How to Grow White Ash Trees

white ash tree

The Spruce / Autumn Wood 

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If you’ve ever held a wooden baseball bat, there’s a good chance you’re familiar with white ash. The white ash tree (Fraxinus americana) is native to the eastern portion of North America. It gets its name from the pale undersides of its otherwise deep green leaves, which turn a rich red, yellow, or purple in the fall. The tree also features grayish bark. Young white ashes start out with a somewhat pyramidal shape, and they grow at a moderate rate to eventually be more rounded and quite tall. Early autumn is the best time of year to plant a white ash. 

Botanical Name Fraxinus americana
Common Name White ash
Plant Type Deciduous tree
Mature Size 60 to 80 feet in height and spread
Sun Exposure Full sun
Soil Type Rich, loamy, moist, well-draining
Soil pH Neutral to slightly alkaline 
Bloom Time April to May
Flower Color Purplish
Hardiness Zones 3 to 9
Native Area Eastern North America
Toxicity Nontoxic
closeup of white mountain ash foliage
The Spruce / Autumn Wood 
white mountain ash foliage
The Spruce / Autumn Wood  
white mountain ash tree
The Spruce / Autumn Wood  

White Ash Tree Care

White ash trees grow naturally in hardwood forests of the United States and Canada and are often found along water sources. In landscape use, they are excellent large shade trees and are often seen lining city streets thanks to their tolerance for urban conditions. They prefer to be planted in a spot that gets a lot of light with fertile, moist soil. Providing your tree with the optimal planting site is key for its longterm care. 

The white ash is a fairly low-maintenance tree. Plan to fertilize annually and prune every few years, as well as prune problem areas such as broken branches as needed. Also, water as needed to maintain at least moderate soil moisture. And be on the lookout for signs of disease, which should be treated promptly.

Light

White ash trees grow best in full sun. This means they should be in a spot that gets at least six hours of direct sunlight on most days.

Soil

These trees prefer an organically rich loam soil with good drainage. The soil pH should ideally be neutral to slightly alkaline.

Water

White ash trees like even moisture in the soil (but not sogginess due to poor drainage). They can tolerate some drought, though prolonged drought can damage a tree. So water them during stretches without rainfall to maintain soil moisture. 

Temperature and Humidity

White ash trees thrive in the range of climates of USDA growing zones 3 to 9. They can handle temperatures several degrees below freezing, though frigid cold winters can damage the trees. However, healthy established trees tend to be fairly resilient to extreme weather, but they do prefer to be situated in a spot that is protected from strong winds. Moreover, humidity is not a concern to white ash trees as long as there is adequate soil drainage.

Fertilizer

White ash trees can benefit from an annual application of fertilizer each fall. It’s recommended to use an all-purpose tree fertilizer. Apply it according to label instructions under the tree’s canopy, and then water it into the soil.

White Ash Tree Varieties

There are several varieties of white ash trees, including: 

  • ‘Autumn Applause’: This tree features maroon fall foliage and notably dense branches. 
  • ‘Chicago Regal’: This is a fast-growing variety that has purple leaves in autumn.
  • ‘Greenspire’: This tree has a narrow, upright growth habit and turns dark orange in the fall.

Pruning

Pruning a white ash tree will both help to train the tree’s growth and help established trees remain healthy. Prune in the fall just after leaves start to drop. Young trees should be pruned annually while established trees should only need pruning every few years. 

On young trees, you will likely see several trunks, also known as leaders, growing. Select the strongest one and prune off the rest to ensure healthy upright growth. Plus, on both young and old trees, prune off any thin branches in the fall to improve air flow throughout the tree. And take off damaged, diseased, or dead branches as you spot them. Before disposing of any diseased portions, check with your local cooperative extension office to see whether there are any special procedures for the disposal.

Common Pests/Diseases

Gardening experts do not recommend planting white ash trees due to their vulnerability to the emerald ash borer (often seen abbreviated as EAB). It is an invasive beetle native to Asia that was first spotted in the Midwestern United States in 2002. It has since spread through several states and parts of Canada. Once the emerald ash borer infests a tree, it can quickly kill the tree within a few years. It bores into the wood where it feeds under the bark. It’s estimated to have killed millions of ash trees in North America so far, as the trees have very little resistance to the pest and eradication methods are typically unsuccessful. 

Dead leaves and premature fall leaf coloring are two signs of emerald ash borer infestation. You also might see dead branches around the tree’s crown, as well as new leaf shoots coming out of the trunk or branches. These shoots are a sign the tree is making an effort to produce extra leaves to help in photosynthesis. In addition, you might notice D-shaped holes in the tree, which are a telltale sign of a fully developed beetle boring out of the tree. Other lesions on the tree could be a sign of beetle larvae feeding. If you see any of these signs, consult with a professional arborist to see whether anything can be done to save the tree.

white ash tree with emerald ash borer damage
Tree with emerald ash borer damage rnkr / Getty Images