Rhododendron yedoense f. poukhanense
Common Name(s):
- Phonetic Spelling
- rho-doh-DEN-dron yeh-DOH-en-see forma pook-HAH-nen-see
- This plant has high severity poison characteristics.
- See below
- Description
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Korean azalea is a woody, deciduous to semi-evergreen shrub in the Ericaceae (blueberry) family and native to central and southern Korea. This spreading shrub reaches a height of 3 to 6 feet and a width of 6 to 12 feet, maintaining its leaves in mild winters. It is the parent plant to many of the current hybrid evergreen azaleas. The genus name derives from the Greek words rhodo, which means rose, and dendron, meaning tree. Yedo, from the specific epithet yedoense, was the former city name of Tokyo, Japan.
Plant it in partial to full shade in moist, rich, well-drained soils. Good drainage is essential as wet feet can cause disease problems and root rot; however, the soil should not be allowed to dry out completely. A thick layer of organic mulch will help keep the soil moist and the temperature even for the best root growth. It will need protection from drying winter winds.
It looks attractive planted in small groups in shrub borders, as an informal hedge, or planted along a foundation. Its showy fragrant flowers make it an excellent choice for specimen planting near a patio or walkway or in a pollinator or butterfly garden where the showy, pink- purple blooms will provide nectar for visiting butterflies and hummingbirds.
Insects, Diseases, and Other Plant Problems: Insect problems include aphids, borers, lace bugs, leafhoppers, mealybugs, mites, nematodes, scale, thrips, and whitefly. Diseases include canker, crown rot, root rot, leaf spot, rust, and powdery mildew, though Korean azalea has shown better resistance to Phytophthora root rot. This plant is frequently damaged by deer but tolerates browsing by rabbits.
While these shrubs remain very popular for landscape use, many cultivars are susceptible to Phytophthora root rot—this leads to leaf loss, reduced vigor, branch dieback, and wilting. Implement good cultural practices first, such as improving drainage with organic matter or berms and avoiding overwatering or overfertilization. However, if you have a site with a history of this disease, consider planting one of the root rot-resistant alternative species listed in the left-hand sidebar.
For suitable alternatives, see this video created by Charlotte Glen as part of the Plants, Pests, and Pathogens series.
VIDEO Created by Elizabeth Meyer for "Trees, Shrubs and Conifers" a plant identification course offered in partnership with Longwood Gardens.
- Profile Video:
- See this plant in the following landscape:
- Cultivars / Varieties:
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- Tags:
- Cultivars / Varieties:
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- Tags:
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Attributes:
- Genus:
- Rhododendron
- Species:
- yedoense
- Family:
- Ericaceae
- Life Cycle:
- Woody
- Country Or Region Of Origin:
- Korea
- Wildlife Value:
- Flowers attract butterflies and hummingbirds. Members of the genus Rhododendron support the following specialized bee: Andrena (Andrena) cornelli.
- Particularly Resistant To (Insects/Diseases/Other Problems):
- Phytophthora root rot
- Dimensions:
- Height: 3 ft. 0 in. - 6 ft. 0 in.
- Width: 6 ft. 0 in. - 12 ft. 0 in.
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Whole Plant Traits:
- Plant Type:
- Poisonous
- Shrub
- Woody Plant Leaf Characteristics:
- Deciduous
- Semi-evergreen
- Habit/Form:
- Spreading
- Maintenance:
- Medium
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Cultural Conditions:
- Light:
- Dappled Sunlight (Shade through upper canopy all day)
- Deep shade (Less than 2 hours to no direct sunlight)
- Partial Shade (Direct sunlight only part of the day, 2-6 hours)
- Soil Texture:
- High Organic Matter
- Loam (Silt)
- Sand
- Soil pH:
- Acid (<6.0)
- Soil Drainage:
- Good Drainage
- Moist
- Available Space To Plant:
- 12 inches-3 feet
- 6-feet-12 feet
- NC Region:
- Coastal
- Mountains
- Piedmont
- USDA Plant Hardiness Zone:
- 4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b, 9a, 9b
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Fruit:
- Fruit Type:
- Capsule
- Fruit Description:
- Dry capsule
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Flowers:
- Flower Color:
- Pink
- Purple/Lavender
- Flower Inflorescence:
- Raceme
- Flower Value To Gardener:
- Fragrant
- Showy
- Flower Bloom Time:
- Spring
- Flower Shape:
- Funnel
- Flower Petals:
- 4-5 petals/rays
- Flower Size:
- 1-3 inches
- Flower Description:
- Showy slighly fragrant 2 inch pink purple flowers with a dark blotch on each of 5 petals. Flowers appear in clusters of 2-4 from April-May
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Leaves:
- Woody Plant Leaf Characteristics:
- Deciduous
- Semi-evergreen
- Leaf Color:
- Green
- Deciduous Leaf Fall Color:
- Orange
- Red/Burgundy
- Leaf Type:
- Simple
- Leaf Arrangement:
- Alternate
- Leaf Margin:
- Entire
- Hairs Present:
- No
- Leaf Description:
- Dark green simple alternate leaves with entire margins. Attractive red-orange fall color.
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Stem:
- Stem Is Aromatic:
- No
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Landscape:
- Landscape Location:
- Patio
- Walkways
- Woodland
- Landscape Theme:
- Butterfly Garden
- Pollinator Garden
- Design Feature:
- Foundation Planting
- Hedge
- Mass Planting
- Small groups
- Specimen
- Attracts:
- Butterflies
- Hummingbirds
- Specialized Bees
- Resistance To Challenges:
- Diseases
- Rabbits
- Problems:
- Poisonous to Humans
- Problem for Cats
- Problem for Dogs
- Problem for Horses
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Poisonous to Humans:
- Poison Severity:
- High
- Poison Symptoms:
- Salivation, watering of eyes and nose, abdominal pain, loss of energy, depression, nausea and vomiting, diarrhea, weakness, difficult breathing, progressive paralysis of arms and legs, coma
- Poison Toxic Principle:
- Grayanotoxins, Andromedotoxin
- Causes Contact Dermatitis:
- No
- Poison Part:
- Bark
- Flowers
- Fruits
- Leaves
- Roots
- Sap/Juice
- Seeds
- Stems