Cirsium japonicum aka Tiger Thistle

Cirsium japonicum is known as Japanese thistle or no-azami. It belongs to the daisy family, Asteraceae. Its native range spans China, Vietnam, and temperate eastern Asia. Records include Japan, Korea, Taiwan, and parts of eastern Russia. In Japan, it grows on sunny lowland and foothill slopes. It is not native to Britain or Ireland.

This plant forms clumps and has a short life. It can grow as a biennial or short-lived perennial. The RHS gives a garden height of 4.9–8.2 feet [1.5–2.5 metres]. Its descriptive account places it near 6.6 feet [2 metres]. Clumps spread about 1.6–3.3 feet [0.5–1 metre]. Plants reach their mature size within one or two years. The dark green leaves have spines and deep lobes. Some leaves divide further into a pinnate shape. The plant sheds its leaves rather than keeping them year-round.

Tall stems branch above the clump and carry thistle-like flower heads. The flowers have narrow, tube-shaped parts in pink or lilac-purple. Bloom runs from late summer into early autumn. The RHS suggests this species for wildflower meadows and wildlife gardens. It can also grow in planted beds. Its height and branching stems give it a tall garden form. Gardeners can raise new plants from seed. Remove spent flower heads when seed is not needed.

For cultivation, choose full sun and moist soil with good drainage. The plant also tolerates partial shade and a range of soils. Suitable soils include clay, loam, sand, and chalk. It accepts acid, neutral, and alkaline conditions. Both exposed and sheltered sites suit it. The RHS rates its cold tolerance as H7. This rating covers temperatures below −4°F [−20°C] under UK conditions. Plants For A Future lists USDA zones 5–9. The RHS reports few pest problems, though powdery mildew may occur. Plants For A Future flags some weed potential.

Plants For A Future records cooked leaves and young roots as food. It singles out spring leaves for eating. The same source reports no known hazards. That report does not establish safety for pets or every use. It also records traditional medicinal uses for roots, leaves, and stems. These include uses linked to bleeding, inflammation, and urine flow. Such records describe past use, not proof of safe treatment.