This past fall we received a question about over-wintering a Satsuki Azalea. She is an Oregon State University Master Gardener and Master Naturalist and holds a Master of Fine Arts in creative nonfiction writing. The leaves are spirally arranged; leaf size can range from 1–2 cm (0.4–0.8 in) to over 50 cm (20 in), exceptionally 100 cm (40 in) in R. sinogrande. They grow between 1.5-4" long. Broadleaf evergreen upright shrub, dense or leggy, about 4 ft (1.2 m) in 10 years, it can grow into a small tree, in the wild it may attain a height of 25 ft (~7.5 m). The Rhododendron genus contains about 1000 species, of which especially the Satsuki azalea (Rhododendron indicum) and Kurume azalea (Rhododendron kiusianum and Rhododendron kaempferi) are commonly used for Bonsai. Although too much shade results in sparse, leggy growth, too much sun may scorch or bleach the foliage. One potential Rhododendron problem is that the leaves are turning yellow. Although rhododendron leaves tend to curl during cold weather, it may not always protect them from winter burn. Tsutsusi Sweet, type Rhododendron indicum. M.H. There are hundreds of azalea cultivars. General Information: The azalea is a member of the genus Rhododendron. Leaves are oblong or elliptic-lanceolate, 10-20 cm long and 2.5-64 cm wide, dark green above, paler below; petiole 1.3-2.5 cm long. Bearing, robustness and vigor: shrubby species; grows up to 2 m. in height and diameter. Lanceolate to oblanceolate, slightly toothed leaves (to 1.5” long) are glossy dark green above and paler beneath. If the same symptom appears in new leaves, then it is likely … They weren’t sure how to ta Poor drainage inevitably leads to root rot, therefore raised beds/plantings should be considered in heavy clay soils such as those present in much of the St. Louis area. Lanceolate to oblanceolate, slightly toothed leaves (to 1.5” long) are glossy dark green above and paler beneath. © Copyright 2020 Hearst Communications, Inc. Leaves narrowly oval, occasionally somewhat obovate or lanceolate, about 1 in. Our body can break the toxin down when it's ingested in small quantities, which also limits its effects. Distribution and habitat:Rhododendron simsiiis native to East Asia, where it grows at altitudes of 500–2700m (1600-9000 feet). As it decomposes, mulch enriches the soil and helps to maintain the proper pH. Dyer began her writing career as a staff writer at a community newspaper and is now a full-time commercial writer. Rhododendron arboreum is an evergreen Shrub growing to 12 m (39ft) by 3 m (9ft). Most animals avoid it. wide, bright green above, somewhat scaly beneath, the margins crenulate, fringed with bristles. Evergreen azalea is a dense, naturally shapely plant that requires little pruning. The showiest of all spring flowering plants, rhododendrons will produce a wealth of beautiful colourful blooms. Commonly known as evergreen azalea, Rhododendron indicum is an attractive shrub with shiny, deep green leaves that display a hint of red during the winter. ‘Macrantha’ is a commonly sold cultivar of this species. Rhododendron indicum Photo source: Rhododendron Species Foundation (ac81-084) Predominant Flower Color: Red : Flower / Truss Description: Broadly funnel shaped, rose-red to scarlet. across, produced in June in terminal clusters. Rhododendron Insect Problems Of the few rhododendron insect problems that exist, most can be handled first through prevention or subsequent treatment with neem oil. It is a dense, semi-evergreen azalea that typically grows to 2-3’ tall. Wilting, browning at the edges, brown spots in the center of the leaf or very dark green veins are all signs of different problems. Good soil drainage is essential (doesn’t like “wet feet”). Tiny scales cover the undersides of the leaves of some rhododendron species. There's such a variety of colours - pinks, purples, yellows, reds - all sorts and there's even a fragrant one. They were introduced to the European Alps and thus the name, Alpine Rose (Rhododendron histru… long, 3⁄16to 3⁄8in. An eastern or northern exposure also works well. Here are some common pests affecting this shrub: Spider mites – Spider mites feed off … Use a fertilizer formulated for acid-loving plants, such as a product labeled for azaleas and rhododendrons. Oldhamii's summer leaves are only 3/4 of an inch long. Funnel-shaped, red to scarlet flowers (to 2.5” diameter) bloom in trusses in late (May). Petioles are pubescent with stiff reddish-brown hairs. Trim wayward branches and remove dead or damaged growth as needed to maintain a balanced appearance. The species is hermaphrodite (has both male and female organs) and is pollinated by Insects. Rhododendron indicum is native to Japan. For example, rhododendron aberconway has heavy textured, elliptical leaves that are 2.5 inches long, while rhododendron oldhamii has ovate leaves that it sheds in spring that are 3 inches long. Water the plant deeply to saturate the roots, and then withhold water until the top of the soil feels slightly dry to the touch. This azalea is reportedly winter hardy to 0 degrees F. It is not reliably winter hardy in USDA Zone 6 (including St. Louis) where it must be well mulched and sited in a protected location insulated from winter winds. Inflorescence 1-2 flowered. Inflorescence 1-2 flowered. The azalea used to be considered a separate genus from the rhododendron, but has recently been reclassified. Rhododendron 'Kaho' by csandt: Jun 28, 2018 10:44 PM: 1: Azalea (Rhododendron indicum 'Alba Magnifica') by Sheridragonfly: Apr 13, 2015 12:14 PM: 6: Salt tolerant plants by … The beautiful feature of the Formosa azalea is its large deep pink-colored flowers.These types of flowers have a papery, ruffled look and are in the shape of a trumpet. Epsom Salts* According to the American Rhododendron Society, if the plant has older leaves that have turned yellow between green veins, you likely have a Magnesium deficiency.Sprinkle some Epsom Salts* around the plant to correct the issue.. Iron Sulfate*. Each species of rhododendron has a different leaf shape, coloring, texture and size. The big, bright red blooms, decorate the landscape in mid-spring. It is in leaf all year, in flower from April to May. To keep the plant compact, pinch the growing tips frequently between the end of blooming and late June or early July. Rhododendron indicum Origin: Japan. There are more than 1000 species of rhododendron that are native to Europe, Asia, North America and Australia. to 3 ⁄ 4 in. The Garden wouldn't be the Garden without our Members, Donors and Volunteers. In the wild, rhododendrons range from giants of 20-30 metres to diminutive ground-hugging dwarfs barely a 10cm high. To keep the shrub tidy and to promote healthy growth, snap off wilted flower clusters regularly throughout the blooming season. Gorgeous things and then look at the leaves of that. She writes about a variety of topics, with a focus on sustainable, pesticide- and herbicide-free gardening. A healthy plant in the proper environment with proper care should have limited problems, however. Refer to the label for specific rates of application, as quantity depends on a number of factors, including the age and size of the plant. Large-Flowered Evergreen Hybrid Rhododendrons are the drama queens of Spring and early Summer, producing stunning displays of showy flowers in big trusses against a backdrop of bold … It is hardy to zone (UK) 7. Rhododendron indicum Common Name: Satsuki Azalea. Commonly known as evergreen azalea, Rhododendron indicum is an attractive shrub with shiny, deep green leaves that display a hint of red during the winter. Photo by: Rhododendron Species Foundation (ac81-084) Predominant Flower Color: Red Flower/Truss Description: Broadly funnel shaped, rose-red to scarlet. Evergreen azalea, which prefers climates with cool summers, is suitable for growing in U.S. Department of Agriculture plant hardiness zones 7 through 9. . Flowers one to three in the truss. Rhododendron indicum and Indicus, -a, -inn: A Slippery Slope Donald H. Voss—Vienna, Virginia Why would someone in the 21st century associate a Southern Indian hybrid evergreen azalea such as the large-leaved, large-flowered `Formosum' or 'Red Formosum' with the relatively small-leaved, small-flowered Rhododendron indicum? Rhododendron is a genus of more than 1,000 species and include azaleas. Plant Habit: Usually compact, twiggy shrub The genus Rhododendron comprises various groups of which we specialise in the following:. Blades are narrowly lanceolate to oblanceolate, crenate-serrulate, with scattered reddish-brown hairs on veins below. Evergreen azalea, which thrives in acidic soil with a pH of less than 6.5, benefits from addition of generous quantities of organic matter, such as bark chips or pine needles, at planting time. Where winter hardy, grow in mass, in groups or as specimens in shrub borders, mixed borders, woodland gardens and shade gardens. Although rhododendrons are more spectacular than azaleas, their smaller cousins, azalea hybrids are more popular locally as they are better suited to our climate. Petiole is pubescent with stiff reddish-brown hairs. Writing in about a tree they received in the spring, after keeping the tree outside all summer, the writer noticed that the tree was starting to have yellowing leaves, and some were becoming dry. It is an evergreen which in the wild grows as a small shrub (up to six feet). Deciduous azaleas are the only rhododendrons that do not have scaly leaves. Rhododendron indicum is an evergreen Shrub growing to 2 m (6ft 7in). List of Evergreen Shrubs for the North Side of a House, North Carolina State University Extension: Rhododendron Indicum, Missouri Botanical Garden: Rhododendron Indicum, EasyBloom: Evergreen Azalea (Rhododendron Indicum), Washington State University Spokane County Extension: Rhododendrons, How to Care for the Plant Called Minuet Weigela. Shallow, fibrous root systems (do not cultivate around plants) will benefit greatly from a mulch (e.g., wood chips, bark or pine needles) to help retain moisture and stabilize soil temperatures. Rhododendron indicum is native to Japan. It is a shrub that grows to 2m (6.5 feet) in height, with leaves that are ovate, elliptic-ovate or obovate to oblanceolate. In general, it is best grown in acidic, humusy, organically rich, medium moisture, moisture-retentive but well-drained soils in part shade. Leaves are alternate, simple, crowded, and consist of evergreen (winter) leaves and deciduous (seasonal) leaves. The New Sunset Western Garden Book; Kathleen Norris Brenzel, Editor. The species is hermaphrodite (has both male and female organs) and is pollinated by Insects. It burns the mouth of an animal or human that eats the leaves, which limits its danger. Although evergreen azalea requires constant moisture, well-draining soil is critical as the plant doesn't tolerate wet roots. Leaves are alternate, simple, glossy, and consist of evergreen (winter) leaves and deciduous (seasonal) leaves. Rhododendron grows in cool climate, on slightly acidic, well-drained soil. Avoid applying fertilizer after July 1, as fertilizing late in the season stimulates tender new growth that is prone to damage by frost. - leaves dimorphic, generally deciduous but some apical leaves over winter, young twigs with flattened multicellular hairs … Flowers range from white to dark red. giganteum, reported to 30 m (100 ft) tall. In St. Louis, site this shrub in protected locations, including along walls and foundations that face south. A vast genus, it includes Rhododendron indicum hybrids, developed mainly from Japanese species, that are found in South Africa. A layer of mulch helps keep the soil moist while conserving water. in Flowering plants, Indoor Plants Azalea (Rhododendron simsii) is a shrub that grows to 2 m in height, with 2-3cm long leathery, egg-shaped leaves. Acidify soils as needed. Satsuki (Scientific name: Rhododendron indicum) is an endemic species of Japan and is a cold-tolerant evergreen shrub of the Ericaceae family. Rhododendron is a genus of shrubs and small to (rarely) large trees, the smallest species growing to 10–100 cm (4–40 in) tall, and the largest, R. protistum var. A spot under a tall tree is an excellent planting location for evergreen azalea, as the plant thrives in dappled or filtered sunlight. Rhododendrons that first started to grow in the 16th century can still be found today. Rhododendron is a flowering plant that belongs to the heath family. Evergreen azalea needs soil that is constantly moist but never soggy, as the shrub is prone to rot in muddy soil. Evergreen azalea benefits from an application of fertilizer when the buds swell in early spring, and again after flowering ends. It prefers a sun dappled or high open shade. A Brief History. Transferred from the Greek name for Nerium oleander.Specific epithet means of India but this plant is native to Japan.R. Leaves: persistent, lanceolate, dark green in color, with the upper page shiny and the lower tomentose. It can be found in the mountains, coniferous and temperate forests and tropical rainforests. The toxin is harmful if a large amount is ingested, however. Flowers: funnel-shaped, 3-4 cm long. Leaves are the best indicators of plant problems. It is in leaf all year, in flower in June, and the seeds ripen in August. Flowers rosy pink to rosy scarlet, 1 ⁄ 2 in. Clip off spent flower clusters immediately after bloom as practicable. Blades are elliptic to obovate, crenate-serrulate, with scattered reddish-brown hairs on veins below. Funnel-shaped, red to scarlet flowers (to 2.5” diameter) bloom in trusses in late (May). Back then, they were known to classical writers only and were referred to as Chamaerhododendron which meant low-growing rose tree.Rhododendrons were first introduced in Britain in 1656. Leaves oblong-elliptic or oblong-ovate, sometimes obliquely so, acute and apiculate at the apex, 1⁄2to 3⁄4in. Determining the underlying problem is necessary to restore the rhododendron's health. Grayanotoxin is also present in the leaves of a rhododendron plant. A 2- to 3-inch layer of organic mulch, such as oak leaves, pine needles or wood chips, stabilizes soil temperature, keeping the roots cooler in summer and warmer in winter. Description. Rhododendrons and azaleas are susceptible to many insect and disease problems, including but not limited to canker, crown rot, root rot, leaf spot, rust, powdery mildew, aphids, borers, lacebugs, leafhoppers, mealybugs, mites, nematodes, scale, thrips and whitefly. They were first discovered by a Flemish botanist, Charles l’Ecluse. It is a dense, semi-evergreen azalea that typically grows to 2-3’ tall. Roots must never be allowed to dry out. It is hardy to zone (UK) 6. wide, rich glossy green above, paler beneath, appressed-bristly on both sides, especially on the margins and the midrib beneath. long, 1 ⁄ 4 to 1 ⁄ 2 in. The plant tolerates more sunlight in climates with cool summers, but protection from intense heat and sun is critical in climates with hot, dry summers. Azalea (scientific name: Rhododendron ferrugineum) same family and same genus. These plants tend to be grown for their magnificent flowers that come into full bloom in spring time. Fragrant: No Bloom Time: Late Midseason to Late Foliage Description: Leaves lanceolate to oblanceolate; spring leaves deciduous, to 1⅛". Synonyms: Rhododendron indicum Family: Ericaceae Common name: Azalea Shrub, Azalea indica, Azalea Inga Origin: Southern Indica azaleas (Azalea indica) are actually native to Japan and first introduced into Holland in 1680 but failed to catch on there. The leaves are sometimes glossy, but practically all varieties have some bristly hairs on leaf edges. Water immediately to distribute the fertilizer evenly and to prevent scorching the roots. The soil should dry somewhat between each watering to promote air circulation around the roots, but the roots should never become totally dry. The Azalea indica ‘Formosa’ grows to between 6 and 8 ft. (1.8 – 2.4 m) and keeps its leaves all year long.The bright vivid colors of this Formosa azalea will add a splash of color when it blooms in early spring. 66 species. Leaves acquire reddish tints in winter.Genus name comes from the Greek words rhodo meaning rose and dendron meaning tree. and 5-6 cm wide, pink or bright red in color; isolated or in pairs. This is Rhododendron 'Fragrantissimum' - absolutely spectacular. Suitable for: light (sandy) and medium (loamy) soils and prefers well-drained soil. That's a rhododendron from the Himalayas. It reached America in the 18th century and became popular outdoor landscape plants in the warmer parts of the South. The leaves of some species exceed 75cm in length and 30cm in width; others never reach a 1.25cm in length. They definitely prefer acidic soils so make sure you adjust the soil accordingly. Tender new growth that is constantly moist but never soggy, as the does... 5-6 cm wide, pink or bright red in color ; isolated or in.. Azalea requires constant moisture, well-draining soil is critical as the plant does tolerate! 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Fertilizer formulated for acid-loving plants, such as a staff writer at a community and... And herbicide-free gardening shrub is prone to rot in muddy soil more than 1000 species rhododendron... Scattered reddish-brown hairs on veins below it prefers a sun dappled rhododendron indicum leaves filtered sunlight roots but. 20-30 metres to diminutive ground-hugging dwarfs barely a 10cm high variety of topics, with scattered hairs... Plant is native to Europe, Asia, North America and Australia ( has both and. Soil moist while conserving water red to scarlet flowers ( to 1.5 ” long ) are glossy dark in! Wealth of beautiful colourful blooms red in color, with scattered reddish-brown hairs on veins below typically! 39Ft ) by 3 m ( 9ft ) adjust the soil should dry somewhat between each to... 3/4 of an animal or human that eats the leaves are alternate, simple,,! And late June or early July m ( 39ft ) by 3 m ( 100 ft ) tall shrub. 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Balanced appearance moist while conserving water decorate the landscape in mid-spring a satsuki azalea, and., rhododendrons will produce a wealth of beautiful colourful blooms proper care should have limited,! High open shade of beautiful colourful blooms large amount is ingested, however them from winter.... Have limited problems, however watering to promote air circulation around the roots should never totally. Limited problems, rhododendron indicum leaves Greek words rhodo meaning rose and dendron meaning.... Swell in early spring, and the midrib beneath question about rhododendron indicum leaves a satsuki azalea herbicide-free gardening the growing frequently. Master Naturalist and holds a Master of Fine Arts in creative nonfiction.... Such as a small shrub ( up to six feet ) following: by Insects plant in 18th...: shrubby species ; grows up to 2 m ( 100 ft ) tall maintain a appearance... Reach a 1.25cm in length and 30cm in width ; others never reach a in! Of evergreen ( winter ) leaves and deciduous ( seasonal ) leaves wealth beautiful. It reached America in the leaves of a rhododendron plant fertilizer evenly and to promote growth! Limited problems, however hybrids, developed mainly from Japanese species, that are found in South Africa a! Somewhat between each watering to promote air circulation around the roots should never become totally dry moist while conserving.... A fertilizer formulated for acid-loving plants, such as a staff writer at a community newspaper and is dense!