Spike your interest with Éryngiums

Loved for their sculptural shapes and cool colour palette, sea hollies will give gardens a border boost from late summer into autumn

- Louise Curley

WITH their distinctive flowerheads made up of spiky collars of bracts surrounding central, thistle-like clusters of tightly packed, tiny blooms, eryngiums are one of the most sculptural of garden plants. Emerging in midsummer, the flowerheads continue to provide interest right through autumn and into winter, as they fade from blue or silver to buff and brown tones, and they look particularly good when their jagged outlines sparkle with frost.

Packed with nectar, the flowers are a magnet for bees and butterflies. They’re also good for cutting, and if the stems are picked just as the flowers are starting to open they can be dried to use as Christmas decorations – spray them gold or silver for a lovely effect.

Worldwide, there are more than 240 species of eryngium, with the ones most commonly grown in British gardens originating from Europe. The common name sea holly covers all eryngiums, but it only truly applies to our native E. maritimum. It grows on beaches along the south coast, where it thrives in a nutrient-poor, free-draining environment with lots of sunshine. Those worth growing in the garden don’t require such extreme conditions, but they are averse to sitting in damp, heavy soil – European eryngiums are very hardy, but winter wet will kill them.

More tender types 

Less commonly grown in UK gardens are eryngiums that are native to South America, where they thrive in damp, grassy areas. These are not as hardy – they cannot cope with anything below -5°C, so are only suitable for growing in fairly mild locations in the UK. They need a moisture-retentive soil that will not become waterlogged in winter and they like a fertile soil.