Vinca major aka Bigleaf Periwinkle

Vinca major, or greater periwinkle, is an evergreen perennial. It belongs to the dogbane family, Apocynaceae. Sources place its home across southern Europe and western Asia. This range includes southern France, Turkey, and the western Caucasus. It is not native to Britain or Ireland. Gardeners grow it for ground cover and in containers.

The plant makes a dense mat with long, trailing stems. These stems root where their nodes touch the soil. Flowering shoots stand upright, while other stems creep along the ground. Reported garden heights range from 0.25–1.6 feet [0.08–0.5 metres]. Several sources give 1–1.5 feet [0.3–0.46 metres]. Spread estimates range from 1–8.2 feet [0.3–2.5 metres]. Growth can extend beyond these limits as stems take root. The stems hold milky latex. Glossy, dark green leaves grow in opposite pairs. Their broad bases can have a heart shape. Fine hairs line the leaf edges.

Single violet-blue flowers grow where leaves join the upright stems. Each flower has five lobes around a central tube. The main bloom runs from April to May. Scattered flowers may follow through summer and into autumn. Slender fruits reach about 0.17 feet [0.05 metres] long. They split when dry, freeing three to five seeds. Garden plants seldom form these fruits.

Greater periwinkle prefers part shade and moist, rich soil. Good drainage helps, though RHS lists a broad drainage range. It also grows in sun and near-full shade. RHS reports that sun gives the best flowering. It accepts clay, loam, sand, and chalk across varied pH levels. Established plants resist drought, but very dry sites suit them poorly. Reliable US hardiness covers USDA zones 7–9. Oregon State also notes possible survival in zone 6. RHS rates its UK hardiness as H6. Its foliage covers soil beneath bulbs, roses, and shrubs. It can help hold soil on banks and slopes. Trailing stems suit walls, hanging baskets, and pots. People also use the stems for basket work.

Fast spread can make this plant hard to contain. It is invasive in several US states and can displace native plants. Water can carry stem pieces that start new colonies. Check local planting rules before using it outdoors. Aphids and nematodes may attack it. Disease risks include rust, root rot, leaf spot, and blight. It can host the bacterium linked to Pierce's disease in grapes. Deer tend to leave it alone. PFAF lists no edible uses and warns that large amounts are poisonous. That source records medicinal uses, which do not establish food safety.