Eryngium alpinum 'Blue Star'

Common Name: eryngo 
Type: Herbaceous perennial
Family: Apiaceae
Zone: 2 to 8
Height: 1.00 to 2.50 feet
Spread: 1.00 to 2.50 feet
Bloom Time: July to August
Bloom Description: Metallic blue
Sun: Full sun
Water: Dry to medium
Maintenance: Low
Flower: Showy, Good Cut, Good Dried
Other: Thorns
Tolerate: Drought, Dry Soil

Culture

Easily grown in average, poor to moderately fertile, dry to medium, well-drained soils in full sun. Tolerates light shade, poor soils, drought and saline conditions. Intensity of blue flower/bract color is best in areas with full sun and cool nights. Tall plants tend to sprawl, particularly if grown in moist fertile soils or in anything less than full sun. Deadhead flowers after bloom to retain attractive plant appearance. This is a taprooted plant that transplants poorly and is best left undisturbed once established.

Noteworthy Characteristics

Eryngium alpinum, commonly called alpine sea holly, is a somewhat coarse, stiffly-branched, taprooted, rosette-forming herbaceous perennial that typically grows on upright stems to 25-32” tall with a spread to 18” wide. It is native to subalpine rocky areas and moist pastures up to 6500’ in elevation in central and southeastern Europe.

Strong, solitary, upright stems are topped from mid-summer into fall (July-early October) with single, cone-shaped, thistle-like, blue flower heads (to 2” long) densely packed with tiny blue flowers. Each flower head is subtended by a collar of 12-18 ornamentally attractive, bristly, finely-divided, somewhat soft-to-the-touch blue bracts which extend outward and upward from the base of the flower head. Plants feature ovate, spiny-toothed, heart-shaped basal leaves (to 3-6” long) and palmately-divided 3-lobed upper stem leaves. Foliage is green near the base of the plant, but upper leaves, upper stems, flowers and flower bracts are bluish.

Genus name comes from an ancient Greek name used by Theophrastus for a plant which grew in Greece (probably Eryngium campestre) or is a Greek reference to the prickly or spiny nature of plants in this genus.

Specific epithet means of mountains at altitudes usually above timberline.

‘Blue Star’ typically grows to 30-36” tall with a spread to 18” wide. Flower heads, bracts, stems and leaves are a more intense metallic blue than what is found on the straight species.

Problems

No serious insect or disease problems. Dislikes winter wetness and may benefit from a gravel mulch around the crown.

Garden Uses

Beds, borders, cottage gardens. Single specimen or small groupings of at least 3-6 plants or massed. Dryish, sun-baked beds. Excellent long-lasting cut flower that also dries well.