Learn How To Plant, Care, and Grow Spectacular Sea Holly (Eryngium)

Attractive, Sea Holly plants (Eryngium) are striking ornamental perennials grown for their arresting, thistle-like, silvery, or blue-tinted flower heads adorned with a ruff of showy bracts. Blooming in summer and sometimes into fall, they are useful in rock gardens, coastal gardens, and borders, where their steel blue flowers and foliage complement the vibrantly colored summer flowers. Their beautiful texture, unique color, long-lasting flowering, and remarkable qualities as cut flowers make them a favorite of florists, gardeners, bees, and butterflies. They are exceptionally carefree plants if they are given a well-chosen site. Here are some basic rules that need to be followed to enjoy their splendid flowers.

1. Select The Right Site

• Eryngium prefers full sun – at least 6 hours of direct sunlight per day.
• Eryngium prefers dry, poor to moderately fertile, well-drained soils except for Eryngium pandanifolium (Giant Sea Holly), which prefers moist soils.
• Good drainage is critical, or your plant will die off from root rot.
• Most Sea Holly species are reliably perennial in Hardiness Zones 4 – 9. Exceptionally hardy, Eryngium alpinum is perennial in Zone 2. Eryngium amethystinum and Eryngium yuccifolium are perennial in Zones 3. Not sure about your growing zone? Check here.
• Eryngium needs winter protection and a warm site to allow the rosettes to overwinter successfully. Otherwise, these plants use up all their energy replacing foliage.
• Eryngium is a tap rooted plant that transplants poorly and is best left undisturbed once established. Select your site carefully!