“Rue Elin” Is a vigorous, erect, clump-forming, rhizomatous, herbaceous perennial with pinnate, blue-green leaves and dark purple stems bearing large, loose, terminal panicles of fluffy, lavender flowers in midsummer. Flowers from May to July. Height 2.5m. Spread 1m. Grow in full sun or partial shade in a moist but well drained fertile soil.