Betonica macrantha aka Betonica Macrantha

Betonica macrantha, or big betony, is a herbaceous perennial. This means its soft growth dies back, then grows again. It belongs to the mint family, Lamiaceae. Its home range runs from northeastern Türkiye to northwestern Iran. It grows in temperate zones, where the climate is mild. It is not native to Britain or Ireland. Past names include Stachys macrantha and Stachys grandiflora. Garden sources also use the name Betonica grandiflora. Its leaves die back, so they do not stay green year-round.

The plant forms a bushy clump with upright growth. The clump spreads at a slow pace. The RHS gives a height of around 2 feet [0.6 metres]. Its full garden height range is 1.6–3.3 feet [0.5–1 metre]. Clumps can reach about 1.6 feet [0.5 metres] wide. They take two to five years to reach full size. The oblong leaves have neat teeth along their edges. Dense spikes of flowers rise above the leaves. Each pinkish-purple bloom has a hood and two lips. Each flower grows about 1.4 inches [3.5 centimetres] long.

Garden sources give different times for bloom. Missouri Botanical Garden gives May to June. Chicago Botanic Garden gives those same months. The RHS lists summer and early autumn instead. Bees and butterflies visit the blooms. Chicago also notes that the plant draws birds. The showy spikes suit beds, borders, and cottage gardens. Big betony works as an edge plant or groundcover, too. Sources suggest loose, informal groups and gardens for wildlife. They also suggest city courtyards as sites. The RHS lists gardens by the coast as well. It also suggests sites beneath roses or shrubs.

Choose full sun or part shade, with soil that drains well. The RHS calls for soil with a medium level of nutrients. It accepts chalk, loam, or sand. Acid, neutral, and alkaline soils all suit this plant. Keep soil moist but let excess water drain away. Missouri Botanical Garden rates its water needs as medium. Chicago says to water in the first year as roots settle. The plant grows in USDA zones 4–8. The RHS rates it H7, its top rating for cold hardiness.

Missouri Botanical Garden says the plant needs little care. Cut off old flower stems once blooms fade. Split clumps in spring to make more plants. Start seeds in a cold frame in spring or autumn. Slugs and snails may harm growth. Powdery mildew can occur, too. Missouri Botanical Garden reports no major pest or disease problems. Deer tend to leave the plant alone. Its roots cope with substances that black walnut roots give off. These substances can slow plant growth. The supplied sources give no advice on safe use as food. They do not say whether the plant is toxic.