|This rhizomatous or tuberous evergreen or semi-evergreen perennial is grown primarily as a low maintenance ground cover. It is best when used in large sweeping masses rather than spotty, individual clumps. Produces dense spikes of vivid violet-blue flowers in early fall to late fall. Both drought and shade tolerant, this versitile plant can grow in full sun or moist sites just as easily. It does however, prefer acid soil. Excellent on slopes or at the base of trees where roots will not permit grass to grow. To maintain an attractive appearance, cut back tops each February before new growth begins.