What hardiness zones is Fraxinus latifolia suitable for?

Fraxinus latifolia is suitable for USDA hardiness zones 6, 7, 8, 9.

What are the sun requirements for Fraxinus latifolia?

Fraxinus latifolia requires Full Sun.

How much water does Fraxinus latifolia need?

Fraxinus latifolia has High water needs.

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Broadleaf Deciduous Trees

Fraxinus latifolia

Oregon ash

OleaceaeNorth America

At a Glance

TypeTree

HabitUpright

FoliageDeciduous

Height40–80 feet (12–24 m)

Width20–40 feet (6–12 m)

Maturity25 years

Growing Zones

USDA Hardiness Zones

6 - 9

Zone 6

Zone 7

Zone 8

Zone 9

These zones indicate the coldest temperatures this plant can typically survive.

Frost Tolerancehardy

Key Features

Deer Resistant

Native to North America

Maintenancelow

Overview

Fraxinus latifolia, commonly called Oregon ash, is a large deciduous tree in the family Oleaceae and the only ash species native to the Pacific Northwest and the western United States. It is native to riparian corridors, floodplains, and moist lowland forests from southwestern British Columbia south through western Washington and Oregon to central California, typically growing at elevations below 3,000 feet (900 m) alongside Red alder, Black cottonwood, and Oregon white oak. Oregon ash grows 40–80 feet (12–24 m) tall with a straight trunk, an oval to rounded crown, and distinctive gray bark developing a regular diamond-furrowed pattern on mature specimens. The opposite, pinnately compound leaves carry 5–7 broadly elliptic, dark green leaflets 2–5 inches (5–12 cm) long, creating a fine-textured, light-filtering canopy. Flowers are inconspicuous, dioecious (male and female trees separate), and appear before the leaves in early spring; female trees produce clusters of winged samaras (keys) that persist into winter and provide food for birds. Fall color is a consistent, clear yellow. A significant ecological tree — among the most important riparian trees in the Pacific Northwest — providing critical habitat for neotropical migrant birds and supporting numerous invertebrate species.

Native Range

Native to riparian corridors, floodplains, moist bottomland forests, and the edges of wetlands from southwestern British Columbia (Fraser River valley and Vancouver Island) south through western Washington and Oregon to central California (Fresno County), at elevations from sea level to approximately 3,000 feet (900 m). Grows in moist to seasonally flooded, often poorly drained soils. Native to North America.

Suggested Uses

Oregon ash is the premier large native riparian tree for Pacific Northwest lowland landscapes, wetland restorations, and rain garden projects. Exceptional for streambank stabilization, floodplain restoration, and ecological plantings in moist to seasonally wet sites. Outstanding combined with Red alder, Black cottonwood, Pacific willow, Cornus sericea, and Oemleria cerasiformis in native riparian plantings. Of considerable educational significance as the only western North American ash and an important component of PNW lowland ecology. Suitable for large-scale landscape and municipal planting where space and moisture are available. Allow 30–40 feet (9–12 m) clearance from structures.

How to Identify

Oregon ash is identified by its opposite, pinnately compound leaves with 5–7 broadly elliptic, dark green leaflets 2–5 inches (5–12 cm) long with slightly toothed or entire margins, on a large deciduous tree with gray, diamond-furrowed bark on mature specimens. The leaflets are broader and less toothed than most other ash species, with a distinctive velvety pubescence on the underside of young leaves and rachis. In spring, inconspicuous flowers appear before the leaves. Female trees produce abundant winged samaras in pendant clusters that persist through winter. The opposite compound leaves combined with gray diamond-furrowed bark on a riparian or bottomland site is diagnostic in the Pacific Northwest.

Appearance

Size & Dimensions

Height40' - 80'

Width/Spread20' - 40'

Reaches mature size in approximately 25 years

Colors

Flower Colors

green

Foliage Colors

green

Fall Foliage Colors

yellow

Bloom Information

Bloom Period

~3 weeks

Spring

Oregon ash produces inconspicuous, wind-pollinated flowers in early spring (March–April) before the leaves emerge. Male and female flowers are borne on separate trees (dioecious); male flowers appear in small dense clusters, female flowers in open panicles. The flowers have no ornamental value. Female trees produce clusters of winged samaras (keys) 1–2 inches (2.5–5 cm) long that develop through summer and persist into winter, providing food for finches, grosbeaks, and other seed-eating birds.

Detailed Descriptions

Flower Description

Inconspicuous, wind-pollinated; no ornamental value; female trees produce clusters of winged samaras (keys) 1–2 inches (2.5–5 cm) persisting through winter

Foliage Description

Opposite, pinnately compound; 5–7 broadly elliptic, dark green leaflets 2–5 inches (5–12 cm), slightly toothed or entire; velvety underside on young leaves

Growing Conditions

Sun Requirements

Full Sun

Partial Shade

Requires 4-12 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.5 - 7.5(Neutral)

357912

Soil Types

loamclaysilt

Drainage

moist

Water & Climate

Water Needs

High

Frost Tolerance

hardy

Time to Maturity

20–30 years

Care & Maintenance

Care Guide

Plant in full sun to partial shade in moist to wet, reasonably fertile soil. Oregon ash is one of the few large native trees tolerant of seasonally waterlogged soils — it is well-suited to rain gardens, bioswales, riparian restoration plantings, and low-lying areas where seasonal flooding occurs. Tolerates moderate drought once established on deep soils. Little maintenance required once established in appropriate conditions. Not suitable for restricted urban tree pits or areas with limited soil volume. Emerald ash borer (Agrilus planipennis) is an invasive pest currently expanding westward — monitor and consult current Pacific Northwest state extension guidance.

Pruning

Prune for structural form in the first five to ten years to establish a single central leader and well-spaced scaffold branches. Prune in late winter (February–March) when dormant. Remove dead, crossing, or structurally weak branches. Established trees require minimal pruning. Avoid pruning in late spring and summer when fresh wounds attract beetles.

Pruning Schedule

early spring

Maintenance Level

low

⚠️ Toxicity Warning

Non-toxic