What Problems Do Common Periwinkles Cause?

Some plants take the adage "go forth and multiply" entirely too seriously, and common periwinkle (Vinca minor) is one of them. Grown for its tough evergreen foliage that grows happily in shade in U.S. Department of Agriculture plant hardiness zones 4 though 9, common periwinkle also produces spring flowers that look like sapphire stars fallen from the sky. Unfortunately, periwinkle doesn't stay where it is planted for long.

Periwinkle, also called creeping myrtle, is a dream ground cover, with its evergreen foliage spreading fast and furious to create a thick mat. The leaves of this creeper are brilliant, glossy green and rise above the ground on 4- to 8-inch arching stems. The tubular, lavender-blue blossoms arrive in spring in the leaf axils and light up your yard for a solid month. Cultivars bloom more frequently. "Bowles" periwinkle (Vinca minor "Bowles") flowers from early spring through summer in USDA zones 4 through 9. Other cultivars produce violet flowers or variegated foliage.

Space periwinkle starter plants 5 feet apart and watch them go. They don't ask for much as long as you provide adequate water. They require a weekly watering and may need more in summer's heat. This evergreen thrives almost anywhere -- dry or moist soil, full sun, partial sun or deep shade. Trim back aging foliage to 4 inches in late winter or early spring to encourage vigorous new growth. To propagate common periwinkle, divide the roots in spring or fall.

Periwinkle is not a plant easily bullied by insect pests, diseases or other plants. It tolerates drought and repels deer. Like many plants, it is frequented by leafhoppers, scale insects and aphids, but none of these dampen its growth. Fungi affect common periwinkle, including Phomopsis livella and Pellicularia filamentosa, both of which cause roots to rot and shoot-tips to wilt. Fungi generally thrive in wet, dank conditions and often disappear in the summer as the sun dries foliage. The sole serious disease of common periwinkle is stem blight resulting from the fungus Phoma exigua var. exigua. The resulting dieback can kill the plant.

Common periwinkle's wanderlust causes problems for the neighborhood and the country. It is considered an invasive plant in some areas. It is a creeper, forming roots where stems touch the ground. It does not recognize your property limits and spreads aggressively into adjacent yards, lawns and garden areas. It also moves into nearby shady forests, forming extensive mats of ground cover near former plantings at old home sites and cemeteries. The dense cover crowds out native vegetation. The USDA Forest Service recommends manually digging out runners and applying chemicals -- general herbicides such as glyphosate -- in spring.