Eryngium planum, commonly called sea holly, produces small steel-blue flower heads surrounded by pointed bracts. This summer-flowering perennial grows approximately 80 cm tall and adds texture to borders and fresh or dried arrangements. Each package contains three bare roots for planting.

Plant in spring when the ground has thawed, in full sun and well-drained soil. A relatively light soil suits it well; avoid rich, persistently wet sites. Set the roots approximately 2.5 cm deep and allow about 45 cm between plants. Water after planting to help them establish.

Combine the flowers with ornamental grasses and pink or yellow perennials in naturalistic gardens. Once established, the plant tolerates dry spells, but excess moisture can cause root rot. Wear gloves when handling the pointed bracts, and remove spent flowers if you want to limit self-seeding.