What: Eryngium agavifolium, the agave-leaf sea holly, is a distinctive foliage perennial for the Northwest. Since agaves do not like our cold and wet winters, with a little imagination this can serve as a good substitute. The architectural quality of the flat, semi-evergreen rosette adds interest to the sun garden. Each glossy dark-green leaf is about 16 to 24 inches long, sword-shaped with a sharply toothed edge. In late summer it puts up a 4-to-5 foot flower stem bearing a spiny group of 2-inch, greenish-white, thimble-shaped blooms. As the season progresses the flowers mature to a dark chocolate-brown and last until mid-winter. Eryngium agavifolium is quite attractive to bees and butterflies and is also deer resistant.
Where: Plant in full sin to light shade. This plant looks good with other sun and drought loving perennials such as Salvia greggii, Acanthus mollis, shrub roses, verbascum, blue oat grass and hebes.
Size: Grows to 4 feet tall by 4 feet wide in 10 years.
Care: This sea holly grows best in well-drained and sandy soil in full sun to light shade. Once established it is very drought tolerant. This tough perennial is relatively short-lived, but will reseed into the garden. Spare seedlings are easily removed or relocated as young plants. Remove the flower stems when they are no long attractive and older yellow and brown foliage can be pulled free from the evergreen rosette in late fall and winter.