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Green 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. Green ash, a native woodland tree found throughout the Midwest, had been used extensively as a shade and street tree. 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.

To find suitable replacements for this tree, go The Morton Arboretum’s tree and plant finder.  Before purchasing or planting, be sure to check for any local or state guidelines on any selected species, and ensure that this plant is suitable for its habitat by checking its attributes at mortonarb.org or plants.usda.gov.

  • 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 50-60 feet
  • Mature width 25-40 feet
  • Light exposure Full sun (6 hrs direct light daily), Partial sun / shade (4-6 hrs light daily)
  • Hardiness zones Zone 2, Zone 3, Zone 4, Zone 5 (Northern Illinois), Zone 6 (City of Chicago), Zone 7, Zone 8, Zone 9
  • Soil preference Moist, well-drained soil, Wet soil
  • Tolerances Alkaline soil, clay soil, Dry sites, Occasional drought, Occasional flooding, Road salt, Wet sites
  • Season of interest early fall, mid fall
  • Flower color and fragrance Inconspicuous
  • Shape or form Oval, Round, Upright
  • Growth rate Fast
  • Transplants well Yes
  • Planting considerations Aggressive, Weak wood and branch structure
  • Wildlife Game birds, Insect pollinators, Migrant birds
  • Has cultivars Yes

Highly susceptible to the following diseases and pests:

Emerald ash borer

Size:

Green ash grows 50 to 60 feet tall and 25 to 40 feet wide.

Native geographic location and habitat:

It is commonly found in wet, lowland sites. C-Value: 1

Bark color and texture:

The bark is light gray and loosely ridged and furrowed.

Leaf description:

Dark green compound leaves are in pairs (opposite), with five to nine leaflets on each leaf. The leaves change to yellow or yellow-green in fall.

Flower arrangement, shape, and size:

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

Fruit, cone, nut and seed descriptions:

Fruit are winged seeds borne in clusters.

Plant care:

This tree is tolerant of wet sites, dry sites, alkaline soils, poor soils, and wind.

List of pests and diseases:

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

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