Green Ash

Green Ash Fraxinus pennsylvanicaGreen ash (Fraxinus pennsylvanica) is one of our most adaptable native trees. Green ash is characterized by having opposite, pinnately compound leaves with 5 to 9 leaflets (usually 7). The leaves are 10 to 12 inches in length with individual leaflets 2 to 6 inches long. The leaflets are long-pointed at the tip with a tapering base. The leaflet stalks are 1/16 to 3/16 inches in length, often with a slight winged appearance. The leaflets are dark green and glossy on the upper surface, while lighter green below. The margins are usually conspicuously toothed.

green ash tree
Green Ash Tree - Photo by Paul Wray, Iowa State University

Habitat: Grows on the edges of moist woods. Found throughout the state.

Hardiness: Zones 3 though 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.

Flowering Dates: March - May

Seed Dispersal Dates: October - Spring

Seed Bearing Age: 10 years

Seed Bearing Frequency: Yearly

Seed Stratification: Warm stratification for 2 months at 68°F followed by pre-chilling for 2-5 months at 34°F to 40°F.

Branches are stout, round, green and smooth to hairy when young, becoming smooth and turning ash-gray with age with half circular leaf scars. The fruit is a paddle-shaped samara which often persists into winter. The bark is ashy-gray or gray-brown, furrowed, with narrow interconnecting ridges enclosing diamond-shaped spaces.

Green ash is the most widely distributed ash in the United States. It is native to all of Iowa. It is found most often growing on bottomlands or on wet upland sites. Its common associates include cottonwood, silver maple, willows, hackberry, and black walnut. It does however, grow remarkable well on a wide variety of sites and if often found as a common tree of wood edges on upland sites.

Like white ash, its wood is hard, tough, and relatively straight grained and used for a variety of products from tool handles to furniture to pallets. 

Green ash is the fastest growing of the ashes, attaining heights of 50 to 70 feet. It has been used extensively for a shade tree because of its adaptability and relatively fast growth rate. Most shade tree selections are male to avoid seed production. It turns a golden yellow in the fall.

Diseases that Can Affect Green Ash

Insects that Can Affect Green Ash

three variations of green ash twigs ranging from dark brown to light ash gray
Green Ash Twigs - Photos by Paul Wray, Iowa State University

green ash narrow leaf-like fruit
Green Ash Fruit - Photo by Paul Wray, Iowa State University

green and purple green ash flowers
Green Ash Flowers - Photo by Paul Wray, Iowa State University

green ash leaves on twigs
Green Ash Leaves - Paul Wray, Iowa State University