Culture
Easily grown in most soils. Best in lean to average soils with regular moisture in full sun. Lean soils help restrain growth. Will grow in part shade, but needs full sun for best flowering and subsequent fruit display. Prune in late winter to early spring. Mature vines require little pruning other than removal of dead or excess growth. These plants are primarily dioecious (separate male and female plants), although some plants have a few perfect flowers. Female plants need a male pollinator to produce the attractive fruit that is the signature of this vine. Unfortunately, some nurseries do not sell the vines as male or female (as is commonly done with hollies). Generally one male plant is needed for 6-9 female plants. Female plants may be vegetatively propagated to create more female plants. Vines may be grown on structures or allowed to ramble along the ground. It is generally best to avoid growing vines up small trees or through shrubs because vines grow rapidly and can girdle trunks and branches causing damage and sometimes death. Vines sucker at the roots to form large colonies in the wild. Vines will also aggressively self-seed, often with assistance from local bird populations.
Notwithstanding its ornamental assets, this plant is considered to be an invasive weed in many parts of the eastern U.S. because of its ability to spread aggressively in the landscape. Michael Dirr recommends that this plant “needs to be outlawed as a real biological gun-slinger (seed disperser).”
Noteworthy Characteristics
Celastrus orbiculatus, commonly known as Chinese bittersweet or oriental bittersweet, is a perennial, deciduous, twining woody vine that can grow to 60’ long or more with a stem diameter of up to 4”. Growth habit is climbing and/or sprawling. It is native to Korea, China and Japan, but was introduced into the U.S. around 1860 as an ornamental vine. It has escaped cultivation in the eastern U.S. since its introduction and has naturalized in a variety of locations including mixed hardwood forests, forest margins, fields, old homesites, and road margins. It is currently included on a number of invasive species lists. Ornamental attributes include (a) brown straited bark, (b) alternate elliptical to circular light green leaves (2-5”) which turn yellow in fall, (c) small, inconspicuous, greenish white flowers in clusters of 3-7 bloom May to early June, and (d) small, globose, pea-sized fruits which emerge green when young but ripen to yellow before splitting open in fall to reveal showy scarlet berries that persist into winter.
This vine closely resembles American bittersweet (Celastrus scandens), but the main differences are that C. scandens has its flowers and fruits located at the branch ends, whereas C. orbiculatus has its flowers and fruits located in the leaf axils. In addition, C. orbiculatis is much more invasive in the landscape.
C. orbiculatus is a fast-growing vine that can easily cover, shade and outcompete other vegetation. It can girdle and kill large trees. Birds and other wildlife eat the berries and distribute the seed. This vine hybridizes with the native American C. scandens to produce plants with viable seed, which suggests possible loss of genetic identity for the native species over time.
Genus name comes from the Greek word kelastros for an evergreen tree.
Specific epithet comes from the Latin orbiculatus meaning disc-shaped.
Problems
No serious insect or disease problems. Euonymus scale and two-marked treehoppers may cause significant damage in some areas.
Uses
Chinese bittersweet should not be planted in the eastern or midwestern U. S. because of invasive potential.
Where appropriate, it can be an interesting addition to woodland gardens and naturalized areas. Provides quick cover for fences, arbors, trellises, posts, walls or other structures in the landscape. Also may be grown along the ground to camouflage rock piles or old tree stumps.