Astilbe thunbergii aka Thunberg's Astilbe

Astilbe thunbergii is a perennial in the saxifrage family. It comes from Japan and grows in a temperate climate. Kew lists its range in central and southern Honshu and Shikoku. Plants For A Future gives a wider Japanese range. That account also includes Hokkaido and Kyushu. It records the plant on sunny, grassy slopes. The species is not native to Britain or Ireland.

Plants For A Future describes a rounded plant with moderate growth. It reaches about 1.6 feet [0.5 metres] in height. Its foliage adds interest to planted beds and borders. The same source lists pink flowers but gives conflicting bloom times. One entry says May; another places flowering in midsummer. Each flower has both male and female organs. Insects pollinate the flowers. These records do not establish one clear flowering season for gardens.

Grow this plant in rich soil that holds moisture through summer. Plants For A Future recommends moist or wet, peaty ground. It accepts sandy soil, loam, and clay. Its stated preferred pH range is 5.5 to 7. The source also lists tolerance of mildly alkaline soil. Partial shade is its preferred garden setting. It can also grow in full sun, matching its recorded wild habitat. Reliable soil moisture remains a key part of its care. Plants For A Future lists it as hardy to UK zone 7. That rating does not establish an RHS H-category.

Use it in borders, containers, or groups in woodland gardens. Its rounded form and foliage suit these uses. Plants For A Future recommends spring division to keep plants vigorous. Divide established plants every three to four years. Large pieces can go straight into their garden sites. Grow smaller pieces in pots under cold-frame cover first. Wait until they show strong growth before planting them out. The source also suggests spring seed sowing under glass. It notes that this seed method lacks species-specific detail.

Plants For A Future reports that young leaves are edible when cooked. The leaves can also serve as a tea substitute. Its food-use rating is low, at one out of five. The source lists no known hazards and no known medicinal uses. This does not amount to a full safety assessment for pets. It records no weed potential for the species.