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Korean Mountain Ash

Sorbus alnifolia (SOR-bus al-nih-FOH-lee-ah)

Family: Rosaceae Non-native Canopy (>40 ft)

Sorbus alnifolia , or Mountain Ash, is a moderate to fast growing flowering tree that begins as pyramid-shaped but matures to a more rounded appearance. It grows best in moist, acidic, well-drained soils in full sun. A native of Asia, this tree prefers cool climates and will not grow well in the hot and humid summer conditions south of USDA Zone 7. It generally requires little pruning, but if you are driven to prune, apply your skills from late fall to early spring. It is less susceptible to pest and disease than other Sorbus spp., but is not a good street tree and is not tolerant of air pollution. The plant tolerates strong winds but not maritime exposure It is, however, easy to transplant. Mountain Ash, is noted for its attractive form, creamy white flowers, simple beach-like leaves, red fall fruit and good fall color. Golden orange fall color can be outstanding. Insects, Diseases, and Other Plant Problems: Mountain Ash is noted for its resistance to borers that attack other species of mountain ash. It is considered to be one of the best of the mountain ashes because of its pest resistance and form. However, bacterial fireblight can be a severe problem, causing scorched leaves at the branch ends. Scab can cause significant defoliation. Cankers, crown gall, powdery mildew and rust may also occur. Insect visitors include aphids, sawfly and scale. Stressed trees are generally more susceptible to attack from canker and borers.

Source: NC State Extension Gardener Plant Toolbox ↗ NC State Extension Gardener Plant Toolbox, 58 attributes.

How it fits the guild

Guild layer 1 - Canopy (>40 ft) Optimal soil pH Acid (<6.0)
See companions & conflicts ↓

Companions & Conflicts

Curated pairwise relationships between this plant and others in the library — who feeds whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.

No curated interactions recorded for this species yet.

Also noted by NC State

Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.

Full plant profile

Growing Conditions
Plant type
Tree
Life cycle
Woody
USDA zones
3a, 3b, 4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b
Light
Full sun (6 or more hours of direct sunlight a day)
Soil texture
Clay; Loam (Silt); Sand
Soil pH
Acid (<6.0)
Soil drainage
Good Drainage | Moist
NC region
Coastal; Mountains; Piedmont
Mature size
Height: 30 ft. 0 in. - 50 ft. 0 in. | Width: 20 ft. 0 in. - 30 ft. 0 in.
Growth rate
Rapid
Maintenance
Medium
Canopy layer
1 - Canopy (>40 ft)
Form & Appearance
Habit / form
Pyramidal; Rounded
Texture
Medium
Foliage
Deciduous
Leaf color
Green
Leaf type
Simple
Leaf arrangement
Alternate
Leaf shape
Lanceolate; Ovate
Leaf margin
Dentate
Leaf feel
Glossy
Leaf value
Showy
Leaf size
3-6 inches long
Hairs present
Yes
Leaf detail
Dark green 2 to 4 inch leaves that turn orange, golden brown in the fall. Leaves are simple (leaves of most other species of mountain ash are compound).
Fall color
Brown/Copper; Orange
Flower color
White
Flower value
Showy
Flower form
Corymb
Flower size
1-3 inches
Flower detail
Dense flattened corymbs (to 3 inches across) of 6 to 10 small 5-petaled white flowers appear in May.
Bloom time
Summer
Fruit color
Orange; Red/Burgundy
Fruit type
Berry; Pome
Fruit value
Showy
Fruit size
< 1 inch long
Fruit detail
Flowers are followed by pink to orange to scarlet berry-like pomes (to 5/8 inch long) that ripen in fall and remain on the tree even after leaf-drop.
Bark color
Light Gray
Bark detail
The smooth, gray, beech-like bark is quite noticeable in winter.
Wildlife & Ecology
Native status
Non-native
Origin
Temperate Asia
Wildlife value
Attracts birds.
Attracts
Songbirds
Food & Medicine
Harvest time
Fall
Fruit type
Berry; Pome
Landscape Use
Landscape theme
Winter Garden
Design feature
Flowering Tree
Garden tags
#deciduous #winter interest #wind tolerant #flowering tree #shade tree #wet soils tolerant
Problems & Resistance
Resistant to
Wet Soil; Wind
Propagation
Seed

Planted at Hunnicutt

Nobody’s planted this one yet.