Florida flame azalea (Rhododendron austrinum).
Joey Williamson, ©2013 HGIC, Clemson Extension
Among the most beautiful of South Carolina’s native flowering shrubs are the native azaleas. Gardeners in all parts of the state can enjoy the spectacular flowers and delightful fragrance of many of these eastern native shrubs.
There are numerous native azalea species in South Carolina, with bloom times from early spring through late summer. The flower colors range from white to many shades of pink, red, yellow, orange and salmon. These deciduous shrubs (that is, they lose their leaves during the winter) are members of the genus Rhododendron, which also includes the evergreen azaleas and rhododendrons. Mature plant sizes vary from two-foot tall spreading species to 15 foot tall tree-like shrubs.
Popular choices include the Florida flame azalea (Rhododendron austrinum), which blooms in April with orange, yellow or scarlet flowers. This magnificent species is certainly one of the showiest of the native azaleas.
The piedmont azalea (R. canescens) is one of the earliest bloomers and begins its show with pale pink flowers in early April. ‘Camilla’s Blush’ is a selection with ball-shaped trusses of soft pink blossoms, and grows to eight feet.
Piedmont azalea (Rhododendron canescens).
Joey Williamson, ©2013 HGIC, Clemson Extension
The sweet azalea (R. arborescens) has white blooms, dark green foliage and is very fragrant. This June bloomer usually needs relatively moist soil. This species will grow to six to eight feet.
The flame azalea (R. calendulaceum) flowers in May and typically has large orange blooms, but again, colors vary widely. ‘Kelsey’s Flame’ is an outstanding cultivar with striking yellow and orange flowers, and grows to eight to ten feet.
Other native azaleas available include the coastal azalea (R. atlanticum), the pinxterbloom azalea (R. periclymenoides), the swamp azalea (R. viscosum) and numerous cultivars of crosses between the native azaleas. These crosses have added to the many color variations and color combinations naturally present in our native azaleas.
From a landscaping perspective, these native species can be grouped by flower color: white, pink or orange. However, considerable variation in flower color occurs within each species, and nurserymen have selected those with the most stunning colors. Recently, more garden centers in South Carolina offer native azaleas for sale, including many cultivars and hybrids of these species that have been selected for superior flower color. For more information on the native azalea species, see Table 1 below. Table 2 below lists examples of selections and hybrids of the Southeastern native azaleas often available for sale. For photos of the many species and cultivars, please see HGIC 1058, Azaleas.
Landscape Site
Flame azalea (Rhododendron calendulaceum).
Joey Williamson, ©2013 HGIC, Clemson Extension
Native azaleas prefer cool, partially shaded sites with rich, moist woodland soil. But exceptions occur as some will tolerate dry woodland soil, and others flourish in what would be considered excessively moist areas. They can be planted any time of the year, but greater success may be obtained with an autumn planting. However, spring is usually the time these shrubs are found at the garden centers.
When choosing a site for a native azalea, morning sun and afternoon shade will be best. In general, species that flower in June or later may require more shade, as the delicate flowers will not tolerate the hot summer sun. For overall plant health, adequate soil moisture can help compensate for the excessive summer heat.
Soil Preparation & Planting
Native azaleas prefer acid soils with a pH 5.2 to 5.8, and most South Carolina soils are naturally acidic. Unless directed by a soil test to add lime to the soil, you should not lime the soil near these plants, because their foliage may become yellow or chlorotic.
At planting, it’s always best to loosen and prepare the soil in large planting beds, rather than individual holes. One of the best forms of organic matter to incorporate with the existing soil is composted pine bark, which is naturally acidic. These shrubs must be planted at the same level in the soil as they were in the container, or slightly higher if the soil is poorly drained.
Be sure to mulch the plants with a three-inch thick layer of pine bark, pine needles or leaves to help keep the soil cool and to conserve soil moisture. However, the mulch should not be piled against the stem or trunk of the plants. Then be sure to water the plants well initially to settle the soil. Remember that until a plant is established, it is dependent upon the homeowner for water. They will need to be watered weekly during the first growing season if there is insufficient rainfall.
Fertilization
Fertilize native azaleas lightly in the spring and early summer with a well-balanced, extended-release, acid-forming, azalea fertilizer. By well-balanced, this means to look for nutrients in the ratio of 2-1-1. Never fertilize azaleas in the late fall with these high nitrogen fertilizers, as this may delay dormancy and result in plant injury.
Fertilizer examples are:
- Lilly Miller Rhododendron, Evergreen & Azalea Food (10-5-4)
- Lilly Miller Ultra Green Azalea, Camellia & Rhododendron Food (10-5-4),
- Sta-Green Azalea, Camellia & Rhododendron Food (10-5-4),
- Pennington UltraGreen Azalea, Camellia & Rhododendron Plant Food (10-6-8)
- Vigoro Azalea, Camellia & Rhododendron Food (10-8-8),
- Scotts Evergreen, Flowering Tree & Shrub Fertilizer (11-7-7).
Complete, acid-forming organic fertilizers are also excellent choices for use on azaleas, and these are great to mix into the soil at planting, as well as for use with spring fertilization. They are typically not as nutrient rich, and because of both the low nitrogen content and inability to burn the roots, they can be used to mix lightly into the soil in the fall at planting. Organic acid-forming fertilizer examples are:
- Espoma Holly-Tone (4-3-4),
- Fertrell Holly Care (4-6-4),
- Jobe’s Organics Azalea, Camellia & Rhododendron Fertilizer (4-4-4),
- Jobe’s Organics Holly Food (5-4-3)
- Natural Guard & Organic Azalea, Camellia, Rhododendron Food (4-3-4)
- Burpee Natural & Organic Azalea & Camellia & Rhododendron Plant Food 4-3-3
With proper site selection and planting, you will be pleasantly surprised at how well they perform and pleased with their exceptional beauty. For additional information on planting procedures for shrubs, please see HGIC 1052, Planting Shrubs Correctly.
Table 1. Native Deciduous Azaleas of the Southeastern US.
| Native Azalea Rhododendron Species | Flower Color | Bloom Time | Plant Size | Comments |
| R. alabamense Alabama Azalea |
Snowy white flowers with a prominent yellow blotch | Mid-April- May | Low to medium, 2 – 6’ | Spreads by stolons. Native to GA, AL, TN & FL panhandle. Distinct lemon-spice fragrance. Propagates easily from cuttings. |
| R. arborescens* Sweet Azalea |
White to blush pink flowers with red stamens | Early May – June | To 15’ | Native from AL to PA primarily along Appalachians, especially near streams. Very strong fragrance. Easy to propagate. |
| R. atlanticum* Coastal Azalea |
White flowers are often blushed with pink – some with a yellow blotch | Early April – May | Low,
1 – 5’ |
Native from GA through NJ along the coast. Spreads by stolons. Easy to propagate. Fragrant. |
| R. austrinum Florida Flame Azalea |
Shades of orange through gold and yellow. No blotch. The tube of the flower is often flushed with red. Very long stamens | Late March – April | To 15’ | Native to lower AL, GA & FL panhandle. Fragrant. Heat tolerant. Easy to propagate. |
| R. calendulaceum* Flame Azalea |
Wide range of colors from clear yellow, through shades of orange, to brilliant red | Early May – June | To 12 – 15’ | Native in Appalachians & piedmont from GA to WV. Large flowers. Difficult to propagate from cuttings. |
| R. canescens* Piedmont Azalea |
Shades of pink to white with no blotch. Long stamens | Late March – April | 10 – 15’ | Native over lower Southern states. Fragrant. Easy to propagate. |
| R. eastmanii* Eastman’s Azalea |
White flowers with yellow blotch & red stamens | May | Native in SC only; less common. | |
| R. flammeum* Oconee Azalea |
Shades of yellowish orange, through orange to deep red. Flowers usually have a blotch. | Early-April – early May | Variable | Native in SC & GA. Heat tolerant. Not fragrant. |
| R. periclymenoides* Pinxterbloom Azalea |
White to pale or deep pink flowers. Long stamens. | Mid-April- mid-May | 3 – 8’ | Native from AL through New England. Slightly fragrant. Moderate to easy to propagate. |
| R. prunifolium Plum Leaf Azalea |
Orange to vivid red flowers | Late June- July, or later | To 15’ | Native to AL & GA. Easy to propagate by cuttings & from seeds. Not fragrant. |
| R. vaseyi Pinkshell Azalea |
Delicate pink to white flowers | April | To 15’ | Native to mountains of NC. Less common. |
| R. viscosum* Swamp Azalea |
Flowers white, sometimes pinkish tinge. | Mid-May- June | 3 – 15’ | Spicy fragrance. Tolerates damp or wet soil. Spreads by stolons. Easy to propagate. |
| *Native populations exist within South Carolina | ||||
Table 2. Examples of Selections and Hybrids of Native Deciduous Azaleas.
| Cultivars of Hybrid Native Azaleas | Flower Color | Bloom Time | Plant Size |
| ‘Camilla’s Blush’ | Soft pink flowers; fragrant. | Early April | 8’ |
| ‘Darlin’s Dream’ | White flowers with lavender-pink edging and golden yellow throat. | Mid-April | 10 – 12’ |
| ‘Firecracker’ | Intense orange flowers with a touch of red; very fragrant. | April | 8’ |
| ‘Kelsey’s Glow’ | Bright yellow flowers with reddish hues. | Mid-April | 10 – 12’ |
| ‘Kennell’s Gold’ | Golden yellow flowers; fragrant. | Early April | 12 – 15’ |
| ‘Lisa’s Gold’ | Bright gold flowers. | Early April | 10 – 12’ |
| ‘Lucky Lady’ | Vibrant red flowers with peachy centers. | Mid-April | 6 – 8’ |
| ‘My Mary’ | Pure yellow flowers; fragrant. | April | 8’ |
| ‘Nacoochee Princess’ | Large, slender white flowers with tinge of pink; fragrant | April | 8 – 10’ |
| ‘Rosy Pink Nudiflorum’ | Pink flowers – rose in bud. | Early April | 6 – 8’ |
| ‘Rushin’s Austrinum’ | Bright yellow flowers with clear yellow tubes; very fragrant. | Mid-April | 8 – 10’ |
| ‘Sautee Sunset’ | Peachy-pink flowers with soft yellow throat. | Mid-April | 6 – 8’ |
| ‘Summer Eyelet’ | White flowers; spicy fragrance. | July | 6’ |
| ‘Tangerine Delight’ | Bright orange flowers. | Late April | 10’ |
Pesticides are updated annually. Last updates were done on 6/19 by Joey Williamson.
Originally published 02/14
