Shade Tolerant & Sun Tolerant RhododendronsShade Tolerant & Sun Tolerant RhododendronsMost rhododendrons and azaleas do best when planted in areas with partial shade. That means areas with trees that cast shade with sun filtering through, or areas which are in shade part of the day and sun part of the day. The presence of sun light assures a good bud set; plants in full shade frequently don't bloom and frequently grow tall and lanky. The presence of part shade helps the plants fight insects pests and disease. For example, the natural predators of rhododendron and azalea lace bugs do not thrive in full sun. Root rot is much more prevalent on plants where the roots can't be kept cool. Usually plants that are infected with lace bugs will do much better if moved to areas with more shade. Plants prone to root rot stay healthier in areas where the soil is cooler and has good drainage.
Rhododendrons and azaleas, which are among the most popular flowering plants for shade, are commonly thought to be, as a group, amenable to low-light conditions. In fact, all of them need some sun to produce the most profuse flowers, but some need more sun than others. In general, most Azaleas will grow very well if they receive four hours or more of bright sun per day. Rhododendrons will grow nicely in full sun to moderate shade. A few Rhododendron varieties such as 'Caroline', 'Scintillation', Yakushimanum hybrids, 'Hong Kong' and the hardy varieties from Finland must have some shade in midday or the foliage will yellow or even burn - especially during a hot summer. 'P.J.M.' and 'Nova Zembla' are two of the hardiest evergreen types.
Many varieties need shade to prevent lace bug infestations since the natural enemies of lace bugs are not active in sunny areas.
On the other hand, if shade is too dense, it can cause fewer blooms and spindly growth. Dense shade and poor air circulation can also be deadly to Rhododendrons. The combination frequently results in fungus which attacks new plant growth and eats away at the plant branch by branch. The species and hybrids listed here bloom especially well in the minimal sun and bright light of open to medium shade, and two of them, 'Snowlady' and the royal azalea, will even bloom in deep shade. Despite their physical differences, rhododendrons and azaleas belong to the same genus and require the same growing conditions. The rhododendrons are all evergreen; ten of the azaleas are deciduous and one is evergreen. [Return to Top]
'Boule de Neige' means “Ball of Snow” in French. As you might expect, the flowers are white, in perfect rounded trusses, and geometrically proportioned to the leaves. The habit is dome shaped. Leaves are matte green, and the plant’s constitution is tough and very hardy. It grows to a height of 4' and width of 5'. It even blooms well in deep shade. [Return to Top]
'Bow Bells' is a perfect mound of pink. The flowers are followed by shiny, copper colored new leaves. As the season progresses, the mound becomes a superb jade green with rose-red bud scales for another show of color. While growth at 10 years is 3', it will become a larger plant, so give it enough space. A site with filtered light is best for ´Bow Bells´. Fertilize lightly, as an excess of fertilizer will cause foliage burn more easily than on most rhododendrons. [Return to Top]
'Elviira' rhododendron is very hardy. It grows to a height of 2' and width of 18" to 24". It grows well in shade. A very low growing rhododendron cultivar. Densely branched, it is covered with flower buds that are hardy to -30F and open bright red. From the group of Marjatta hybrids developed at the University of Helsinki, Finland. [Return to Top]
'King George' is a tall hybrid rhododendron that blooms in mid-spring, producing huge pale pink flower clusters that turn white as they mature. It generally grows 6 feet tall but may reach a height of 12 feet. With rhododendrons, the rule of thumb is that the larger the leaf, the less sun they can handle gracefully. 'King George' and other Loderi rhododendrons are large leaf plants that follow this rule. However, if given enough shade they are also drought tolerant. [Return to Top]
'Nova Zembla' rhododendron has true hardiness in a red. A vigorous plant that has good foliage and will grow in more difficult areas. This hybrid exhibits some outstanding characteristics. Of course, hardiness tops the list. A nice looking contrast with other plants. Extremely showy, red flowers make a real display in the spring.. Dark red flowers in a ball-shaped cluster. Broad, bushy plant. Cold and heat tolerant and sun and shade tolerant. It grows to 5' tall and is hardy. [Return to Top]
'P.J.M'. hybrid rhododendrons. The 'P.J.M.' group of rhododendrons are smaller, growing to a height of 3 to 5 feet tall. Form is rounded and the foliage is leathery and dark green until fall when it turns almost purplish. One of the reasons the 'P.J.M.' group is such a heavy flowerer is that the plant does not set seed. They are very hardy, among the hardiest and most shade tolerant rhododendrons. They include the following:
'Ramapo' is a good dwarf rhododendron. It grows approximately 2 feet tall and 4 feet wide. Flowers are bright violet-pink. 'Ramapo' is hardy to -25°F. Tolerates sun and shade. [Return to Top]
'Red River' is a hybrid of a red flowered maximum. It has the late bloom and the large leaves of maximum. The flowers, larger than maximum's flowers, are bright red with a white throat and small yellow dorsal flare. A robust plant with an upright habit, it can be an open grower, but pinching will help and its habit gets better with age. Good for extending your bloom season into June. 'Red River' is hardy to -20°F. Tolerates sun and shade. [Return to Top]
'Snowlady' is a hybrid rhododendron that grows to a height of only 30 inches. It produces an abundance of snowy white flowers and has fuzzy green leaves. [Return to Top]
Rhododendron catawbiense, the Catawba Rhododendron, is an evergreen shrub that grows to a height of 6 or 10 feet tall and a width of 5 to 8 feet. Though unusual, some cultivars may reach 15 or 20 feet with age. Foliage is dark green and leathery, with oval leaves, lending a course texture to the landscape. Flowers range in color from lilac to rose with green or brown markings in the throat. This plant is very hardy. It is generally dense under ideal conditions, but becomes more open in dense shade. [Return to Top]
Rhododendron minus, the Carolina rhododendron, is a native American plant that grows wild in the Blue Ridge Mountains of North Carolina. It is 3 to 6 feet high with a naturally rounded shape and dark green leaves 3 inches long. In mid-spring it is covered with 3-inch clusters of rose-pink flowers. There is also a variety with pure white flowers and lighter green leaves, R. carolinianum 'Album'. It wants bright shade or dappled sunlight, but by no means deep shade. [Return to Top]
Rhododendron calendulaceum, the flame azalea, is a native American species, growing 4 to 6 feet high. It bears clusters of 2-inch clove-scented yellow to red-orange flowers in early summer, when most other azalea species have finished blooming. The leaves are 3 inches long and drop in the fall. Does best with partial shade. [Return to Top]
Rhododendron kuisianum, the Kyushu azalea, is a low-growing Japanese species, only 18 inches high. Its leaves are deciduous when the plant is young but evergreen in maturity, remaining on the plant all winter, though often changing color. In its original form the Kyushu azalea is covered in mid-spring with 8- to 10-inch clusters of lilac pink flowers, but there are many named hybrids derived from this species.
It prefers partial shade.
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Rhododendron schlippenbachii, the royal azalea, is a deciduous species, also of Japanese origin. It has soft green leaves that grow in whorls around the stem and turn yellow, orange and crimson in the fall. Its pink star-shaped flowers bloom in loose clusters in mid-spring and have a delicate fragrance. It needs shade from hot sun. Dappled shade or morning sun/ afternoon shade is necessary to protect the rather thin textured leaves from scorching. [Return to Top]
Other deciduous azaleas: Most deciduous azaleas do well in full sun and frequently are poor bloomers in the shade. "Maid in the Shade" deciduous azaleas is a collection of deciduous azaleas compiled by Transplant Nursery selected to do well in shadier locations. They include:
The larger rhododendrons and azaleas like 'King George' and flame azalea make excellent specimen plants or informal groups in woodland settings, while smaller plants, such as the Carolina rhododendron, flourish in the shade of arbors and trellises. 'Snowlady', and Kyushu azaleas can be used in the foreground of border plantings, and all three are also handsome pot plants for use in tubs or containers on shaded patios and terraces. [Return to Top]
Rhododendrons and azaleas are among the most popular flowering plants for shade. But most rhododendrons will grow nicely in full sun to moderate shade. A few Rhododendron varieties such as 'Caroline', 'Scintillation', 'Lee's Dark Purple', Yakushimanum hybrids, 'Hong Kong' and the hardy varieties from Finland must have some shade in midday or the foliage will yellow or even burn - especially during a hot summer. Others will become infested with lace bugs if raised in full sun. These varieties need shade to prevent lace bug infestations since the natural enemies of lace bugs are much less active in sunny areas.
To be useful in full sun, rhododendron and azaleas must 1) be lace bug resistant, 2) not be prone to sun scald, and 3) not be prone to root rot. These plants are also useful in partial shade but may have problems setting flower buds and blooming if the shade is too dense. Among the most sun tolerant plants are deciduous azaleas. Below are lists of other rhododendrons and azaleas that are generally considered sun tolerant. [Return to Top]
‘A. Bedford’ — 6’, -5F, ML, 4/3. This large growing, vigorous rhododendron tolerates exposure to full sun. Its funnel shaped flowers with ruffled edges are pale mauve to lavender-blue with a distinctive dark blotch. This is a good selection for a background plant. [Return to Top]
‘Alena’ — 5’, 10F, EM. Introduced from the Czech Republic, this sun tolerant plant has fragrant white flowers with yellow spotting in the throat. There will be a slight blush on new flowers. Dark glossy leaves cover the broad, mounding plant. [Return to Top]
‘Anah Kruschke’ — 6’, -15F, ML-L. A good looking rhododendron that grows well in sunny, hot locations. Its reddish-purple flowers are held in medium sized, tight trusses. Dense and lush foliage with dark green leaves. [Return to Top]
‘Aunt Martha’ — 5’, -10F, M-ML. Hardy, vigorous, densely foliated and heavy blooming plant. Plenty of leathery leaves enable the plant to grow well in full sun and moderate heat. Bright red-purple flowers are speckled with gold in the center. [Return to Top]
‘Barto Alpine’ —3’, -10F, EM. Orchid-rose flowers open all along the stems of the densely branched plant. It has the spicy scent of freshly ground nutmeg. Its dense upright growth habit is a form well-suited for planting as a short hedge or screen reaching 5’. [Return to Top]
‘Belle Heller’ — 5’, -10F, M. Here is hardiness, sun tolerance, lush foliage, and a lovely flower all in one. The large flower is pure white with a striking gold blotch, set in large, ball shaped trusses on a vigorous grower. [Return to Top]
‘Black Eye’ — 5’, -10F, ML. A sister seedling of ‘Red Eye’, this rugged plant stands sun well and blooms young. The deep red-purple flowers have a distinct "black eye" on the upper lobe. [Return to Top]
‘Blue Angel’ — 6’, -15°F, M. It has lovely purple flowers with a contrasting yellow blotch. With strong green, sun tolerant, foliage the growth habit is much like its parent. [Return to Top]
‘Blue Diamond’ — 3’, -5F, EM. A favorite of many gardeners, ‘Blue Diamond’ has small flowers all along the vertical dense, finely branched stems. A sunny location is best for this well shaped plant often used in a border. [Return to Top]
‘Blue Ensign’ — 4’, -15F, M. Very hardy, sun tolerant, lilac blue with a striking purple blotch. Its truss is similar to ‘Blue Peter’ and while they both become huge plants, ‘Blue Ensign’ is more compact. [Return to Top]
‘Blue Peter’ — 4-5’, -10F, M. Its frilled flowers are light lavender-blue with a prominent purple flare. The lush leaves are glossy green. It’s vigorous, cold hardy, heat and sun resistant. [Return to Top]
‘Cadis’ — 5’, -15F, ML. With long, narrow leaves and the fragrant, light pink trusses, this plant is a popular cold hardy hybrid from the eastern U.S. A sun tolerant selection. [Return to Top]
‘Cheer’ — 5’, -10F, EM. Pink trusses signal the coming of spring. Plenty of glossy, dark green leaves dress ‘Cheer’. Plant grows compactly forming a dense, round mound. [Return to Top]
‘Cherries ‘n Cream’ — 4’, 5F, M. A new plant with exceptional foliage. Sun tolerant and compact in growth habit, this plant sports large pink flowers that open from cherry-red buds. [Return to Top]
‘Chionoides’ — 4’, -10F, ML. Tolerant of the sun and cold, this compact hybrid grows beautifully even when planted in locations often considered too exposed for a rhododendron. A broad, dense cushion measuring 5-6’ high develops as the plant matures. White, dome trusses are bright and numerous. [Return to Top]
‘Christmas Cheer’ — 4’, -10F, VE-E. Extremely early pink trusses. Tough, medium sized leaves are dense on this well shaped plant. It doesn’t bloom at Christmas time as the name might indicate. [Return to Top]
‘County of York’ — 6’, -15F, M. Vigorous growing plant with large, upright white trusses of good substance. Here is hardiness, good flower and large foliage, all in one hybrid. Apple-green, somewhat shiny foliage. Sun exposure and cold are well tolerated. [Return to Top]
‘Crater Lake’ — 4-5’, -5F, EM-M. Flowers are electric blue, flat and saucer shaped, with ruffled edges. They are held in groups of three, with many on a single branch. New foliage is bronze, changing to green with maturity. [Return to Top]
‘Cream Crest’ — 3’, 0F, EM. Compact in habit, it likes the sun, has good foliage, is hardy and vigorous, and has alluring, bright, creamy yellow flowers. [Return to Top]
‘Cynthia’ — 6’, -15F, M, 4/3. An old favorite which is still one of the best for a strong growing, background plant. ‘Cynthia’ will produce a bounty of large, conical, rosy-crimson trusses. Sun and heat tolerant. [Return to Top]
‘Daphnoides’ — 4’, -15F, ML. Rolled, glossy leaves are tightly spaced on the stems of this dense mound. Prolific pom-pom trusses are purple. [Return to Top]
‘Dora Amateis’ — 3’, -15F, EM. Pure white flowers cling to this low growing, bushy plant. Its deep green, dense foliage is highlighted with bronze tones and is prettiest when grown in full sun. It is a spicy scented hybrid with great foliage. [Return to Top]
‘Fastuosum Flore Pleno’ — 6’, -15F, ML. Double, lavender-blue flowers with a large golden flare on the upper dorsal lobe give extra interest to this hardy, sun tolerant hybrid. The growth habit is somewhat open but round on this fine plant. Its good foliage is dense and green. [Return to Top]
‘Gomer Waterer’ — 6’, -15F, ML. This old standby is one of the best whites ever hybridized. Flower buds are a delicate pink that open to blush white blossoms containing a freckling of soft green in the throat. Large deep green leaves make this an outstanding foliage plant. Very sun tolerant. [Return to Top]
‘Hallelujah’ — 4’, -15F, M. The leaves are a deep green, extremely heavy textured and have an attractive, downward curving form. The flowers are rose-red in a large, tight truss. It’s an adaptable rhododendron. [Return to Top]
‘Hardijzer Beauty’ — 3’, -5F, EM. A dwarf evergreen azaleodendron from Holland. This small plant is vigorous and sun tolerant. When in flower, clear pink blossoms open all along the stems. It is an excellent choice for a small bed or long, low border. [Return to Top]
‘Jean Marie de Montague’ — 5’, -5F, M. Every new red introduced is judged against ‘Jean Marie’ (as it is often called) to see if it is better and few actually pass the grade. ‘Jean Marie’ has bright red flowers so showy that you can’t miss them. The thick, heavy foliage stands sun and is deep emerald-green. Few plants have foliage as green. Buds young. [Return to Top]
‘Jock’ — 3’, -5F, EM. Rosy-pink flowers are everywhere upon this rolling mound of green. The plant gives best results in full sun and is easily rooted. [Return to Top]
‘Lady Clementine Mitford’ — 5’, -5F, ML. A hardy plant with distinctive gray-green leaves. The flowers are beautiful, soft peach-pink. Its foliage looks like it was sprinkled with silver. Can withstand both sun and heat. Also known as ‘Lady Clementina Mitford’. [Return to Top]
‘Manitou’ — 3’, -25F, EM. This new hybrid is similar to‘Windbeam’, only it is more compact in growth habit. It covers itself with luscious light pink flowers from top to bottom. Its small leaves will stand sun and makes a plant to be admired in the garden. [Return to Top]
‘Mrs. Charles E. Pearson’ — 6’, -5F, M. Flowers are light pink with brown spots. It was developed in 1909, received an Award of Merit in 1933 and then a First Class Certificate as late as 1955. Super vigorous with lush foliage. Sun and heat tolerant. [Return to Top]
‘Mrs. G. W. Leak’ — 6’, 0F, EM. Tall, vigorous plant with olive-green leaves. Clear, light pink flowers have a dark blotch in an upright compact truss. Grows in sun or shade. [Return to Top]
‘Myrtifolium’ — 3’, -15F, L. For heat and sun tolerance this is extremely good. This plant has beautiful deep bronze-red foliage all winter and is a joy to view. It flowers very late in the season with small, medium pink flowers, great to extend the flowering time of rhododendrons. The plant is dense and well clothed in leathery leaves that are a rich, matte green in summer. A dependable rhododendron. [Return to Top]
'Nova Zembla' — 5 ’, -25F, M. This rhododendron has true hardiness in a red. A vigorous plant that has good foliage and will grow in more difficult areas. This hybrid exhibits some outstanding characteristics. Of course, hardiness tops the list. A nice looking contrast with other plants. Extremely showy, red flowers make a real display in the spring.. Dark red flowers in a ball-shaped cluster. Broad, bushy plant. Cold and heat tolerant and sun and shade tolerant. [Return to Top]
‘Oceanlake’ — 30", -5F, EM. Deep violet-blue flowers make a charming display on this small-leafed hybrid. The foliage turns interesting tones in winter. Will take sun. [Return to Top]
‘PJM’ — 4’, -25F, E. This hybrid is cold hardy as well as tolerant of heat and sun as well as shade. Its small, rounded leaves are green during the summer and mahogany colored in winter. ‘PJM’s’ early bright lavender-pink flowers are beautiful against its dark colored winter foliage. One of the reasons the 'P.J.M.' group is such a heavy flowerer is that the plant does not set seed. They are very hardy, among the hardiest and most sun tolerant rhododendrons. They include the following:
‘Ramapo’ — 2’, -20F, EM. Plentiful pale violet flowers are amid a bushy blue-green mat of leaves. This hardy dwarf can be grown in sun or partial shade, although in full sun it will maintain a more compact form. It is well suited for use in a low border or rock garden. [Return to Top]
‘Red Eye’ — 5’, -10F, ML. This plant stands sun, buds young, branches readily and does not mind heavy cutting for propagation! It’s a plant you can depend on year after year. The flowers are deep red-purple with an interesting eye. When the flower first opens, the eye is green gold and little by little it becomes red. It is an interesting contrast with the purple! ‘Red Eye’ is a misnomer because the "eye" isn’t always red. [Return to Top]
‘Rose Elf’ — 18", 5F, E. Often there are six or eight flower buds per stem which open to a delightful pastel orchid pink. Jade green leaves are numerous along this bushy multiple stemmed plant. In full sun exposure the leaves take on a bronze cast. ‘Rose Elf’ forms a bushy low border. It is well suited also to rock gardening and bonsai culture. [Return to Top]
‘Scarlet Wonder’ — 2’, -15F, M. ‘Scarlet Wonder’ is a low, exceptionally compact plant with dense glossy green leaves that have an interesting texture. The plant will stand more sun and exposure than most. This is a great foliage that plant, that, when it blooms, turns into a mass of brilliant scarlet red. [Return to Top]
‘Sonata’ — 3’, 0F, L. ‘Sonata’ has tubular shaped, orange-red flowers edged in red. The mass of slender, dark green leaves do well in a sunny spot. [Return to Top]
‘Trilby’ — 5’, -15F, ML. Beautiful flowers of deep crimson with black marking. Matte green leaves are set off against red stems to beautify the plant even when not in flower. Sun tolerant. [Return to Top]
‘Wissahickon’ — (parentage unknown) 5’, -15F, ML. A good choice if you are looking for a vigorous growing variety that is sun tolerant. The bright rose flowers, with a deeper throat, have brownish spotting. A plant of good reputation in the East. [Return to Top]
‘Wyandanch Pink’ — 5’, -15F, M. This is the rhododendron for that sunny spot in the yard as it does best in the sun. Excellent foliage highlight the vivid pink flowers spotted darker on the upper lobe. [Return to Top]
‘Yellow Hammer’ — 4’, 5F, EM. Very deep yellow flowers are held on an upright growing plant. Can be trimmed easily and makes a good hedge. One of the few yellow rhododendrons that will do well in sunny locations. [Return to Top]
For a list of hybrid rhododendrons good for sun and heat visit Hybrid Rhododendrons for Sun and Heat.
Rhododendron racemosum — 2-5’, -5F, E-EM. Does well in sunny locations. It grows many erect red stems lined with glossy round leaves. Pink flower buds occur along upper portions of the stem and in multiples at stem tips. Fairly early in the flowering season, R. racemosum will appear as a bundle of clear pink plumes. [Return to Top]
Rhododendron augustinii ssp. augustinii — 6’, 5F, E-M. The smooth leaves, small, long, and dark green, have densely scaled undersides. It’s a strong grower and flowers in abundance, a radiant blue color not to be forgotten. [Return to Top]
Rhododendron augustinii ssp. chasmanthum — 6’, 5F, E-M. Flowers are widely funnel shaped giving then tighter trusses and are typically later than R. augustinii. Leaves are often wider and can be partly deciduous. A good, strong grower with excellent sun tolerance. [Return to Top]
Rhododendron hippophaeoides var. hippophaeoides —3’, -25F, E. The hardiest plant of the species, this variety withstands frost even when in flower. It is also tolerant of sun and swampy conditions. The flowers are lavender-blue. [Return to Top]
Rhododendron impeditum — 1’, -15F, EM. One of the best dwarf rhododendrons, this species has a tight compact habit with attractive silver-gray foliage. Bright blue-purple flowers make a nice contrast. Planted about 15" apart, a number of plants will grow together to form an impenetrable ground cover, handsome at all seasons and especially effective when such an expanse becomes a blanket of blue flowers." [Return to Top]
Rhododendron lutescens — 6’, 5F, EM. Sunny yellow flowers bloom amidst bronzy red foliage. Open and upright, the new growth is bright red, and creates quite a display in itself. The medium sized leaves, which range in color from dull dark green to a lovely bronzy red, are oblong or lance shaped. Very sun tolerant. [Return to Top]
Rhododendron trichostomum — 30", 0F, M. Numerous small, tubular flowers will last for a month. The succulent flowers are a clear light pink, resembling the flowers of daphne more than rhododendron. A sunny location has proven to be best. [Return to Top]
‘Autumn Amethyst™’ — -10F, Low/Med. This lavender is one of the Encore® reblooming azaleas. [Return to Top]
‘Autumn Cheer™’ — -10F, Low. This pink is one of the Encore® reblooming azaleas. [Return to Top]
‘Autumn Rouge™’ — -5F, Low/Med. This bright pink is one of the Encore® reblooming azaleas. [Return to Top]
‘Autumn Royalty™’ — -10F, Med. This purple is one of the Encore® reblooming azaleas. [Return to Top]
‘Autumn Sangria™’ — -10F, Med. This dark pink is one of the Encore® reblooming azaleas. [Return to Top]
‘Autumn Twist™’ — -10F, Med. This white with purple markings is one of the Encore® reblooming azaleas. [Return to Top]
‘Deciduous Azaleas’ — Most deciduous azaleas are hardy to -25°F, grow well in the sun and really can be grown practically anywhere. They frequently are poor bloomers in the shade. [Return to Top]
‘Flame Creeper’ — Late, -10F, Dwarf. Noted for its tolerance of full sun, this reliable azalea displays a profusion of scarlet-orange flowers. It makes a good ground cover with its small leaves and creeping habit. [Return to Top]
‘Hino Crimson’ — Early, -10F, Low/Med. Bright crimson flowers unfold in April, and holding their color well. This attribute, coupled with sun tolerance and red winter foliage, makes ‘Hino Crimson' an excellent all around choice. Planted in the open, it grows to a dense 2½' mound, although it adapts well for use as hedging. [Return to Top]
‘Hinode-giri’ — Early, -5F, Medium. One of the more sun-tolerant hybrids, this azalea produces multitudes of rose-crimson flowers early to mid-season. Small, glossy leaves turn bright red in winter on this dense plant. [Return to Top]
‘Stewartstonian’ — Early, -20F, Medium. A sun tolerant hybrid, ‘Stewartstonian' displays lush red 2" blooms that, in the light, appear blood orange. Winter foliage deepens to wine red, making it an excellent winter foliage plant. [Return to Top]
Royal azalea is hardy in Zones 4-8, to -25° F; flame and Kyushu azaleas and Carolina rhododendron in Zones 5-8, to -15° F; and 'King George', 'Snowlady' and R. williamsianum in Zones 7 and 8, to +5° F.
All rhododendrons thrive in a cool, moist, acid soil. Plant them in spring or fall where winter damage is no hazard; otherwise, plant them only in spring, setting the balled-and-burlaped root balls in the soil no deeper than 12 inches. Do not fertilize at the time of planting, as this might injure the roots, but water deeply. Supplemental feeding later is not normally needed, but if a plant appears pale or droopy, apply cottonseed meal or a fertilizer for acid-loving plants around its base in early spring. A year-round mulch of rotted oak leaves will also provide natural nutrients and will help keep the soil cool and moist.
Do not cultivate around the shallow roots of rhododendrons and azaleas, but pinch off their faded flowers to improve bloom the following year. Also, prune out dead, diseased or damaged branches, and cut old branches back to the soil level to encourage new growth.
Rhododendrons may be propagated from stem cuttings of new growth taken in late summer and rooted in a mixture of perlite or vermiculite and peat moss. For deciduous azaleas, cuttings may need bottom warmth of 75° and artificial light to promote root growth.
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