The Cathedral Elm is a hybrid elm cultivar widely appreciated for its resilience and ability to provide substantial shade. It offers a combination of desirable traits, making it a popular selection for various landscapes. This robust choice is ideal for those seeking a durable and attractive shade tree.
Understanding the Cathedral Elm
The Cathedral Elm (Ulmus ‘Cathedral’) is a hybrid cultivar developed at the University of Wisconsin. It originated from a cross between the Japanese elm (Ulmus parvifolia) and the Siberian elm (Ulmus pumila). This parentage gives it unique characteristics, including tolerance to challenging urban conditions and fast growth.
This tree typically exhibits an upright, spreading habit, forming a broad vase-shaped canopy. It reaches a mature size of 40 to 60 feet in height and spread. Its dark green, serrated leaves provide a dense canopy throughout the growing season, turning yellow in autumn before dropping for winter.
Key Advantages of Cathedral Elms
A primary advantage of the Cathedral Elm is its strong resistance to Dutch Elm Disease (DED). The tree can often wall off infections, preventing spread and making it a reliable choice where DED has been a concern.
Cathedral Elms boast a rapid growth rate, often adding five to six feet in height annually under ideal conditions. This allows for quick establishment and development of a substantial shade canopy. The tree adapts to various soil types and urban environments, tolerating dry or moist locations, a range of soil pH, urban pollution, and environmental salt. This makes it suitable for city boulevards and challenging sites.
Beyond its durability and adaptability, the Cathedral Elm offers significant aesthetic appeal. Its classic form and dense canopy create an impressive landscape presence, providing ample shade. Its reliable yellow fall color adds seasonal interest, making it a superb choice for shade or street tree applications.
Planting and Care Essentials
Successful establishment begins with proper site selection. The tree thrives in full sunlight, requiring at least six hours of direct sun daily. While adaptable to various soil conditions, it prefers well-drained soil but tolerates clay, loam, and sand. Given its large mature spread, plan for adequate space, ensuring it is planted away from power lines and structures.
When planting, dig a hole at least twice as wide as the root ball, but only as deep. Ensure the root flare, where the trunk widens at the base, is at or slightly above ground level. Loosen the soil at the bottom and sides of the hole to encourage root expansion. Backfill with excavated soil, potentially amended with compost, and water thoroughly to settle the soil around the roots.
Consistent watering is important for the first year or two as the tree establishes its root system. Young trees require regular, deep watering, especially during dry periods, if natural rainfall is insufficient. Once established, Cathedral Elms become more drought-tolerant but still benefit from deep watering during prolonged dry spells.
Pruning should occur during the dormant season, typically late winter (December through March). For the first 10 to 15 years, regular structural pruning develops a strong framework and maintains the tree’s vase shape. Focus on removing dead, damaged, or crossing branches to promote healthy growth and air circulation. Lower branches can be gradually removed over several years for desired clearance beneath the canopy.
For newly planted trees, wait until the following spring to apply fertilizer. A balanced fertilizer, such as a 10-10-10 or 20-20-20 N-P-K ratio, works well, though some sources suggest a slightly higher nitrogen content like 10-6-4. Apply fertilizers in granular or liquid form in late fall after leaf drop or early spring before buds break. Always water the tree before and after fertilization to aid absorption and prevent root burn. Avoid over-fertilizing, as established trees may not require annual applications.
Important Considerations for Growing Cathedral Elms
While Cathedral Elms exhibit strong resistance to Dutch Elm Disease, no tree is entirely immune. Other pests and diseases can still affect them, though generally less severely. For example, elm leaf beetles and leafhoppers can be a concern.
The Cathedral Elm’s substantial mature size requires careful placement. It needs ample space to grow without conflicting with structures, overhead power lines, or other trees. Sufficient room for its root system is also important for long-term health and stability. As a deciduous tree, it sheds its leaves in the fall, a natural part of its seasonal cycle.