Green Ash (Fraxinus pennsylvanica) - How to Grow & Care Guide

Plant Snapshot

Common Name: Green Ash
Latin Name: Fraxinus pennsylvanica
Alternate Names: Red ash, swamp ash
Hardiness Zones: USDA zones 3 to 9. Colder zones may show slower growth or winter dieback. Warmer zones may promote more vigorous growth and suckering.
Typical Height: 40 to 60 ft (12 to 18 m) mature height typical in landscape settings
Typical Spread: 30 to 50 ft (9 to 15 m) spread at maturity
Bloom Period: Spring, typically flowering before or with leaf emergence
Soil Preferences: Prefers moist, well drained soils but tolerates wet or compacted clay and occasional flooding
Light Preferences: Full sun to part shade
Toxicity: Not widely documented as highly toxic to humans or pets. Verify with ASPCA or local poison control before assuming safety.
Propagation: Seed from winged samaras and natural root suckering. Cultivars propagated by grafting or cuttings as needed.

Key Facts

Native to eastern and central North America
Deciduous shade tree with an upright vase to rounded crown
Dioecious with separate male and female trees
Produces winged samaras for seed dispersal
Tolerates wet soils and compacted urban sites
Commonly used as a street and shade tree
Highly susceptible to emerald ash borer which can cause rapid decline

Green Ash (Fraxinus pennsylvanica) is a fast growing North American shade tree valued for its adaptability to wet and urban soils. It provides reliable street and yard shade but is highly vulnerable to emerald ash borer which can cause rapid decline.

Identification

Deciduous tree with an upright vase to rounded crown and pinnate leaves. Trees are dioecious so male and female trees are separate and only female trees produce winged samaras. Mature height is typically 40 to 60 feet with a spread around 30 to 50 feet in landscape settings.

Where to grow and best uses

Performs across USDA zones 3 to 9 and is commonly used as a street and shade tree. It tolerates compacted urban soils and wet spots so it suits city planting strips and yards with clay or occasional flooding. Avoid sites where the emerald ash borer is present unless you have a management plan.

Planting and spacing

Allow space for the mature crown by planting trees about 30 to 50 feet apart depending on cultivar and site. Choose a location with full sun to part shade and avoid long term poorly drained depressions. Match hole size to the root ball and set the root flare visible at the finished grade.

Water and soil

Prefers moist well drained soils but tolerates wet or compacted clay and occasional flooding. Prolonged saturation will reduce vigor so improve drainage for long term health. In urban sites mulch to conserve moisture and reduce compaction but keep mulch pulled slightly away from the trunk to avoid rot.

Maintenance and pests

Prune young trees for a strong central scaffold to reduce future storm damage. Monitor for emerald ash borer as this pest can cause rapid decline and mortality. Severely infested trees should be removed promptly to reduce hazard and limit spread if local authorities recommend removal.

Propagation and spread control

Propagates from seed produced in winged samaras and commonly sends up root suckers. Named cultivars are usually propagated by grafting or cuttings since seedlings do not reliably come true to type. Manage unwanted suckers by removing them at the root to prevent thicket formation.

Frequently asked questions

How fast does Green Ash grow?: Green Ash is considered fast growing and typically reaches a mature height of 40 to 60 feet in suitable sites depending on soil and climate.
What hardiness zones suit Green Ash?: Green Ash performs broadly in USDA zones 3 to 9 which covers much of eastern and central North America.
Is Green Ash good for wet sites?: Yes. It tolerates wet or compacted soils and occasional flooding but prolonged saturation reduces vigor so improved drainage is advised for long term health.
How far apart should I plant Green Ash?: Space trees about 30 to 50 feet apart to accommodate a mature crown and reduce future crowding in landscapes or along streets.
Does Green Ash produce seeds?: Yes. Female trees produce winged samaras that disperse by wind. The species is dioecious so only female trees set seed.