Gardening is usually rewarding, but sometimes you discover a spot of ground where it's difficult to have both greenery and color. Vinca (Vinca spp.), also called periwinkle, can be the ideal problem-solver to fill in these areas. It's usually problem-free, simple to grow and adaptable to most light conditions. Two types exist, called lesser and greater periwinkle, with slightly different features.
The smaller, or lesser, type of periwinkle (Vinca minor) is about 3 to 6 inches tall, spreads to cover an area of about 1 1/2 feet and makes a useful groundcover. It's a hardy evergreen that grows in U.S. Department of Agriculture plant hardiness zones 4 through 8.Greater periwinkle (Vinca major) is taller, about 6 to 18 inches in height, and it spreads to a width of about 2 feet. Also an evergreen, it's a bit more tender than the smaller form and grows in USDA zones 7 through 9.
Both types of vinca plants are quite tolerant of different light conditions and can thrive in either full sun or partial shade. They can grow well in full sun, but in hot climates with strong summer sun they prefer some light shade in the afternoon, which helps prevent scorching of their foliage. The plants also grow in filtered, shifting shade that spans the entire day and can tolerate deeper shade if other growing conditions are ideal.
Foliage and Flowers
The amount of sun a periwinkle plant receives can influence its performance and development of its features. When the plant is grown in partial shade, its small, pointed oval leaves develop a deep green color, and variegated cultivars with white- or yellow-accented leaves develop especially pleasing color contrasts in their foliage. Both greater and lesser periwinkle plants have showy, bluish-violet flowers, but flower production also depends on light, with more blossoms produced on plants grown in full sun than in partial shade.
Periwinkle plants are tolerant of any type of well-drained garden soil but prefer a moist, organically rich loam. Adding some compost to your soil at planting can boost its organic content and improve its fertility, while adding fine sand to soil that tends to hold water for long periods can improve its drainage. Applying an annual application of balanced, 10-10-10 fertilizer in the spring is also helpful. Add granular fertilizer at a rate of 6 to 8 pounds per 1,000 square feet, or use water-soluble fertilizer, diluted at a rate of 1/4 teaspoon per gallon. Periwinkle stems can root when tips touch soil, and the plant has a tendency to be invasive. Its growth can be controlled by shearing plants back each year or by installing an in-ground barrier such as fencing to restrain the growth of a planting.