The hoptree (Ptelea trifoliata) is a deciduous shrub that’s native to North America, growing naturally in woodlands, prairies, ravines, rocky bluffs, and more. This adaptable shrub can get fairly large with a dense, rounded growth habit. And many people take advantage of that dense foliage by using it as a privacy hedge, even though the shrub drops its leaves for the winter.
Hoptree leaves are composed of three ovate leaflets that are a glossy dark green color before turning to greenish-yellow or golden in the fall. The shrub’s bark is a reddish-brown to gray-brown color. In the late spring, clusters of small greenish-white flowers appear, attracting butterflies and other pollinators. But overall, the plant is grown for its foliage. The shrub’s flowers, along with its foliage and bark when crushed, give off a musky, slightly lemony odor. Some people find it unpleasant while others don’t mind it. Hoptree has a slow growth rate and is best planted in the spring or fall.
|Common Names||Hoptree, common hoptree, stinking ash, skunk bush, wafer ash, swamp dogwood|
|Botanical Name||Ptelea trifoliata|
|Mature Size||15–20 ft. tall, 15–20 ft. wide|
|Sun Exposure||Partial, shade|
|Flower Color||Green, white|
|Hardiness Zones||4-9 (USDA)|
|Native Area||North America|
Hoptree is a very versatile shrub that can adapt to many different growing conditions and doesn’t require much maintenance to keep it healthy. It typically needs only minimal pruning each year. And the shrub doesn’t have any serious issues with pests or diseases. It is notably deer resistant, yet its seeds provide food for birds and other wildlife.
When planting, be sure to select a site that has good soil drainage and can accommodate the mature size of the shrub. In general, plan to water your hoptree during dry spells and feed it annually.
The shrub is commonly an understory plant in the wild, growing in sunlight that’s diffused by tall trees. Thus, it thrives in spots that get partial sunlight, meaning around three hours of direct sunlight on most days. It is also tolerant of even shadier conditions as well as of spots that get more sunlight if its moisture needs are met. However, harsh afternoon sun can scorch the shrub's foliage.
Hoptree grows well in a variety of soil types, including sandy, rocky, loamy, and even somewhat slow-draining clay soil. But it prefers loamy soil that is rich in organic matter and has good drainage. Plus, it likes a relatively neutral soil pH.
Hoptree shrubs growing in shady conditions have moderate to low water needs. On the contrary, hoptree shrubs that get a lot of sun should have evenly moist (but not soggy) soil. The shrub does have some drought tolerance. So when grown in partial sunlight conditions, you’ll likely only have to water during prolonged dry spells or very hot temperatures. However, the soil on young hoptree shrubs should be kept consistently moist as they develop their root systems.
Temperature and Humidity
Hoptree shrubs can tolerate the wide range of temperatures within their growing zones quite well. However, frost and unseasonably cold temperatures can damage tender new growth in the spring. Humidity typically isn’t an issue. In very high humidity, good airflow around the shrub will help to prevent fungal diseases. And in very low humidity, make sure the shrub’s soil stays moist. A layer of mulch around the plant can help to retain soil moisture.
Hoptree shrubs prefer to grow in organically rich soil, but they also can thrive in average soil. Perform a soil test to determine any deficiencies and what kind of fertilizer would be needed to address them. For the amount to use, follow the product label instructions. Also, mixing some compost into the soil, especially at the time of planting, can promote healthy growth.
Types of Hoptree
There are numerous varieties of hoptree that vary slightly in appearance, including:
- Ptelea trifoliata ‘Aurea’: This variety features golden leaves that mature to a bright lime green color.
- Ptelea trifoliata ‘Glauca’: This shrub has blue-green leaves that turn yellow in the fall.
- Ptelea trifoliata ‘Fastigiata’: This variety is known for its upright growth habit and is good for narrow spaces.
Hoptree does not need extensive pruning to keep it looking tidy. If necessary, prune your hoptree over the winter while it’s dormant to clean up its shape. Remove any dead, damaged, or diseased portions as they arise. If you wish to promote more branching, cut back the stems by no more than 1/3 of their full length just above a leaf node. And to prevent unwanted spread, remove suckers (stems growing up from the base of the plant).
Hoptree can be propagated by softwood cuttings or seeds. To take a softwood cutting from the hoptree, wait until early spring when new growth is appearing.
- Choose a stem with no buds or flowers. With sharp, clean pruners, cut a 6-inch piece of stem and remove the lower leaves.
- Dip the cut end into rooting hormone, and plant the cutting 2 inches deep in a pot filled with moist yet well-draining potting soil. You can plant more than one cutting in the same pot, as not all of them will survive.
- Keep them indoors or outside in a sheltered area until roots begin to form. When the new plants are strong enough to grow new leaves, plant them in your chosen spot.
How to Grow Hoptree From Seed
To grow a hoptree from seed, allow the seed pods to dry on the tree, then open them up to remove the tiny seeds inside. Place the seeds in a small container with dampened vermiculite and place the container in the refrigerator for three months to cold stratify the seeds. In the spring, remove the seeds from the refrigerator and plant them about 1 inch deep in rich potting soil. Put the container in a warm, sunny location and look for germination in three to four weeks.
While mature shrubs are hardy, young shrubs should be protected from late frosts in the spring with a burlap sheet or other cover.
Common Pests and Plant Diseases
Hoptree doesn't often have issues with plant diseases, though it might occasionally suffer from rust, leaf spot, and tree hoppers. Tree hoppers are unique-looking insects that eat the sap from the tree but rarely do any significant damage. However, if you want to remove them, a mild insecticide will do the trick. To treat rust or leaf spot, use an appropriate fungicide.
It's important to note that the hoptree is home to several types of butterflies, including some quite rare species. The small butterfly caterpillars might munch on the leaves but rarely are there enough of them to do any real damage. Rather than remove them, it's best to leave them alone and enjoy the butterfly show in the coming months.
What makes hoptree so special?
Hoptree is a larval host plant for the rare Giant Swallowtail butterfly. If you want to draw butterflies to the yard, this is the best shrub to make it happen.
Can hoptree grow indoors?
Though hoptree can be started from cuttings indoors and kept inside for a brief season, this shrub needs the ample room only the outdoors can provide.
What are the "wafers" of a hoptree?
The tan, flat "wafers" appear on the tree after the blooms fade. Wildlife love to eat them. These bitter wafers were sometimes used as an alternative to hops when brewing beer.