perennial

Alpine Sea Holly

Eryngium alpinum

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Alpine Sea Holly (Eryngium alpinum) at Sargent's Gardens

Alpine Sea Holly flowers

Alpine Sea Holly flowers

(Photo courtesy of NetPS Plant Finder)

Height:  32 inches

Spacing:  15 inches

Sunlight:  full sun 

Hardiness Zone:  2b

Ornamental Features

Alpine Sea Holly features bold steel blue ball-shaped flowers with silvery blue bracts at the ends of the stems from early to mid summer. The flowers are excellent for cutting. Its attractive spiny lobed leaves emerge steel blue in spring, turning silvery blue in color throughout the season. The fruit is not ornamentally significant. The navy blue stems are very colorful and add to the overall interest of the plant.

Landscape Attributes

Alpine Sea Holly is an herbaceous perennial with a mounded form. Its relatively fine texture sets it apart from other garden plants with less refined foliage.

This plant will require occasional maintenance and upkeep, and is best cleaned up in early spring before it resumes active growth for the season. It is a good choice for attracting butterflies to your yard. Gardeners should be aware of the following characteristic(s) that may warrant special consideration;

  • Self-Seeding

Alpine Sea Holly is recommended for the following landscape applications;

  • Mass Planting
  • General Garden Use
  • Container Planting

Planting & Growing

Alpine Sea Holly will grow to be about 32 inches tall at maturity, with a spread of 18 inches. When grown in masses or used as a bedding plant, individual plants should be spaced approximately 15 inches apart. It grows at a fast rate, and under ideal conditions can be expected to live for approximately 3 years.

This plant should only be grown in full sunlight. It prefers dry to average moisture levels with very well-drained soil, and will often die in standing water. It is considered to be drought-tolerant, and thus makes an ideal choice for a low-water garden or xeriscape application. It is particular about its soil conditions, with a strong preference for poor, alkaline soils, and is able to handle environmental salt. It is highly tolerant of urban pollution and will even thrive in inner city environments. This species is not originally from North America.

Alpine Sea Holly is a fine choice for the garden, but it is also a good selection for planting in outdoor pots and containers. Because of its height, it is often used as a 'thriller' in the 'spiller-thriller-filler' container combination; plant it near the center of the pot, surrounded by smaller plants and those that spill over the edges. Note that when growing plants in outdoor containers and baskets, they may require more frequent waterings than they would in the yard or garden. Be aware that in our climate, most plants cannot be expected to survive the winter if left in containers outdoors, and this plant is no exception. Contact our store for more information on how to protect it over the winter months.

 
 
Hardiness Zone Plant Height Minimum Sunlight Soil pH Preference
Characteristics
Massing  Garden  Container 
Applications
Flowers  Foliage Color  Texture  Bark  Attracts Wildlife 
Ornamental Features