Mostly spiny-leafed, rosette-forming plants that produce erect, thistlelike, leafy stalks bearing tight, silvery or blue-tinted flower heads surrounded by showy bracts. Bloom in summer (sometimes into fall). Upper leaves, leafstalks, bracts, and flowers may all be frosted with silver or tinted in shades of blue or amethyst.
Sea hollies from dry, rocky areas in Europe, North Africa, Turkey, central Asia, China, and Korea tend to be taprooted; they prefer dry well-drained, poor to moderately rich soils; need protection from excessive winter water. Those from wet grasslands in Mexico, Brazil, and Argentina have fibrous root systems and prefer moist, well-drained soils. Taprooted forms are difficult to divide but may be propagated by root cuttings. If seeding, sow in place. Some species reseed vigorously. Watch out for snails and slugs.
Useful in rock gardens and for long displays in borders. Good choice for dried arrangements.Eryngium amethystinum
From Italy and the Balkans. To 2 1/2 ft. high and 1 1/2 ft. wide, with taproot. Spiny, medium green leaves to 6 in. long. Silvery blue stems and conical, 1-in. amethyst flower heads surrounded by 2-in., silvery blue bracts.
Compact, uniform plant grows to about 10 in. tall and 12 in. wide and is loaded with large flowers. Ea...
Grows to 1 ft. tall and 6 ft. wide, with curved branches that radiate in all directions. Shorter needl...
Mediterranean native to 2 1/2 ft. tall and 1/2 ft. wide. Bears so-called everlasting flowers, with dai...