Gardening with Azaleas

Rhododendron 'Hinode-giri' (Kurume Hybrid)
Azalea ‘Hinode-giri’ (Kurume Hybrid) is a bright selection for spring. (Photo by Jessie Keith)

A single azalea, cloaked in bright petals, is the essence of spring. Grouped together, these versatile shrubs make an elegant tapestry in semi-shaded areas of the garden. With single or double flowers in white, shades of pink, red, purple, yellow and orange, the artistic possibilities are unlimited. Achieving great garden effects with one or more of the many azalea species and varieties requires little more than knowledge of their basic cultural requirements, a bit of garden or container space, and imagination.

Azalea Basics

Rhododendron 'Josephine Klinger' (Ghent Group)
The sunset flowers of azalea ‘Josephine Klinger’ (Ghent Group) offer luscious springtime color. (Photo by Jessie Keith)

All azaleas belong to the rhododendron genus and have Latin names that begin with the word “rhododendron.” So do their close relatives, the ornamental plants that go by the common name, “rhododendron.” This can cause confusion for novice azalea buyers. Fortunately, differences between azaleas and rhododendrons are fairly easy to spot, even if plant tags are missing. Azaleas are generally small-leafed deciduous or evergreen shrubs with loose clusters of fragrant, funnel or trumpet-shaped flowers. Rhododendrons are most often evergreens with larger leaves and fat trusses of bell-shaped blooms.

Azalea Cultural Requirements

A mature azalea–which can grow anywhere from two to eight feet tall–may look big and strong, but its roots are shallow and need consistently moist, well-drained soil that is on the acid end of the pH spectrum. If you are not sure about your soil chemistry, use a soil test kit, available at nurseries and garden centers, to find out. If soil is neutral or alkaline, amend with a product like Fafard Sphagnum Peat Moss to help increase acidity. Preserve soil moisture by mulching azaleas with at least two inches of organic material, spread in a two-foot radius around the base of each plant. If pruning is needed, do so immediately after flowering.

Azalea Stars for Shade

Pink Rhododendron canescens
The palest pink flowered mountain azalea (Rhododendron canescens) is a great native for the garden. (Photo by Jessie Keith)

In the wild, azaleas are natural understory plants that thrive in light shade. This trait makes them perfect for the semi-shaded or woodland garden, where the colorful blooms lighten things up in mid to late spring. If you have room, plant varieties like fragrant, pink ‘Candy Lights’ in groups of three for a dramatic impact. Underplant azaleas with spring bulbs for early interest and install hosta varieties for color and texture later on. Add foliage color by using a variegated azalea such as the semi-evergreen ‘Bollywood’, featuring green leaves edged in cream.

Native Azaleas

Native azaleas, including the fiery golden-orange flame azalea (Rhododendron calendulaceum) and pale pink flowered mountain azalea (Rhododendron canescens), make excellent additions to native plant gardens. The blooms attract butterflies and hummingbirds, while the fragrance lures human admirers. Place close to paths or seating areas to take advantage of the scent. For a succession of bloom and three-season interest, try combining flame azalea with another native shrub, oakleaf hydrangea (Hydrangea quercifolia), which bears white flower panicles that age to pink and oak-like leaves that redden in the fall.

Container Azaleas

Glenn Dale azaleas at U.S. National Arboretum. (Photo by Tim McCabe, USDA)
At the U.S. National Arboretum, Glenn Dale azaleas flourish. (Photo by Tim McCabe, USDA)

Bloom-a-Thon ‘White’, which tops out at 36 inches tall, is typical of smaller azaleas that work well in large containers. The Bloom-a-Thon and Encore series, like other compact, reblooming varieties, have the added bonus of flowering once in mid-spring and again in early summer, with the possibility of an additional flush of bloom in early fall. For a continual feast of flowers, underplant containers of reblooming azaleas with New Guinea impatiens in complementary or contrasting colors. Containerized azaleas benefit from the good nutrition and water retention provided by a quality potting medium like Fafard Natural and Organic Potting Soil.

Azalea Colors

Sometimes azalea lovers get carried away with color, planting magenta, orange and pink varieties close together. While this may stop traffic in the neighborhood, it also tends to create visual chaos. Make the landscape more coherent by choosing one color or color range, such as pinks. If there is room, plan for a succession of bloom by planting an early blooming azalea, like pink-flowered ‘Camilla’s Blush’ and a later flowering specimen in the same color range. ‘Weston’s Lollipop’ is one example. Underplant with perennials and annuals in the same hue. For a sophisticated finish, add a few contrasting companion plants in a shade that is on the opposite side of the color wheel. ‘Lime Green’ flowering tobacco (Nicotiana alata), for example, makes a perfect foil for a pink planting scheme.