Thalictrum rochebruneanum aka Thalictrum Rochebruneanum

Thalictrum rochebruneanum is a perennial in the buttercup family, Ranunculaceae. Its common names include meadow rue and lavender mist meadow rue. It comes from central Japan and central Korea. This plant grows in temperate regions and forms upright clumps. Rhizomes help form the clump below ground. Its leaves fall away at the end of the season.

Garden height varies between the sources. RHS gives about 1.6–3.3 feet [0.5–1 metre]. Chicago Botanic Garden reports 4–5 feet [1.2–1.5 metres]. RHS lists a spread of 0.3–1.6 feet [0.1–0.5 metres]. The compound leaves have many small, finely divided leaflets. Their gray-green color gives the plant a soft look. The leaves add interest even before the flowers open. Plants take two to five years to reach full size.

Small flowers grow in loose sprays above the leaves. Their colors range from lavender-pink to white. Yellow stamens hang down from the flowers. The colored flower parts include sepals rather than true petals. Chicago lists the main bloom season as July through August. Its account also notes flowers in late June. The tall stems and open sprays suit the back of borders. Groups can bring both leaf texture and late-summer color. Other uses include meadow gardens, informal beds, and naturalized areas. Gardeners can also grow it for cut flowers.

Give this meadow rue moist soil rich in humus. RHS favors partial shade and a sheltered site. Chicago also lists full shade as suitable. The plant accepts chalk, clay, and loam soils. It grows in acid, neutral, or alkaline conditions. RHS lists both well-drained and poorly drained moist sites. Chicago gives USDA hardiness zones 4–7. RHS rates it H7 for cold tolerance. RHS says the stems may need support. Missouri Botanical Garden says sturdy flower stems usually stand without it.

Care needs are low, according to Missouri Botanical Garden. Cut the stems down after flowering ends. Divide plants in spring when new shoots appear. Seeds can go into pots in a cold frame. Sow them when ripe or in early spring. Serious pest and disease problems are not usual. Powdery mildew can develop when conditions turn dry. Rust may also occur from time to time. The plant resists browsing by deer and rabbits. RHS warns that touching the leaves may irritate skin. Wear gloves and other protective clothing when handling it.