Sasamorpha borealis

Sasamorpha borealis is an evergreen bamboo in the grass family, Poaceae. Its native range covers Korea, Sakhalin, and Japan. Japanese records include Hokkaido, Honshu, Kyushu, and Shikoku. It grows in a temperate climate. In Japan, it lives in woods and damp hollows. Older names include Sasa borealis and Arundinaria borealis. It is not native to Britain or Ireland.

This bamboo reaches about 10 feet [3 metres] in height. It keeps its leaves throughout the year. Its rhizomes run, though they spread at a gentle pace. This growth habit lets the clump extend beyond its starting point. Plants For A Future does not flag it as weedy. Growers may confuse it with Pseudosasa japonica. Its year-round leaves suit woodland gardens and shaded edges. Light tree cover provides the kind of shade it prefers.

Plant it in humus-rich loam with good moisture during growth. It accepts sandy soil and clay as well as loam. It tolerates mildly acid, neutral, and mildly alkaline soil. Partial shade suits it, including the light shade of open woodland. Plants For A Future lists USDA hardiness zones 6–9. That source also reports strong resistance to honey fungus. Its need for moist ground makes soil moisture a key growing concern.

Flowers appear only after gaps of many years. Each flower has both male and female organs. Wind carries the pollen. Seed production takes much of the plant's energy and weakens it. Some plants die after flowering, but others recover when left alone. Recovery can take years, during which plants may look poor. Plants For A Future warns against artificial NPK feeds at this stage. Such feeding can raise the risk of death. The seeds are edible when cooked and serve as a cereal. Their rare appearance limits their use as a food crop. The source lists no known hazards or medicinal uses.

Seed and division offer two ways to raise new plants. Sow fresh seed on the surface at about 20°C. Keep the compost moist while waiting for growth. Good seed may sprout soon, but germination can take three to six months. Grow seedlings in light greenhouse shade before planting them outside. They may need several years to reach planting size. Divide plants in late spring as new growth starts. Each division should retain at least three canes.