Content Detail

Black ash is very susceptible to the emerald ash borer (Agrilus planipennis) and is not recommended for planting anywhere in this region. It usually requires removal or regular insecticide treatments. Black ash is a native woodland tree found throughout the Midwest. This species is native to the Chicago region according to Swink and Wilhelm’s Plants of the Chicago Region, with updates made according to current research. Learn more at the Emerald Ash Borer Information Network’s website.

To find suitable replacements for this tree, go to The Morton Arboretum’s tree and plant finder.  Before purchasing or planting, be sure to check for any local or state guidelines, and ensure that this plant is suitable for its habitat by reviewing planting considerations or by finding it in the USDA Plants Database.

  • Family (English) Olive
  • Family (botanic) Oleaceae
  • Tree or plant type Tree
  • Foliage Deciduous (seasonally loses leaves)
  • Native locale Chicago area, Illinois, North America
  • Size range Large tree (more than 40 feet)
  • Mature height 40-50 feet
  • Mature width 20-35 feet
  • Light exposure Full sun (6 hrs direct light daily)
  • Hardiness zones Zone 2, Zone 3, Zone 4, Zone 5 (Northern Illinois)
  • Soil preference Acid soil, Wet soil
  • Tolerances Alkaline soil, clay soil, Occasional flooding, Wet sites
  • Season of interest early fall
  • Flower color and fragrance Inconspicuous
  • Shape or form Narrow, Open
  • Growth rate Slow
  • Transplants well Yes
  • Planting considerations Highly susceptible to ice damage
  • Wildlife Browsers, Game birds, Insect pollinators, Migrant birds, Songbirds
  • Has cultivars Yes

More Information

Size and Method of Spreading

Black ash is a medium to large tree, growing 40 to 50 feet tall and 20 to 35 feet wide.

Native Geographic Location and Habitat

C-Value: 10. Black ash is commonly found in wet, lowland sites.

Bark Color and Texture

The bark is light gray and loosely ridged and furrowed.

Leaf Description

Compound leaves are in pairs (opposite), with 7 to 11 leaflets on each leaf. The leaves are dark green in summer, changing to purplish in fall.

Flower Description

Male and female flowers are on separate trees (dioecious). They are not ornamentally important. The flowers appear in spring.

Fruit Description

The fruit is formed on female trees only. They are winged seeds.

Care Knowledge

Plant Care

This tree is tolerant of wet sites. It prefers a slightly acidic soil.

Pests, Diseases, and Tolerances

Susceptibility to the emerald ash borer makes this tree unsuitable for the landscape.


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