Showy Mountain Ash

Showy Mountain Ash Sorbus DecoraShowy mountain ash (Sorbus decora) also known as northern mountain ash is a native of Iowa. It is a large shrub or small tree similar to the American mountain ash, but different because the leaflets are narrow, oblong-oval, only 2 to 3 times as long as broad with a pointed tip, and paler (whiter) beneath.

showy mountain ash tree covered in red berries
Showy Mountain Ash Tree - Photo by Bill Cook, Michigan State University,

Habitat: Found only in extreme northeast Iowa, requires well drained fertile soil.

Hardiness: Zones 3 through 9

Growth Rate: Moderate to Fast

Mature Shape: Slightly pyramidal, upright with a rounded crown

Height: 50- 80 feet

Width: 50-70 feet

Site Requirements: Native to Iowa, ash trees grow best in full sun and moist, well-drained soils. Ash trees are tolerant of a wide range of soil conditions.

Leaves: Opposite-branching and pinnately compound

Flowering Dates: May - July

Seed Dispersal Dates: August - June

Seed Bearing Frequency: Yearly

Seed Stratification: Prechill for 2 months at 34°F to 40°F

The flowers are larger than American mountain ash; 3/8 inch across, and the cluster is more diffuse. The fruits are also larger at 3/8 inch across. 

Its range is from southern Greenland, Labrador, and Newfoundland westward to northern Ontario and Minnesota; and southward to Maine, New York, Ohio, northern Indiana, and extreme northeast Iowa. It can be found naturally occurring in woodlands and on rocky shores and slopes preferring well drained rich soil.

white showy mountain ash flowers
Showy Mountain Ash Flowers - Photo by Bill Cook, Michigan State University, 

Diseases that Can Affect Showy Mountain Ash

Insects that Can Affect Showy Mountain Ash

yellow autumn showy mountain ash leaves
Showy Mountain Ash Leaves - Photo by Bill Cook, Michigan State University,

red showy mountain ash berries
Showy Mountain Ash Fruit - Photo by Bill Cook, Michigan State University,