How to Grow and Care for a Red Ash Tree

The red ash, known botanically as Fraxinus pennsylvanica, is a resilient and widely distributed hardwood tree native to North America. Often referred to by other names, including green ash, it is a fast-growing deciduous tree appreciated for its adaptability to a range of environmental conditions. The tree is characterized by its straight trunk and an oval or rounded crown that provides ample shade.

Red Ash Tree Identification

The leaves are pinnately compound, meaning they consist of multiple leaflets arranged on either side of a central stalk. Each leaf has five to nine leaflets. These leaflets are elliptic or lance-shaped, measuring two to five inches long, and have smooth or finely toothed edges. The upper surface is a matte dark green, while the underside is a lighter green.

The bark of a mature red ash displays a thick, gray-brown surface with a pattern of interlacing ridges that form distinct diamond shapes. On younger trees, the bark is smoother and grayer. A key identifier for red ash is the texture of its new growth, as the twigs, new shoots, and leafstalks are covered in fine, velvety hairs, a characteristic known as pubescence.

In the spring, the tree produces small, inconspicuous flowers that are pollinated by the wind. These are followed by the development of seeds, called samaras, which are encased in a single, elongated wing. The samaras hang in drooping clusters and mature in late summer and fall, changing from green to tan as they ripen. A mature red ash can reach heights of 50 to 70 feet, forming an oval or rounded crown.

Distinguishing Red Ash From Green Ash

Confusion often surrounds the red ash due to its close relationship with the green ash. Modern botanical classification no longer considers them separate species but rather varieties of the same species, Fraxinus pennsylvanica. Red ash is designated as Fraxinus pennsylvanica var. pennsylvanica, while green ash is Fraxinus pennsylvanica var. lanceolata.

The most reliable feature for distinguishing the two varieties is the presence or absence of fine hairs, or pubescence. Red ash is defined by the velvety texture on its new twigs, leafstalks, and the undersides of its leaflets. In contrast, the green ash variety is glabrous, meaning these same parts are smooth and free of hairs. This difference requires close inspection.

Both varieties have the same overall form, with a comparable height and crown shape, and their bark develops the same characteristic diamond-shaped ridges with age. Because these more prominent features are shared, distinguishing between red and green ash often comes down to feeling the texture of a young twig.

Natural Habitat and Growing Conditions

The red ash has an extensive native range across eastern and central North America. It stretches from Nova Scotia west to Alberta, Canada, and extends south through the United States to northern Florida and eastern Texas.

This tree naturally thrives in moist environments, making it a common sight along riverbanks, in floodplain woodlands, and across bottomlands. It is well-suited to soils that experience occasional to frequent flooding, particularly during its dormant season.

While it prefers moist, well-drained loamy or silty soils, it can tolerate a variety of soil types, including heavy clays and drier sandy soils. For healthy development, the red ash requires a location that receives full sun to light shade. This hardiness made it a go-to species for challenging sites where other trees might struggle to survive.

Planting and General Care

The tree performs best in a location that receives full sun, as this promotes vigorous growth and a dense canopy. Provide ample space to accommodate its mature size to prevent future conflicts with buildings or other trees.

For planting a young tree, the hole should be dug two to three times wider than the root ball but no deeper, ensuring the top of the root ball is level with the surrounding soil. After placing the tree in the hole and backfilling, water it thoroughly to settle the soil and eliminate air pockets. Consistent moisture helps newly planted trees establish a strong root system.

Pruning is minimal and best performed in late winter or early spring while the tree is dormant. The goal of pruning is to remove any dead, damaged, or crossing branches to maintain the tree’s structural integrity. Due to its fast growth rate, establishing a strong branching pattern early can help prevent weak limbs from developing.

Common Pests and Diseases

The greatest threat to all North American ash trees, including the red ash, is the emerald ash borer (EAB). This invasive metallic green beetle, native to Asia, was first detected in North America in 2002 and has since decimated ash populations. The adult beetles cause minor damage by feeding on leaves, but the larvae are the primary cause of mortality. They feed on the inner bark, creating S-shaped galleries that disrupt the tree’s ability to transport water and nutrients.

One of the first symptoms of an EAB infestation is canopy dieback, starting at the top of the tree and progressing downward. Other indicators include:

• Small, D-shaped exit holes in the bark where adult beetles have emerged
• Vertical splits in the bark
• Increased woodpecker activity as they feed on the larvae
• Leafy shoots, or epicormic sprouts, emerging from the lower trunk

Without intervention, an EAB infestation is almost always fatal to the tree, often within three to five years. Managing the pest requires preventative insecticide treatments, which can be applied as trunk injections or soil drenches. These treatments can be costly and must be applied every one to three years, making them a long-term commitment. Besides EAB, red ash can also be affected by ash yellows, a disease that leads to gradual decline, and fungal issues like anthracnose, which causes leaf spots.

Uses of the Red Ash Tree

The wood of the red ash has a combination of strength, light weight, and shock-absorbent properties. These characteristics make it a choice for products requiring durability and flexibility, such as:

• Tool handles
• Baseball bats
• Oars
• Hockey sticks

The wood’s attractive grain also made it a popular material for furniture, cabinetry, and flooring.

Before the devastation caused by the emerald ash borer, the red ash was one of the most popular landscape trees in North America. Its fast growth rate, good form, and tolerance of difficult urban conditions like poor soil and pollution made it an ideal choice for street and shade trees.

The red ash provides value to wildlife. Its seeds are a food source for numerous bird species, including finches, cardinals, and wild turkeys, as well as squirrels. The tree offers cover and nesting sites for birds like owls and hawks, and its leaves serve as a food source for the larvae of various butterfly and moth species.