Appropriate to grow as a lush ground cover across USDA Hardiness Zones 4 through 9, the vine-like stems on the evergreen perennial sub-shrub called common periwinkle (Vinca minor) also goes by the name creeping myrtle or vinca vine. Blue-violet flowers occur if ample sunlight reaches the plant, but it grows lush in partially shaded spots under trees well if soil does not become bone dry.
Common periwinkle hails from the woodlands across Europe eastward into southern Russia and the northern Caucasus mountains.
Growing prostrate, this perennial sub-shrub's stems grow vine-like, sprawling to create a mat of dark green leaves with oval to elliptical shapes. These leaves persist across winter, adding to the beauty of the trailing stems when most other garden plants lie dormant. From mid-spring through autumn, stems receiving ample sunlight produce small blue-violet blossoms with five lobes. Variation of the flower color ranges from red-violet to pale blue or nearly white between individual plants.
Common periwinkle plants tolerate any soil type that does not become dry and excels in moist, well-draining soils that contain lots of organic matter. If soil remains evenly moist, grow these plants in full sun (receiving at least 8 hours of direct sunlight daily) which yields the best flowering displays. Periwinkle grows nicely in the partial shade under trees, too, where two to six hours of shifting sun and shade occur across the day. To reduce the mass of vining stems or restrict plant spread, severely prune them back hard in early spring before new growth begins.
Although common periwinkle makes an exceptional evergreen ground cover for woodland gardens, shrub borders or for shaded hillside stabilization, it grows voraciously in fertile, moist soils. This leads to exuberant stem growth and rooting of stems atop nearby soil, leading to invasiveness. In fact, two American states officially list this plant species as an undesirable and prohibited plant: Wisconsin and Tennessee, as noted by the U.S. Department of Agriculture's Invasive and Noxious Weeds Database.
Besides the wild species form of common periwinkle, several cultivars exist for use by gardeners wishing to have more ornate foliage forms or differently colored flowers. White flowers grow upon selections Gertrude Jekyll, Bowles White, natural form alba and the yellow and green variegated Alba Variegata. Violet-tinted blooms occur on Multiplex (Double Burgundy) and Atropurpurea (Rubra, Purpurea). Blue-tinted flowers reliably form on Azurea Flore Pleno (Caerulea Plena) and La Grave (Bowles' Blue). Argentovariegata (Variegata) and Ralph Shugert grow creamy white leaves with pale violet-blue blossoms.