Eryngium alpinum

alpine sea holly

Outstanding Qualities

Of the many species in this genus, Eryngium alpinum in particular resembles a thistle, although it is definitely not such a villain, yet has all the distinctive architectural qualities in shape and size. The flowers are almost like an Elizabethan ruff, or collar, with their feather-like, multiple spiny bracts radiating around 1.5 inch tall, cylindrical umbels that are steel-blue or white in color. The glossy, somewhat heart-shaped, basal leaves form a rosette and they have serrated edges. Other attributes include being attractive to bees and butterflies as well as drought tolerance and not tasty to deer. The blooms appear in mid-to-late summer and stay attractive as they age well into autumn. Plus they are a long-lasting cut flower that also dries well. Eryngium alpinum mixes well in the garden with peonies and grasses, especially blue oat grass.

Colors & Combos

Great Color Contrasts: gold, dark green, black

Great Color Partners: blue, silver, purple

Culture Notes

This sea holly grows best in well-drained and sandy soil with full sun. Once established it is very drought tolerant. This tough perennial is relatively long lived and resents being disturbed and is difficult to transplant due to its long tap root. Make sure it does not get crowded by its neighbors. Remove the flower stems when they are no long attractive and cut back the foliage once it has yellowed in fall.

© - Ettore Balocchi

Quick Facts

Plant Type: perennial

Foliage Type: semi-evergreen

Plant Height: 2 ft. 4 in. (0.70 m.)

Plant Width/Spread: 1 ft. 4 in. (0.40 m.)

Hardiness: USDA Zones 5 to 8

Flower Color: blue

Sun/Light Exposure: full sun

Water Requirements: drought tolerant when established