Campsis is a genus of two species of plants in the Bignoniaceae, or bignonia, family. These plants are vines and are known for their large, trumpet-shaped flowers. Both species form very large vines and are grown horticulturally for their flowers, large seed pods, and distinctive leaves. Trumpet creeper or trumpet vine — or Campsis radicans — which is native to the United States, can be an aggressive weed that can tear the siding off a house. It can also invade corn and soybean fields, greatly reducing yields.
Campsis grandiflora is known as the Chinese trumpet vine. It is native to Asia. This species is less hardy than the American trumpet vine, which can grow at temperatures down to -30°F (-34°C). The Chinese trumpet vine can grow to 30 feet (9 m) under ideal conditions. It is sometimes grown in preference to Campsis radicans, because the Asian vine has larger flowers that are more red in color.
Trumpet vine is not fussy about soil, as long as it is not constantly wet. In many parts of the United States and southern Canada, the plant is drought-tolerant. In desert areas, however, it needs some supplemental water. This vine does require full sun, or it will not bloom well.
Campsis radicans produces 2-3 inch (5-7.5 cm), trumpet-shaped flowers that are generally bright orange. Hybrids have been developed that produce red or yellow flowers. The plants start blooming after the weather has been consistently warm for several months, generally in early summer, and bloom throughout the season. Highly noticeable, large, long, pointed seedpods are also produced. The 1 to 3 inch (2.5 to 7.5 cm) long, deciduous leaves are dark green with 7 to 15 leaflets, and range from ½ to 1½ inch (1.25 to 3.75 cm) wide.
Trumpet vine can grow to be 35 feet (10.5 m) long. It produces tendrils to help it climb. If there is no support to climb on, the vine will grow over the landscape as a ground cover. The stems will root wherever they touch the ground. The plants also develop suckers.
It can be very difficult to eradicate trumpet vine from a yard once established. It can grow over trees and houses, and can attract ants. The best place to grow it is in a container or on an arbor or trellis. It should be pruned heavily.
This species of Campsis can be a problem weed in agricultural fields of crops like corn or soybeans. This is particularly a problem in no-till production, where agricultural practices do not involve cultivation of the soil. Infestations can be greatly minimized when the soil is tilled, and then herbicides are used.
Trumpet vine can be an attractive vine for landscaping, as long as one is aware of its shortcomings. Precautions must be taken against its spread. If this is done properly, a gardener can have the trumpet-shaped flowers without fending off an aggressive weed. One advantage of this vine is that it attracts hummingbirds.