Introduction
Common Ash is a broad, spreading, deciduous tree, capable of reaching 100 feet or more in height but most often seen growing at a moderate pace at 70 to 80 feet with a 60 to 90-foot spread. The dark green, multi-divided leaves are 10 to 12 inches long and usually drop off in autumn while still green but some cultivars may turn an attractive yellow first. The inconspicuous springtime flowers are followed by clusters of 1.5-inch-long, winged fruits which turn brown and remain on the trees well after the leaves have fallen. The low-branched, rounded silhouette of naked branches on top of the short trunk and the black, dormant leaf buds help to make common Ash an attractive winter landscape element.
Credit: Ed Gilman
General Information
Scientific name: Fraxinus excelsior
Pronunciation: FRACK-sih-nus eck-SELL-see-or
Common name(s): Common Ash, European Ash
Family: Oleaceae
USDA hardiness zones: 5A through 8A (Fig. 2)
Origin: not native to North America
Invasive potential: little invasive potential
Uses: shade; highway median
Availability: somewhat available, may have to go out of the region to find the tree
Description
Height: 60 to 80 feet
Spread: 60 to 90 feet
Crown uniformity: symmetrical
Crown shape: round
Crown density: dense
Growth rate: fast
Texture: medium
Foliage
Leaf arrangement: opposite/subopposite (Fig. 3)
Leaf type: odd-pinnately compound
Leaf margin: serrate
Leaf shape: ovate, lanceolate
Leaf venation: pinnate
Leaf type and persistence: deciduous
Leaf blade length: 2 to 4 inches
Leaf color: green
Fall color: yellow
Fall characteristic: showy
Flower
Flower color: green
Flower characteristics: not showy
Fruit
Fruit shape: elongated
Fruit length: 1 to 3 inches
Fruit covering: dry or hard
Fruit color: tan, green
Fruit characteristics: attracts birds; showy; fruit/leaves a litter problem
Trunk and Branches
Trunk/bark/branches: branches droop; not showy; typically one trunk; thorns
Pruning requirement: needed for strong structure
Breakage: resistant
Current year twig color: brown, gray
Current year twig thickness: thick
Wood specific gravity: unknown
Culture
Light requirement: full sun
Soil tolerances: clay; sand; loam; alkaline; acidic; well-drained
Drought tolerance: high
Aerosol salt tolerance: high
Other
Roots: not a problem
Winter interest: no
Outstanding tree: no
Ozone sensitivity: tolerant
Verticillium wilt susceptibility: susceptible
Pest resistance: sensitive to pests/diseases
Use and Management
Like many Ashes, the tree requires careful training and pruning to develop a central leader with strong branch structure. Without pruning many branches originate at the same position on the trunk which makes them prone to breakage and shortens their life. Select, then develop up to a dozen main branches well-spaced along the trunk as far up the tree as practical.
Common Ash should be grown in full sun or partial shade and prefers moist, rich soil, and grows well on calcareous soil. Grows best on deep soils with adequate moisture, although drought tolerance is moderate. It tolerates poorly-drained, low-quality and alkaline soil. Its use is probably limited by borers which often infest the trunk and cause the tree to decline. Probably best suited for landscapes with plenty of soil space for root expansion, not in confined urban soil.
The cultivars are probably more available than the species. A few of the many cultivars include: `Aurea' - slow-growing, perhaps to 50 feet tall and wide, deep yellow fall color, yellow twigs; `Aurea Pendula', with yellow, pendulous branchlets; `Aureovariegata', leaves variegated or edged with yellow; `Hessei', 60 feet tall, single leaves, very disease-resistant, seedless, yellow or little fall color; `Nana', compact, slow-growing dwarf form with small leaflets; `Spectabilis', pyramidal shape; `Pendula', weeping form; and `Rancho' (also known as `Kimberly'), 30 feet tall, round canopy, yellow fall foliage.
Propagation of the species is by seed.
Pests
Borers can kill trees. The most common borers infesting Ash are Ash borer, lilac borer and carpenterworm. Ash borer bores into the trunk at or near the soil line causing tree dieback. Lilac borer causes swellings on the trunk and limbs where the insect enters the tree. The carpenterworm larvae bore into the heartwood but come to the outside of the tree to push out frass and sawdust. Heavily infested trees can be severely weakened. Keep trees as healthy as possible by fertilizing regularly and watering during dry weather, particularly newly transplanted trees or those stressed from some other problem.
Aphids are often seen but are usually not serious.
In late summer, fall webworm could cover branches with webbing. The nests in branches close to the ground can be pruned out when first noticed.
Diseases
There may be a variety of diseases which infect this Ash. It has not been grown or used extensively.
