True blue
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
