Vinca (Vinca major) is an evergreen perennial with trailing branches and singular violet-blue flowers. It is winter hardy in U.S. Department of Agriculture plant hardiness zones 7 to 9. Native to the Mediterranean and central Europe, early settlers brought vinca to the United States for medicinal and ornamental purposes. Also known as Bigleaf periwinkle, Madagascar periwinkle, the plant can spread quickly if not properly controlled.
Vinca major thrives in morning sun and afternoon shade but tolerates full shade or full sun. It grows best in moist, loamy, well-drained soil with neutral to acidic pH. Not tolerant of drought, the plant requires water one to two times each week. As a ground cover for a large area, space starter plants 12 to 18 inches apart. For small areas, set plants 8 inches apart.
Vinca grows 12 to 18 inches tall and spreads as a ground cover indefinitely. Gardeners use large periwinkle for ground cover or as a container accent because its trailing characteristic lends beauty when placed in window boxes or cascading down stone walls. Thanks to its interweaving vines, it quickly covers ground while choking out weeds. Once established on an embankment, Vinca major helps prevent erosion. The plant also holds it own against deer, resisting severe damage from hungry animals.
Large periwinkle easily roots and spreads from pieces of stems on the ground. It overcomes and eradicates existing plants as it expands. The best method of containment is hand pulling the plants found in undesirable areas. Remove the entire plant with all its roots and stems for the best result.
As an alternate method of control, use the chemicals glyphosat or triclopyr. Glyphosat is a nonselective systemic herbicide that kills all vegetation where applied. Triclopry only kills broadleaf species and does not bother grasses.
Mix 2.5 ounces of glyphosat or triclopyr in 1 gallon of water. Pour into a hand-held sprayer. Apply a light layer of the herbicide over all plant stems and leaves.
Vinca major 'Wojo's Gem' offers creamy yellow leaves with deep green edges. _Vinca major '_Elegantissima' produces a variegated leaf also with dark green centers and pale yellow edging. Both of these cultivars feature the traditional blue-violet flower.
For a vinca-lookalike that is not invasive, try a plant in the genus Catharanthus. Frequently referred to as vinca, these flowering perennials only grow 8 to 18 inches tall and 1 foot wide, with the trailing Catharanthus varieties not exceeding 2 feet wide.
Gardeners often call Catharanthus roseus the rose periwinkle. Winter hardy in USDA plant hardiness zones 9 to 11, this species boasts rose pink petals and dark green, glossy leaves. C. roseus '_Morning Mist' produces large white flowers with dark pink centers. Cultivars of _Catharanthus roseus offer an array of flower colors such as pale pink, hot pink, rose, red and lilac, often with darker centers.