Family: Apiaceae
Common Name: Sea Holly

This large genus of annuals, biennials and herbaceous or evergreen perennials originates mainly from Europe and South America. They are grown for their unusual, spiny flower heads which mostly have a blueish, metallic lustre. Dried, they keep their colour and are used for winter arrangements. Sea holly has been used in folk medicine since antiquity. It has also been used as a vegetable and a flavoring agent.

Species

E. agavifolium zone 7, from Arg­entina, is a tall, clump-forming perennial, to 1.5 m (5 ft), with narrow, spiny, green leaves and pale green-white flowers.

The species E. amethystinum, zone 7, growing to 75 cm (30 in), has shiny, deep blue upper stems and deep blue flower heads in late summer.

E. mar­itimum, zone 5, sea holly, from Europe, is a much-branched perennial, having silver-green, basal leaves and pale blue flowers from the summer through to the autumn. It grows to 30 cm (12 in).

E. planum, zone 4, grows to over 1 m (3 ft), with branching, blue stems and small, metallic blue flower heads.

Cultivation

Eryngiums make good border plants, preferring a light, sandy soil, though they will grow in most soils provided they are well drained. They need full sun. E. mariti­mum is useful for seaside gardens but the soil must be deeply dug as it has long, thong-like roots. Propagate from seed in late spring or from root cuttings in winter. Seed should be sown where it is to grow as it does not transplant well.

Climate

There are species suited to various climatic zones.