Periwinkle for Erosion Control

Description

• Each periwinkle grows between 4 and 6 inches tall, with a spread of 6 to 18 inches. The oval-shaped leaves are about .75 inches long and are a dark, glossy green. Vinca flourishes in full sun or part shade, but for erosion control purposes, it spreads and flowers most prolifically in full sun. The species bears large numbers of blue-purple flowers in mid-spring. Each bloom is twisted in the bud and opens into five petals, joined at the base to form a tube. The showy flowers, borne in the axils between leaf and stem, attract pollinators, including bees.

Erosion and Invasion

• Since its introduction in the 1700s, periwinkle has been used extensively as a ground cover and erosion controller. The plants have succeeded so well that they have outlived homesteads around which they were planted and the buildings on sites for which they provided erosion control. In much of the northeast, Texas and far west, periwinkle has spread into forests and other natural areas, forming mats and outcompeting native vegetation. Despite this, the species form and a number of cultivated varieties are still sold in nurseries and garden centers.

Substitutes

• Allegheny spurge (Pachysandra procumbens) can be used as a substitute erosion controller in part- to full-shade locations. Hardy in USDA zones 5 through 9, it grows somewhat more slowly than vinca, and the flowers are less showy. However, it can be very effective if the plants are installed close together at the beginning of an erosion control project. Yellowroot (Xanthorhiza simplicissima) is about 2 feet tall -- taller than periwinkle -- but just as vigorous and effective at erosion control in part shade. It features star-shaped purple flowers and is hardy in USDA zones 3 through 9.

Considerations

• Eradicating periwinkle, especially on slopes where it has been used for erosion control, can be difficult, since it must be thoroughly rooted out. When working with periwinkle, use caution, as all parts of the plant can cause gastric distress if ingested. Despite the species' beauty, status as a host for pollinating insects and utility as an erosion controller, avoid using it due to its invasive nature. The only acceptable way to cultivate periwinkle is in containers or beds with edgings that cannot be penetrated by the plants' roots.