Agapanthus praecox aka Common Agapanthus

Agapanthus praecox is an evergreen perennial in the amaryllis family. Gardeners know it as African blue lily or African lily. It comes from southern South Africa, including the Cape region. Its native range reaches southwest KwaZulu-Natal. It grows on stony slopes in rocky grassland. This plant forms leafy clumps from underground rhizomes. It grows at a moderate pace.

Garden clumps reach about 2.7 feet [0.8 metres] in height. Flower stems rise to about 5 feet [1.5 metres]. Plants spread about 2–3.3 feet [0.6–1 metre]. Glossy green leaves grow in a rosette at the base. Each strap-shaped leaf measures 1–2 feet [0.3–0.6 metres] long. The leaves have smooth edges and no hairs. Their arching shape contrasts with the upright flower stems. These thick green stems are round, smooth, and hollow.

Blue or white flowers open from summer into autumn. The main display comes in mid to late summer. Each stem carries a rounded umbel at its tip. Flower heads span about 0.4 feet [0.125 metres]. Each tubular flower has six petal-like parts. A darker line runs down the centre of each part. Bees and butterflies visit the flowers for nectar. The plant also draws hummingbirds, and its flowers suit cutting. Long capsules with three sides hold many seeds.

Give this plant full sun for the best flower display. It prefers rich, moist soil that drains well. Sandy soil and loam both suit it. It accepts acid, neutral, or alkaline soil. Water needs rise during growth; keep it drier in winter. Established plants can withstand drought. RHS rates it H2, so protect it from frost. NC State lists USDA zones 8b–11b. Move pots to a frost-free place in cold areas. Plants reach mature size in two to five years. Divide clumps to raise more plants. Remove dead leaves and old flower heads; little pruning is needed.

Use it in borders, groups, coastal gardens, or patio pots. It also suits slopes, courtyard gardens, and wildlife gardens. It has become a weed in parts of Australia. Slugs, snails, and agapanthus gall midge can cause damage. Other pests include aphids, scale insects, mites, and mealybugs. Diseases include root rot, Botrytis rot, powdery mildew, and viruses. Verticillium wilt and Macrophoma can also affect plants. All parts are harmful if eaten. Sap can irritate skin and eyes, while ingestion can injure the mouth. Reports note local medicinal use, but this does not establish safety.