Eryngium tripartitum

Eryngium tripartitum or the Tripartite Sea Holly is a beautiful medium-sized perennial with splendid semi-evergreen silver-green foliage, consisting of lobed, dentate basal leaves. From July to September, it continuously blooms with its countless small conical heads that are a remarkable bluish-violet colour. A magnificent blue thistle, to be planted in the sun, in poor, sandy or rocky, very well-drained soil, and to be handled with caution or gloves.

Eryngium tripartitum or Tripartite eryngo, more commonly known as Sea Holly, is native to the Mediterranean region and belongs to the Apiaceae family. This herbaceous perennial with a taproot measures 60 to 90 cm (24 to 35in) tall with a width of 50 cm (20in), forms a compact and bushy, spreading clump with semi-evergreen foliage. It has a rosette of lobed, dentate, oval, and glossy basal leaves, initially green, then silver-grey, and finally becoming silver-green in autumn. Its sturdy, highly-branched, upright and erect stems are a splendid blue-green. From July to September, they bear numerous flower heads that are initially blue, then violet in summer, and finally violet-blue in autumn. Its flowers measure 3.5 cm (1in) long and are cone-shaped, surrounded by narrow bracts, 2 to 4 cm (1 to 2in) long, and blue-grey to dark blue. Its flowers attract many pollinating insects.

This blue thistle appreciates the sun and poor, sandy, and rocky, well-drained soils. Particularly decorative due to its compact bushy habit, its very long, uninterrupted, bluish-violet flowering and its splendid spiny grey-blue foliage, this Sea Holly will be the perfect companion for plants in poor and dry soils, such as Grasses, Wormwoods, Lavenders, Agapanthus, and Garden Irises. However, it is advisable to plant it in the background of flower beds to avoid getting too close to its prickles! This Blue Thistle is one of the best plants for creating splendid dried bouquets. Simply cut the stems before the flowers fully open and hang them upside down to dry.

This Eryngium tripartitum was awarded the Royal Horticultural Society's Award of Garden Merit in 1993.