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How to Grow: Deciduous Azalea
part sun, part shade
Bloom Period and Seasonal Color
Early spring in colors such as pink, salmon, yellow, white, rose and bi colors
Mature Height x Spread
4 to 8 feet x 4 to 8 feet
Attracts beneficials, fall color, deer resistant
Azaleas are in the rhododendron family and usually distinguished from other rhododendrons by their smaller plant size. There are deciduous and evergreen azaleas. Evergreen azaleas are not as hardy as deciduous types. You’ll find these growing well in more southern climates. They are not reliable throughout New England. Deciduous azaleas are more winter hardy. They flower in early spring, before the leaves emerge, with brilliant flower colors turning a woodland or landscape into a flower show. Deciduous azaleas look best grouped together as understory plants or planted in a partly shaded area of your yard. After the amazing spring flower show the dark green foliage makes an excellent backdrop for other flowering shrubs and perennials.
When, Where and How to Plant
Deciduous azaleas are hardy to zone 4, so grow well in most parts of New England. Purchase plants from a local garden center and plant from spring to early fall in a partly shaded location on well-drained, humus-rich soil with a low pH. Space plants 4 to 6 feet apart.
Deciduous azaleas are shallow-rooted and need an acidic soil, high in organic matter, to grow and flower best. Amend the soil with sulfur in spring to lower the pH to around 5. Keep plant well watered and mulch with pine needles, peat moss or bark mulch to keep the soil cool and moist and keep the pH low. Fertilize in spring with an azalea or rhododendron plant food. Don’t fertilize after July 1st or it may delay dormancy leading to winter injury.
Regional Advice and Care
Deciduous azaleas can grow well in a sunny location in northern areas as long as they have consistently moist soil. In colder areas, or along the coast, they need protection from the cold, winter winds. Place four stakes around plants and wrap burlap around the stakes to protect your azaleas. Prune after blooming to shape the plants. Remove dead or diseased branches any time. Deciduous azaleas can be attacked by scale insects. Spray a dormant oil spray on branches in late winter before the flowers emerge to kill overwintering insect eggs.
Companion Planting and Design
Plant deciduous azaleas grouped in a woodland setting with filtered light, grown under high-canopied oaks or maples, or in a landscape. Azaleas pair well with evergreens such as rhododendrons and cedars, and with other spring flowering shrubs such as forsythia.
The ‘Exbury Hybrid’ deciduous azaleas are probably the most common type in New England. They have an upright, vase shape and bloom in a variety of warm colors such as orange, red, and peach. Some varieties have bi colored blooms as well. The ‘Northern Lights’ azaleas were bred in Minnesota so are very hardy. They are more compact shrubs with bloom colors such as pink, white gold, and salmon.
Excerpted from my book, New England Getting Started Garden Guide.