Eryngium bourgatii aka Mediterranean Sea Holly

Eryngium bourgatii is known as Mediterranean sea holly or Mediterranean eryngo. It belongs to the Apiaceae family and is a herbaceous perennial. Its native range includes France, Spain and Morocco, including the Pyrenees. It forms clumps, with leaves gathered into a basal rosette. Stiff, branched stems rise above the leaves during the growing season. Garden plants reach about 1.5–2 feet [0.45–0.61 metres] tall. They spread about 1.5–2 feet [0.46–0.61 metres] wide. RHS gives a smaller upper spread of 1.6 feet [0.5 metres].

The leaves have deep lobes and pale, silver-white veins. Their green varies from gray-green to dark green. The plant loses its leaves at the end of the season. Vivid blue stems carry dense heads of tiny blue flowers. These rounded or cone-like heads look much like small thistles. Each head has a ring of narrow, spiny bracts beneath it. The bracts may look gray-green, silver-blue or violet. Flowers appear from July to September, sometimes lasting into early October. The seedheads can remain as a winter feature.

Give this plant full sun and soil that drains well. It grows in sandy, loamy or chalky soil. It accepts acid, neutral and alkaline conditions. Poor to moderately fertile soil suits it well. Once established, it copes with drought, dry soil and salt. Light shade is tolerated, though full sun gives better results. Cool nights and full sun help bring out blue tones. Rich, moist soil or shade can make taller stems sprawl. It is hardy in USDA zones 5–8 and rated H5 in Britain.

Sea holly suits beds, borders, rock gardens and gravel gardens. It also fits coastal sites and dry, sun-baked planting areas. Grow it alone, in small groups or in larger drifts. Its flower stems last well when cut and also dry well. Remove spent flowers for a tidier look, or keep seedheads through winter. Its taproot makes moving established plants difficult. Leave settled plants undisturbed where possible. Root cuttings taken in late winter offer a way to propagate it.

Care needs are low, and serious pest or disease trouble is uncommon. Slugs, snails, and leaf and bud eelworms may still attack. Root rot and powdery mildew are possible problems. Wet soil in winter is a concern. Gravel around the crown may help protect it from winter damp.