The rosy red flower spikes of Red Valerian bloom for an extended period in early to mid-summer. This plant prefers sterile, limey soils and does well in rock gardens and walls. Freely self-seeds in optimum growing conditions, to prevent self-seeding and to encourage additional bloom, remove spent flower stems. Centranthus ruber var. coccineus is more compact in size and has darker red flowers than the straight species. An old-fashioned, easy perennial.