Fraxinus quadrangulata

Common Names

Blue Ash

Summary

Blue ash is a central U.S. native broadleaf deciduous tree with four-ridged square twigs and opposite, pinnately compound leaves of 5–11 leaflets; it typically reaches about 50–70 ft in height with a broad, rounded crown. Distinctive features include four-sided twigs, light gray bark, and foliage that is deep green in summer and turns yellow in autumn; flowers are small and purple, and fruit consists of winged samaras 2.5–5 cm long.

Hardiness zones 4–7; prefers full sun and well-drained soils, tolerating dry to moist conditions and drought, with a medium growth rate and low maintenance. Native to the Midwest U.S. and parts of Ontario, it serves as a shade tree in lawns and streets; wood is strong and heavy for flooring, interior finishes, and tool handles, while inner bark historically yielded blue dye and sap turns blue on exposure to air. Emerald ash borer poses a serious threat to this species.

Lifecycle

Perennial

Height

50-70 feet

Spread

50-60 feet

Hardiness Zones

Zones 4-7

Sunlight Requirements

Ideally full sun; tolerates partial sun to partial shade.

Soil Type

Moist, well-drained loam soil; pH 6.0–8.0.

Soil Drainage

Well-drained soils

Soil pH

6.0–8.2

Bloom Color

Purplish

Bloom Time

Spring

Foliage Color

Dark green foliage, may turn yellow in fall.

Fall Foliage Color

Yellow

Leaf Lifecycle

Deciduous

Growth Rate

12-18 inches per year, fast-growing, with vigorous growth in full sun and slower growth in shade

Seasons of Interest

Spring and Fall

Propagation Methods

Seeds, Cuttings, Layering

Attracts Wildlife

Bees, butterflies, other pollinators, birds