How to Grow Azaleas

By Andrea Pisani Babich

Nothing heralds the beginning of spring more extravagantly than the profusion of showy flowers on azalea bushes. These members of the Rhododendron family promise the end of long, cold winter nights and the glory of warm, summer days.

Some early-season varieties can bloom as early as February or March in warmer climates. Mid-season azaleas display their seasonal splendor from April to June, while late-season varieties decorate summer gardens between July and September. With some careful planning, you could enjoy abundant azalea flowers and the delightful butterflies and hummingbirds they attract for a full eight months of the year.

With color and beauty that reign supreme in any space, it’s no wonder azaleas are called the “Royalty of the Garden.” Low maintenance and highly rewarding, azaleas are easy to welcome into your garden without the fanfare of most monarchs.

How to grow azaleas

Because there are so many varieties of azaleas, they can thrive in gardens throughout most of the United States in USDA plant hardiness zones from 4 to 9. All you need is a location that enjoys dappled sunlight and is filled with well-draining, acidic soil. The best times to plant azaleas is in late spring or early fall.

Planting and watering

Azaleas have shallow roots that will rot in soggy soil, but there are some steps you can take to keep their roots moist but not waterlogged.

  • Plant the root ball no deeper than just below surface of the soil. In denser soil, plant the root ball higher so that the top is several inches above the soil level. Create a mound of soil around the root ball.
  • Water deeply when the soil begins to dry out (usually signaled by drooping leaves).
  • Mulch with two to four inches of pine straw, leaves, pine bark, or wood chips to keep soil from drying out and prevent water from pooling up. Leave about an inch around the stem.

How to fertilize azaleas

As long as your soil is sufficiently acidic, your azaleas should not need fertilizing. The decomposing mulch will provide all the nutrients your azaleas need to thrive and produce brilliant flowers year after year.

How to prune azaleas

Azaleas look best when they have a natural shape. Shaping them into cubes or straight-sided hedges often reduces the number of flowers that give these plants their star power. Pruning thoughtfully can help azaleas maintain a compact shape as well as encourage fuller growth.

You should prune your azalea plants after the flowers have faded but before the new blossom buds appear, which can be as early as the beginning of July.

Here’s how to prune and trim your azaleas:

  1. First remove branches that have become dead wood.
  2. Then remove two or three branches that are too tall or extend beyond the shape or size you desire. Cut close to a side branch that is growing in the desired direction. Use the same process the following year and the next until you have achieved the shape you desire.
  3. Minimize shock to the plant by pruning just a few branches each year.
  4. Avoid cutting back any branch more than a third.
  5. Use clean cutting shears and sterilize them with denatured alcohol, rubbing alcohol, or bleach after pruning.

Common azalea pests and problems

Azalea lace bugs are one of the most common pests affecting azaleas. These black bugs appear on the underside of leaves that turn yellow or white. Spraying leaves with insecticidal soap in late spring or fall will control this pest.

Spider mites lay eggs on the leaves that become flecked with yellow. You may also notice fine webs on the leaves. Spray the undersides of leaves with an insecticide like acephate or dimethoate.

Leaf gall appears as pale green or white fleshy galls or swollen growths on the azalea leaves. Leaves may also curl or become deformed. You can control leaf gall by hand-picking the leaves and destroying them to prevent spread. At the end of the blooming season, spray plants with a fungicide twice a month until mid-June.

Types of azaleas

There are thousands of varieties of azaleas, many of which are hybrids, but they all fall into two main categories:

1. Evergreen azaleas are native to Japan and remain green all year round. They are classified in two subseries:

  • Obtusum subseries, which contains more than 40 species
  • Tashiroi subseries, which contains one only species

2. Deciduous azaleas are native to North America and lose their leaves in the fall. There are 17 varieties of these azaleas, and they are divided into three groups:

  • The white group
  • The pink group
  • The orange to red group

A word about azalea colors

As the group names suggest, the azalea color palette includes apricot, coral, lavender, burgundy, gold, white, and many variations on these shades. But azaleas demonstrate a certain independent spirit and ability to break the rules. As a result, you may notice last year’s white azaleas are mixed with some lavender branches, or your previously solid apricot azalea flowers are sporting stripes.

No, you’re not imagining things. Your azalea has thrown a sport, a genetic mutation that may correct itself the next growing season or be passed down to subsequent blooms. Some sports are highly prized by breeders and growers, and yours might be, too. If your azalea’s sport is especially interesting, you can save it by cleanly removing the branch and letting it root. Once roots grow, you can include the new plant in your collection of azaleas.

How to extend the azalea season

Azaleas are also categorized by their blooming seasons. Choosing azalea plants from each category can keep you in azalea flowers for most of the year. Here are just a few of the thousands of types of early, mid-season, and late bloomers.

Early varieties

  • Lilac-shaded spider azaleas
  • Soft pink coral bells
  • Bold Sherwood red

Mid-season varieties

  • Vibrant pink pride of mobile
  • Pastel-tinged white windbeam
  • Soft pink wheatley

Late-season varieties

  • Orange flame creeper
  • Peach-hued Weston’s lemon drop
  • Pink sweet September

If fading azalea flowers leave you feeling a little blue, plant Encore azaleas. They bloom once in the spring along with other azaleas and then a second time when other plants are losing their last spring flowers.

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