Berberis calliantha

Berberis calliantha, or black-berried barberry, belongs to the barberry family, Berberidaceae. It comes from the Tsangpo Gorge in southeastern Tibet. It grows in mountain regions within a temperate climate. This species is a shrub, not a tree. It is not native to Britain or Ireland. Its evergreen leaves give it a lasting presence in gardens.

The shrub grows upright and forms a bushy shape. In gardens, it reaches about 3.3–4.9 feet [1–1.5 metres] tall. Its spread is about 1.6–3.3 feet [0.5–1 metre]. It takes five to ten years to reach full size. The shoots bear spines, and the dark green leaves resemble holly. Soft yellow flowers open in spring. Blue-black berries follow in autumn, adding a second season of interest.

Grow it in moist soil that drains well. It accepts chalk, clay, loam and sand. Acid, neutral and alkaline soils all suit it. Full sun gives the best leaf colour, though it tolerates partial shade. PFAF also places it at woodland edges and in dappled shade. The RHS lists both sheltered and exposed sites as suitable. Its UK hardiness rating is H7, covering temperatures below −4°F [−20°C]. PFAF gives a USDA hardiness range of zones 6–9.

Its size suits beds, borders, courtyards and smaller garden spaces. The RHS also suggests coastal gardens, pots, hedges and screens. It can fit both cottage gardens and less formal planting. Prune after the flowers fade to keep its shape. For a stronger foliage display, cut it back hard in spring. Semi-hardwood cuttings provide a way to raise more plants. Aphids and berberis sawfly may attack it. Powdery mildew is another possible problem. PFAF does not flag the species as a weed.

The sources disagree about whether people should eat the fruit. PFAF lists the berries as edible, either raw or cooked. It describes their taste as sour and reports no known hazards. The RHS instead warns against eating the ornamental fruit. Its warning covers both people and pets. The RHS also advises gloves and other protection when handling this shrub. These conflicting reports do not establish that the berries are safe to eat.