Fundamental Facts
HARDINESS: Zones 4 to 9
PREFERRED SOIL pH: Acid
PREFERRED SOIL TYPE: Moist, loamy well-drained
PREFERRED LIGHT: Partial to full shade
ATTRIBUTES: Tubular flowers in a range of colors; for beds, woodland gardens, pots
SEASON OF INTEREST: Spring to early summer for flowers; year-round for evergreen types
FAVORITES: All native species, Knap Hill, Northern Lights, Indian, Encore hybrids
WHERE IT GROWS BEST: Open woodland settings
QUIRKS: Prefers shallow planting and acid soil with a pH of 4.5-6.0
GOOD NEIGHBORS: Dogwood, ferns, hosta, holly, pines, serviceberry, silverbell, spring bulbs
POTENTIAL PROBLEMS: Root rot; lace bugs
PRUNING: Remove damaged wood or shape plants after flowering
CRITTER RESISTANCE: Good
SOURCE: Nursery plants
DIMENSIONS: 2-20 ft (0.6-6.1 m) tall, 2-12 ft (0.6-3.7 m) wide
Azalea in the Landscape
The signature shrub of springtime in many parts of the country, azaleas come in an array of sizes, flower colors, and growth habits. Many are hardy to Zone 4, although evergreen types are generally hardy only to Zone 6. Related to rhododendrons, azaleas are distinguished from them by their smaller, oval leaves, tubular flowers, and usually shorter, twiggier stature.
Azaleas cover themselves in white, pink, lavender, yellow, orange, or red blossoms in spring. They range from 2 ft (0.6 m) tall dwarfs to 20 ft (6.1 m) giants. Smaller azaleas are often used as foundation shrubs, because they thrive in the part-day shade cast by buildings. They also grow well in pots and flower beds and make an elegant path edging, while the taller types are substantial enough to mix into a border of shrubs or stand beneath trees. Some varieties are deliciously fragrant.
All in the Family
It's always safest to buy azaleas locally, because nurseries sell plants adapted to local conditions. Where winters are cold, look for Minnesota-bred Northern Lights hybrids, which can tolerate temperatures as low as -30°F (-34°C). Deciduous hybrids from Europe, such as the popular Exbury and Knap Hill azaleas, are hardy to Zone 5. In warm climates, look for evergreen azaleas bred in the southeastern states, often called Indian hybrids, of which the pink-flowered 'George Tabor' is a popular example. There are also new reblooming evergreen azaleas, such as the Encore hybrids, which bloom in spring and again in fall.
Native North American species are easy to grow and provide decades of pleasure, often outlasting the hybrids. In cold climates, try the spice-scented white swamp azalea (R. viscosum) or pink pinxterbloom azalea (R. periclymenoides), both hardy to Zone 4. Good choices for warm-summer, mild-winter areas include flame azalea (R. calendulaceum), with yellow-orange flowers, and plumleaf azalea (R. prunifolium), with crimson blooms that open in midsummer. Both are hardy to Zone 5. Western gardeners can grow the Western azalea (R. occidentale), which has creamy pink flowers.
Growing Azalea
Plant azaleas where they'll be shaded from summer sun, and in fertile, moist, well-drained soil. To prevent root rot, barely cover their roots with soil. In poorly drained areas build a berm of soil about 1 ft (0.3 m) high to plant them on. Water well and mulch with a 3 in (7.6 cm) layer of organic mulch to retain moisture. Fertilize plants every spring with a formula designed to maintain soil acidity. Prune only to remove damaged or dead wood or to control plant size, preferably after the flowers fade in early summer.
Leaves that look bleached may have fallen victim to lace bugs, small sucking insects that can be found on leaf undersides. Control them by applying insecticidal soap per label directions.
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