Key Facts
- Large native North American shade tree
- Pinnately compound leaves with 7 to 9 leaflets
- Distinctive furrowed bark that becomes diamond patterned with age
- Showy yellow to purple fall color in many specimens
- Blooms in spring before or as leaves emerge with small purple to purplish green flowers
- Prefers moist, well drained soils but tolerates clay and some drought
- Thrives in full sun to part shade
- Highly susceptible to emerald ash borer which can cause rapid decline
- Commonly grown from seed or propagated by grafting for named cultivars
White Ash is a large native North American shade tree prized for pinnate leaves and strong fall color, yet its future is threatened in many areas by emerald ash borer.
Identification
Leaves are pinnately compound with seven to nine leaflets and bark that develops deep furrows and a diamond pattern with age. Small clusters of purple to purplish green flowers appear in spring before or as leaves emerge. Many specimens show showy yellow to purple fall color that helps identify mature trees in autumn.
Best uses and where to grow
Use White Ash as a park or large yard shade tree where there is room for a wide crown. It thrives in full sun to part shade and is hardy in USDA zones 3 to 9. It prefers moist well drained soils and tolerates clay and periodic dry spells but will decline in waterlogged sites.
Planting and spacing
Allow room for a mature crown that commonly spreads 35 to 50 feet. Space single specimens at least as far apart as the expected mature spread to avoid severe crown competition. Urban constraints and root competition will reduce spread and may require selecting a different species for tight sites.
Planting season
Plant during a dormant season that matches your climate, often in spring or fall. Planting while the tree is dormant improves establishment and reduces transplant stress. Adjust timing for local frost dates and soil workability as needed.
Watering and soil
White Ash prefers consistently moist well drained soil. Poorly drained or waterlogged soils cause decline and extended drought increases stress and susceptibility to pests. Maintain steady moisture during establishment to promote root development and reduce risk of stress related decline.
After flowering care and pruning
After flowering focus on reinforcing tree health by maintaining soil moisture and removing damaged or dead wood. Prune young trees to develop a balanced crown and reduce structural defects. Major pruning is usually done during dormancy to reduce stress and improve wound response.
Pests and long term management
White Ash is highly susceptible to emerald ash borer which can cause rapid decline and death. Check with local extension for presence of this pest and consult a certified arborist before using treatments. In areas with established infestations plan for monitoring and replacement with resistant species.
Propagation and nursery notes
Species trees are commonly grown from seed and named cultivars are propagated by grafting or budding. Trees can produce root suckers. Softwood cuttings root poorly for many selections and seed germination typically requires stratification to break dormancy.
Frequently asked questions
- How fast does White Ash grow?
- Growth rate varies with site fertility and moisture. Trees commonly reach 50 to 80 feet at maturity with faster growth on fertile moist sites and slower growth in colder or dry areas.
- Is White Ash suitable for small yards?
- No. Mature height and a 35 to 50 foot crown make it best for large yards parks and open landscapes rather than small confined spaces.
- How can I tell if my White Ash has emerald ash borer?
- Look for thinning crown epicormic sprouts bark splitting and D shaped exit holes in stems. Confirm with local extension or an arborist because symptoms can vary by site and health of the tree.
- Can I grow White Ash from seed?
- Yes. Seed propagation is common for species trees and usually requires cold stratification for reliable germination. Named cultivars are propagated by grafting or budding.
- Is White Ash toxic to pets?
- Fraxinus species are not generally listed as toxic to dogs and cats but pollen can trigger seasonal allergies and handling may irritate sensitive skin. Verify current listings with poison control or the ASPCA for local guidance.
Related Plants
