SEA HOLLY

FAMILY: Apiaceae | GENUS: ERYNGIUM

TYPE
  • Perennials
SUN EXPOSURE
  • Full Sun
WATER
  • Moderate Water
PLANTING ZONES
  • US (Upper South) / Zone 6
  • MS (Middle South) / Zone 7
  • LS (Lower South) / Zone 8

Plant Details

Most are erect, stiff-branched, thistlelike plants that bloom in summer, putting on a show of striking oval, steel-blue or amethyst flower heads surrounded by spiny blue bracts. They make long-lasting cut flowers and dry well for winter arrangements. Plants are sparsely clothed in deeply cut dark green leaves with spiny-toothed edges; upper leaves and stems are sometimes blue.

Another group of sea hollies has long, narrow, spiny-edged leaves that are quite similar to those of yucca. One of these, Eryngium yuccifolium, is native to the U.S.

Use sea hollies in borders or fringe areas, in deep, well-drained, sandy or gritty soils that are low in fertility. They are taprooted and difficult to divide, so propagate by root cuttings or by sowing seed in place (thin seedlings to 1 feet apart). Plants often self-sow. Resist deer.

alpine sea holly

eryngium alpinum

  • From southeastern Europe.
  • To 2 feet high, 1 feet wide, with steel-blue, 2 inches flower heads and large, deeply cut blue bracts.
  • Upper leaves and stems are tinged with soft blue to steel-blue.
  • Blue Star is a choice selection.

amethyst sea holly

eryngium amethystinum

  • From Italy and the Balkans.
  • To 2 feet tall, 1 feet wide.
  • Silvery blue stems; rich blue, inch-wide flower heads surrounded by silvery blue, 2 inches bracts.

miss will mott's ghost

eryngium giganteum

  • From the Caucasus and Iran.
  • Biennial to short-lived perennial.
  • To 34 feet or taller, 212 feet wide.
  • Oval or heart-shaped, medium green leaves to 6 inches long.
  • Three-lobed stem leaves.
  • In late summer, bears blue or pale green, conical flower heads surrounded by silvery, 2124 inches bracts; the plant dies after flowering ends.
  • Reseeds well.
  • Provide fertile soil, regular water.
  • Silver Ghost is shorter (2 feet.) with larger blooms.

false sea holly

eryngium planum

  • From southeastern Europe to central Asia.
  • To 3 feet high, 1 feet wide.
  • Leathery evergreen leaves; freely borne light blue flower heads to inches across, surrounded by narrow blue-green bracts.
  • Blue Glitter is a heavy producer of glittering, steel-blue flowers.

eryngium 'Saphhire Blue

  • One of the best sea hollies, with intense, steely blue flowers.
  • Upper leaves and stems also infused with blue.
  • Grows 2 feet high and 1 feet wide.

moroccan sea holly

eryngium variifolium

  • US, MS, LS, CS; USDA 6-9.
  • From Morocco.
  • Grows to 16 inches tall and 10 inches wide, with inch-wide, rounded, blue-gray flower heads and bluish white bracts.
  • Thistlelike evergreen leaves are heavily veined with white.

rattlesnake master

eryngium yuccifolium

  • US, MS, LS, CS; USDA 6-9.
  • Native to eastern and central U.S. Long (to 3 feet), narrow, spiny-edged leaves in a basal rosette to 2 feet wide.
  • Erect stems to 34 feet branch toward top and carry 1 inches-wide white owers without signicant bracts.

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