Vinca minor, commonly called lesser or dwarf periwinkle, myrtle, creeping myrtle or vinca covers the ground year-round with its evergreen foliage. It blooms in late spring and occasionally in summer and fall. Plant it on steep banks for erosion control, as a bedding plant or in planters and window boxes. It grows in U.S. Department of Agriculture plant hardiness zones 4 through 9. Each plant grows to only 3 to 6 inches tall but spreads to 6 to 18 inches wide.
Spacing on Slopes
Space lesser periwinkle plants 6 to 12 inches apart on slopes or steep banks to eliminate erosion and the need for dangerous mowing. The plants will completely cover the area in one year when planted 6 inches apart. When planted 12 inches apart, the area should be covered by the end of the second year.
Lesser periwinkle is considered an invasive species in many parts of the U.S. If you live where it is invasive, do not plant it and choose another ground cover.
Spacing in Landscapes
Plant lesser periwinkle 12 to 18 inches apart in flower beds and foundation plantings or around trees and shrubs. Planting it among spring-blooming bulbs provides an attractive, glossy green backdrop and additional floral interest. When you space plants 12 inches apart, they should cover the area within two years. When planted 18 inches apart, the plants will take longer to cover the ground or may not ever completely cover it. Plant annuals in between the lesser periwinkle plants for interest until they fill in.
Lesser periwinkle is a good fire-wise plant for areas where the risk of wildfire is high.
Spacing in Containers
Plant multiple lesser periwinkle plants 6 inches apart in rectangular window boxes or one plant per 6-inch container. The window box or container must have drain holes in the bottom to allow excess water to drain away. Use houseplant potting soil and check the soil often for dryness. The soil will dry out much more quickly in containers or window boxes than it does in the garden.
Lesser periwinkle is toxic if eaten, so choose another plant if you have curious children or pets.
Planting and Transplanting
Plant or transplant lesser periwinkle whenever the ground can be worked. Early spring is best. Summer planting requires more watering to keep the soil from drying out while the new plants become established. Partial shade, full sun or full shade are fine. Plant it in partial shade for deeper green leaves or in full sun for more flowers. It grows best in fast-draining soil that is rich in organic matter, although it will grow in most soil types.
Before planting, mix a 2- to 3-inch layer of aged cow manure, sphagnum peat moss, compost or composted shredded bark mulch into the top 8 to 10 inches of soil to increase organic matter and improve drainage.
Dig the planting holes just deep enough for the base of the plant stems to be at the same depth in the soil as they were growing previously. Spread a 2- to 3-inch layer of mulch over the soil to reduce moisture loss and weeds but keep it 1 to 2 inches away from the stems. Water the plants when the top of the soil begins to dry.
Do not plant lesser periwinkle in naturalized areas along streams and waterways where there is a high risk for wildfires.
Dividing for New Plants
Divide lesser periwinkle in early spring or fall every five years or so. New plants form where the stems touch the soil. If the area is mulched, this is less likely to happen. Water the plants a day or two before dividing. Use sterilized hand pruners to cut the connecting stems 1/4 inch below a set of leaves. Soak the pruners in household disinfectant for a few minutes then rinse them off. Push a shovel into the soil a few inches away from the new periwinkle plant all the way around it to loosen the soil then lift the plant up with the tip of the shovel. Plant in a new spot right away.