Native to North American woodlands, hop tree is an easy-to-grow large shrub or small tree that thrives equally well in sun or shade. A small tree maturing at around 20 feet in height, it is the hardiest member of the citrus family, growing as far north as Zone 4. Hop tree has a large geographic range and is found scattered throughout the eastern half of the U.S., from Ontario and New York to Florida and west to Minnesota. Curiously, it is also found in parts of the Southwest. It is a natural choice for anyone looking for a dependable understory tree to plant beneath a high-branched shade tree.
Also called wafer ash or water ash, hop tree gets its more common name from the bitter, aromatic fruit, which were said to be tested as a substitute for hops in the making of beer.
Hop tree has large leaves consisting of several individual leaflets that resemble those of the ash tree. They're shiny, dark green on top, pale and hairy beneath, and they turn greenish yellow in autumn. Hop tree's aromatic, greenish white flowers are rather inconspicuous, appearing in early summer. They're usually followed by showy seeds that have more prominence because they're surrounded by papery wings that give them a waferlike appearance. Seeds mature from bright green to brown, staying on the tree through fall and winter, when they serve as food for wildlife.
This modest-size tree pairs well with showy companions, particularly those with darker foliage, such as varieties of ninebark, smokebush, purpleleaf sandcherry, 'Forest Pansy' redbud, and chokecherry. If growing it in the shade, substitute shade lovers like azalea, rhododendron, ferns, and myrtle.
Hop tree's spreading, multistem shape is attractive, but it responds well to hard pruning if a more formal look is desired. Adaptable to different lighting conditions, hop tree can be grown as a small ornamental, an understory tree, or part of a natural hedgerow or shelterbelt. The lustrous leaves, showy seeds, and chestnut brown bark on young stems are attractive enough to warrant a place in a larger shrub bed.
The fragrant flowers on the hop tree attract pollinators, including bees and butterflies, and it is a food source for caterpillars of the giant swallowtail butterfly.
Hop Tree Care Must-Knows
Hop tree is adaptable, growing easily in a variety of soil types—including slow-draining clay and fast-draining sandy loam—but it does best in moist soil with plenty of organic matter. Hop tree has no serious pests or diseases. It is best planted or transplanted when dormant, either in early spring or late fall. Pruning should be done when the plant is dormant, removing dead or broken branches and improving the shape. The tree does tend to sucker, so you may need to remove newly formed stems arising from the ground.
Cultivars of Note
'Aurea' has yellow leaves that mature to lime green. Ptelea trifoliate var. bailey boasts white bark. An upright grower for confined spaces, 'Fastigiata' is another cultivar. Blue-green leaves decorate 'Glauca'.