Ceratostigma plumbaginoides aka Blue Leadwood

Ceratostigma plumbaginoides is a low perennial called blue leadwort or plumbago. It belongs to the thrift family, Plumbaginaceae. It comes from north-central and eastern China. Wild plants grow in rocky sites and near foothills. Thin stems rise from rhizomes and form a spreading mat. Garden plants stand about 0.5–1 foot [0.15–0.3 metres] tall. RHS gives a broader height range, reaching 1.6 feet [0.5 metres]. Their spread can reach about 1.6 feet [0.5 metres]. Roots can carry the plant beyond its first patch.

The leaves are simple, glossy, and oval, with smooth edges. They grow in an alternate pattern along the stems. New growth may have a burgundy tint. Green summer leaves turn bronze, red, or purple in autumn. The plant drops its leaves for winter. Fresh shoots appear late in spring. This late start makes it useful among spring bulbs. Avoid digging or raking its patch before shoots appear. Slender stems may branch and have fine bristles near their tips.

Blue flowers grow in small groups at the stem tips. Each flower has five petals that form a star. They rise above the leaves from summer into autumn. Missouri Botanical Garden lists July to September as the bloom season. Other sources report flowers lasting until frost. Violet-tinged buds open from deep red calyces. Fall leaf colour can overlap with the last flowers. Butterflies and hummingbirds visit the blooms. Pale yellow-brown capsules hold red-brown seeds.

Grow it in sun or partial shade, not full shade. Afternoon shade helps in places with hot summers. It accepts clay, loam, sand, and a broad pH range. Soil must drain well; wet ground does not suit it. Sources support dry to moist soil and medium watering. It grows fast and needs little routine care. USDA zones 5–9 and RHS rating H5 cover its hardiness. Winter survival can be less sure in zone 5. A light winter mulch helps protect plants there.

Use it beneath shrubs, along edges, or in rock gardens. It also trails over container edges and helps hold banks. Watch its spread where it could crowd nearby plants. Deer tend to leave it alone. Powdery mildew and citrus mealybugs can occur. RHS also notes rare cases of honey fungus. PFAF lists no known food or medicinal uses. NCSU warns that skin contact can cause dermatitis in some people.