Eryngium (Sea Holly): The Steel-Blue Accent for Bouquets

Eryngium, or sea holly, looks prickly: steel-blue heads framed by a ruff of sharp bracts. It is often mistaken for a thistle, but it is actually related to carrots and dill. In bouquets sea holly adds a cool shimmer and a wild texture, and when dried it keeps its colour for months. Here is what types exist, how to grow them and how florists use them.

What Is Eryngium

Sea holly (Eryngium) is a large genus in the carrot family with more than two hundred species across Europe, Asia, Africa and the Americas. Most are drought-tolerant perennials with tough, spiny leaves and dense heads of tiny flowers surrounded by a star of bracts. In many species not only the flower heads but also the upper stems and bracts turn blue, which gives the plant its metallic sheen.

Sea Holly Species

• Flat sea holly (E. planum) — common in Ukrainian steppes and meadows, with small bluish heads on branching stems.
• Sea holly (E. maritimum) — a glaucous plant of sandy Black Sea and Azov coasts; it is rare, so do not pick it in the wild.
• Alpine sea holly (E. alpinum) — with large, soft, lacy ruffs; one of the most beautiful for gardens.
• Giant sea holly (E. giganteum) — a silvery-white biennial that self-seeds.
• Cut-flower varieties — hybrids with intensely blue heads grown especially for floristry.

Sea Holly in Bouquets

Eryngium is a natural, undyed blue, which makes it valuable for cool palettes. It goes with white and cream roses, lisianthus, eucalyptus, craspedia and solidago in yellow-and-blue designs, as well as in bouquets for men and buttonholes. It lasts 10–14 days in a vase. More cool-toned flowers are in blue flowers.

How to Grow Sea Holly

Sea holly needs sun and poor, dry, free-draining soil; in rich, moist ground it flops and loses colour. Sow seed in late autumn or in spring after cold stratification. It has a taproot and resents transplanting, so plant young seedlings straight into their final position. Care is minimal: water only in drought and skip the fertiliser.

How to Dry Eryngium

Cut the stems once the heads have turned fully blue, tie them in bunches and hang them upside down in a dark, airy place. In 1–2 weeks the sea holly will be dry, keeping its shape and most of its colour, ready for dried bouquets alongside statice.

FAQ

Is sea holly a thistle?

No, although it looks like one. Sea holly belongs to the carrot family, while thistles are in the daisy family.

How long does eryngium last in a vase?

10–14 days, after which you can dry it.

Is sea holly prickly?

The bracts are stiff and sharp, so handle it carefully; cut-flower varieties are softer.

Where should I plant sea holly?

In sun and poor, dry soil without standing water — a gravel garden or rockery is ideal.

Author: Maria Svitlovir

Graduated from Taras Shevchenko National University of Kyiv, Institute of Biology and Medicine (2001). BSc in Biology, MSc in Horticulture. Writes about plants, works at a garden centre selecting and repotting plants, and contributes to plant reference guides.

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