True blue

Sea holly adds architectural structure to borders for months and provides bees with nectar, says Hazel Sillver, as she describes the best varieties to plant now

- Hazel Sillver

RESEMBLING sophisticated thistles, sea hollies (eryngiums) have cone flowerheads surrounded by a starry collar of barbed bracts. Sometimes the whole plant glows a mesmerising shade of violet-blue or seems to shimmer like metal in the sun. The spiky, coarse appearance and architectural structure of sea hollies lends them to contemporary naturalistic plantings of perennials and their love of drainage makes them ideal for gravel gardens.

Rich supply of nectar

As well as the popular blue forms, there are lesser-known eryngiums with ivory, silver and claret blooms, and some boast lush blade-like foliage. “Eryngiums are stunningly beautiful, and far more varied than most gardeners realise,” say Brian and Kathy Pike, who hold the UK National Collection of Eryngiums in North Yorkshire. “Despite their reputation for needing full sun and poor soil, you can find one that will thrive in pretty much any spot, and they fit equally well into formal gardens, cottage gardens or urban courtyards.”

Sea hollies are a must-have in wildlife gardens, since they provide a rich supply of nectar for pollinators. Bee expert and author Dave Goulson deems them stellar plants for bees and rates Eryngium planum ‘Blaukappe’ as one of the best at attracting them. For cut or dried flowers, E. alpinum is superb and surprisingly soft to the touch. And for creating layers in the border, the airy E. x tripartitum has a useful ‘see-through’ quality.

Sun worshippers