Petrea is a genus of tropical flowering vine, in the Verbenaceae, or verbena, family. Plants in this genus are native to northern Mexico, Central America, the Caribbean, Brazil, and western South America. One of the most popular species, Petrea volubilis, makes a charming addition to hanging baskets, trellises, pergolas, fences, or other landscaping features that allow it to climb or hang. Propagation may be carried out with cuttings or seeds. Although this genus of plant is not susceptible to serious insect or disease problems, it may attract mold, scale, mealybugs, and, to a lesser extent, spider mites.
The Petrea volubilis species is also known as purple wreath, queen's wreath, and sandpaper vine. In the wild, it may reach a height of 30-40 feet (9-12 meters), but in captivity it may be trained to be much shorter. Petrea tolerates United States Department of Agriculture Hardiness Zones 10 and 11. This means that the lowest temperature in which it will survive is 30° Fahrenheit (-1.1° Celsius). This genus prefers full sunlight to partial shade.
From late winter or early spring through late summer or early fall, Petrea produces star-like flowers in various shades of blue-violet, ivory, or white. The leaves are oblong, between 4-9 inches (10-23 centimeters) long, and evergreen. The tops of the leaves are rough, which is why some people refer to the plant as sandpaper vine. Plants in this genus have average water needs. Care should be taken not to overwater.
Petrea may be grown in garden beds on a trellis, in containers, or in hanging baskets. It is a fast-growing woody plant that some say looks similar to a wisteria. In cold climates, Patrea must be brought indoors to overwinter.
New plants may be propagated from woody stem or semi-hardwood cuttings. They may also be grown from seed. Seeds can be started indoors prior to the last frost of the season or sewn outside following the last frost.
Overall, Petrea species are healthy. They are susceptible, however, to mold and scale. Removal or quarantine of sick plants and a fungicide may be used to control these conditions. Mealybugs may be picked off by hand if there are not too many or plants may be sprayed with a homemade alcohol-based mealybug insecticide. Spraying the plant with neem oil, along with the introduction of lady bugs or other insects that prey on spider mites, will help gardeners manage any mite infestations.