Russian Sage. Perovskia atriplicifolia.

Tubular blue flowers are produced on tall stalks in mid to late summer. Prefers well drained soils in a sunny location. When cutting back in fall or early spring be sure to leave 15cm (6in) or so of wood at the base, or better yet, wait till new growth begins and cut just above the highest bud. A great filler for flower arrangements.