Lavender-blue flowers peeking out from evergreen leaves on low, trailing stems are the decorative features of periwinkle (Vinca minor). A perennial plant in U.S. Department of Agriculture plant hardiness zones 4 through 9, periwinkle is also called vinca, creeping myrtle, common periwinkle and lesser periwinkle. In some areas of the United States, periwinkle is invasive. Deer usually avoid this plant.
Periwinkle is a useful plant in gardens with challenging growing conditions. Tolerating deep shade, dry soil, shallow, rocky soil, erosion and drought, periwinkle grows where many plants struggle to survive.
Grow periwinkle as a ground-cover plant in shady areas, such as under trees, and on slopes and banks, where it controls soil erosion. Another option for using periwinkle as a ground cover is in bulb beds, where its loose habit allows bulb shoots to poke upward. Periwinkle also grows well in containers with bottom drainage holes and in sunny spots indoors and outdoors.
Periwinkle is so vigorous that it can grow out of control and swamp other plants. Reduce periwinkle's spread by pruning it to the desired size at least once per year with pruning shears. Before and after pruning, wipe the pruning shear blades with a cloth soaked with rubbing alcohol to prevent the spread of plant diseases.
Good growing conditions for periwinkle include organically rich, freely draining soil and sunny or partially shaded spots. This plant grows in full shade and almost any soil. For the fastest growth and most flowers, grow periwinkle in sunny spots and moist soil.
Cultivars of periwinkle offer different flower and leaf colors from the species plant. Periwinkle ‘Bowles’ Variety’ (Vinca minor ‘Bowles’ Variety’) features deep-blue flowers on deep-green foliage. Hardy in USDA zones 3 through 9, ‘Bowles’ Variety’ attracts butterflies and hummingbirds but is disliked by rabbits and deer. This cultivar grows 4 to 6 inches tall and 18 to 23 inches wide.
Periwinkle 'Honeydew' (Vinca minor 'Honeydew') is named for its yellow-green leaves, which provide a contrast to its 1-inch-wide, lavender-blue flowers. 'Honeydew' forms dense mounds up to 6 inches tall. It is hardy in USDA zones 4 through 8.
Periwinkle is poisonous to some animals and to humans. Cats and dogs become ill from eating periwinkle. Symptoms of poisoning include tremors, seizures, lack of coordination and depression. In severe cases, eating periwinkle can cause coma and death in cats and dogs.
If eaten, periwinkle causes stomach upsets in people.