. It is best to water as deeply and infrequently as possible. The timing and amount will depend upon the soil type and drainage. For more information, see Extension Information Sheet 1670 The Plant Doctor: Watering and Plant Disease.

Common Diseases and Pests

Petal blight

Flowers become spotted and water-soaked and cling to the plant after they die. It is more severe in cool, moist springs. Remove old mulch and replace. Drench or spray with a fungicide. Unless you have a “hot” compost process, do not compost this material. Remove it well away from the property.

Leaf gall

Pale green or whitish, fleshy galls with curled or deformed leaves. Occurs more in cool, moist weather. Hand-pick and destroy affected leaves. Start spraying at end of bloom period and continue at 2- to 3-week intervals until mid-June.

Leaf spots

Brown/bronzed leaves, with tiny black fruiting bodies on leaves. Use a fungicide at end of bloom period and continue at 2-week intervals through growing season.

Winter injury

Entire branches turn brown and die during the growing season. Look for bark splitting near base of limbs or at ground. Use recommended varieties and keep plants in healthy condition. Water regularly during late summer and fall.

Nematodes

Leaves turn yellow and plants are stunted. They do not respond favorably to water and fertilizer. No chemical control available. Other conditions mimic nematode injury; collect a soil sample from root zone for nematode analysis.

Iron chlorosis

Leaves turn light green to yellow, then creamy white between the veins; but veins remain green. Caused by too high soil pH, making the iron unavailable. Lower soil pH by adding ferrous sulfate, finely ground sulfur, or aluminum sulfate. Treat foliage with iron chelate for temporary effects.

Azalea caterpillar

Causes sudden defoliation of leaves. Usually occurs in late summer or fall and is more common in the southern part of the state. Control with foliar sprays recommended for caterpillars.

Azalea lacebug

Upper surface of leaves has a gray, coarse-stippled appearance. Underside of leaves becomes discolored by excrement and cast skins. Treat with recommended soil-applied insecticides. For heavy infestations, also apply foliar insecticides when crawlers are hatching.

Scale insects

Usually on twigs or branches and have various colors and shapes. Some look like bits of white cotton and others are brownish. Treat with recommended soil-applied insecticides. For heavy infestations, also apply foliar insecticides when crawlers are hatching.

For more information on insecticides, see Extension Publication 2369 Insect Pests of Ornamental Plants in the Home Landscape.

Table 1. Common azalea varieties.

Indica

Approximate Bloom Date

Flower Color

Approximate Height

Brilliant

early to midseason

rose

3 to 4 feet

George L. Taber

midseason

white to pale pink

6 to 8 feet

Mrs. G. G. Gerbing

early to midseason

white

6 to 8 feet

Judge Solomon

midseason

purplish

6 to 8 feet

Formosa

early to midseason

rose lavender

6 to 10 feet

Pride of Mobile

midseason

watermelon pink

6 to 10 feet

Kurume

Approximate Bloom Date

Flower Color

Approximate Height

Snow

midseason

pure white

1 to 2 feet

Christmas Cheer

early to midseason

brilliant red

2 to 3 feet

Hino Crimson

early

dark red

2 to 4 feet

Hinodegiri

midseason

bright scarlet

3 to 4 feet

Coral Bells

midseason

shell pink

3 to 4 feet

Hershey Red

early

bright red

3 to 4 feet

Pink Pearl

early

soft pink with rose blotch

4 to 6 feet

Satsuki

Approximate Bloom Date

Flower Color

Approximate Height

Gumpo

late

white, pink

1 to 3 feet

Higasa

late

deep pink

1 to 3 feet

Amagasa

late

orange to red

2 to 3 feet

Macrantha

midseason

pink, orange, salmon

2 to 3 feet

Wakebishu

late

light pink

2 to 3 feet

Glenn Dale

Approximate Bloom Date

Flower Color

Approximate Height

Fashion

midseason

soft orange to rose

4 to 6 feet

Glacier

midseason

white

4 to 6 feet

Trouper

early

orange red

4 to 6 feet

Delaware Valley

early to midseason

pure white

4 to 6 feet

Rutherford

Approximate Bloom Date

Flower Color

Approximate Height

Red Ruffle

early

deep red

3 to 4 feet

Pink Ruffle

midseason

pink

4 to 6 feet

Robin Hill

Approximate Bloom Date

Flower Color

Approximate Height

Nancy

late

light purple to pink

2 to 3 feet

Conversation Piece

late

white, pink red

3 feet

Watchet

late

red

3 feet

Congo

late

vivid purple

3 to 4 feet

Girard

Approximate Bloom Date

Flower Color

Approximate Height

Rose

early

rose-red

2 to 3 feet

Renee Michelle

late

clear pink

2 to 3 feet

Pleasant White

mid- to late season

white

2 to 3 feet

Hot Shot

midseason

red

2 to 4 feet

Crimson

midseason

crimson

3 feet

Others

Approximate Bloom Date

Flower Color

Approximate Height

Hardy Gardenia

midseason

white

2 to 4 feet

Herbert

early

purple

3 to 4 feet

Midnight Flare

midseason

dark red

4 feet

Sunglow

midseason

purplish red

4 to 6 feet

Table 2. Repeat-bloom azalea varieties.

Encore Series Pinks

Bloom Form

Flower Color

Approximate Height

Autumn Coral

single

coral pink w/fuchsia center

2.5 feet

Autumn Carnival

semi-double

medium pink

3 feet

Autumn Cheer

single

medium pink

3 feet

Autumn Princess

semi-double

salmon-pink

3 to 4 feet

Autumn Sundance

single

deep pink

3 to 4 feet

Autumn Debutante

single

light pink

4 feet

Autumn Empress

semi-double

medium pink

4 feet

Autumn Jewel

single

pink

4 feet

Autumn Rouge

semi-double

light pink

4 feet

Autumn Sweetheart

single to semi-double

soft pink

4 feet

Autumn Carnation

semi-double

medium pink

4 to 5 feet

Autumn Sangria

single

dark pink

4 to 5 feet

Encore Series Reds

Bloom Form

Flower Color

Approximate Height

Autumn Ruby

single

ruby red

2.5 feet

Autumn Bravo

single

red

3 feet

Autumn Embers

semi-double

deep red

3 feet

Autumn Sunset

semi-double

orange-red

4 feet

Autumn Monarch

semi-double

dark peach-orange

5 feet

Encore Series Purples

Bloom Form

Flower Color

Approximate Height

Autumn Lilac

single

lavender-violet

3 to 4 feet

Autumn Amethyst

single

dark lavender

4 feet

Autumn Royalty

single

dark purple

4 to 5 feet

Encore Series Whites

Bloom Form

Flower Color

Approximate Height

Autumn Ivory

single

white

2.5 feet

Autumn Angel

single

pure white

3 feet

Autumn Lily

single

white

4 to -5 feet

Autumn Moonlight

semi-double

white

5 feet

Encore Series Bi-colors

Bloom Form

Flower Color

Approximate Height

Autumn Chiffon

single

light pink w/dark pink center

2.5 feet

Autumn Starlight

single

white w/pink flecks

3 to 4 feet

Autumn Sunburst

single to semi-double

coral pink w/white edges

3 to 4 feet

Autumn Twist

single

white w/purple stripes

4 to 5 feet

Autumn Belle

semi-double

pale pink

5 feet

Re-Bloom Series

Bloom Form

Flower Color

Approximate Height

Cherry-Pink Prestige

double

cherry pink

1.5 feet

Blush Elegance

single

light pink

2 feet

Fuchsia Extravagance

single

fuchsia

2 feet

Pink Adoration

single

pink

2 feet

Purple Spectacular

single

purple

2 feet

Coral Amazement

triple

coral

2.5 feet

Firebrick Fame

single

red-orange

2.5 feet

Red Magnificance

double

red

3 feet

White Nobility

single

white

3 feet

Bloom-A-Thon Series

Bloom Form

Flower Color

Approximate Height

White

single

white

3 feet

Pink Double

double

pink

4 feet

Red

single

red

4 feet

Lavender

single

purple

4 feet


Publication 3705 (POD-09-21)

Revised by Jeff Wilson, PhD, Assistant Professor, North Mississippi Research and Extension Center, from an earlier edition by David Tatum, PhD, former Extension horticulturist.

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Authors

Portrait of Dr. Jeff Wilson
Assistant Professor
Horticulture: State Master Gardener Coordinator

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