Eryngium zabelii Big Blue

The Eryngium x zabelii 'Big Blue' is a magnificent variety of sea holly, undoubtedly one of the most beautiful ornamental thistles. It develops sturdy silver-blue-gray stems that proudly bear conical gray-violet inflorescences crowned with finely cut spiny bracts of relentless steel blue. It is a plant with well-armored foliage, but also a focal point for perennial borders . It blooms in July, and its flowers, which remain decorative for several weeks, are as ornamental in borders as they are in fresh or dried bouquets. A thistle that thrives in the sun, in well-drained soil, even when dry in summer.

The 'Big Blue' Sea Holly is a hybrid plant, belonging to the Apiaceae family (formerly Umbelliferae), obtained by cross-breeding Eryngium alpinum and Eryngium bourgatii. This variety is considered by professionals to be one of the most decorative blue thistles. The plant, anchored on a large taproot, forms a clump of heart-shaped basal leaves, which are deciduous to semi-evergreen, spiny and leathery, deeply incised, silver-veined greenish-gray. The floral stems rise to 75 or 85 cm (30 or 34in) from the ground and the vegetation spreads over a diameter of 40 to 50 cm (16 to 20in). In July-August, the conical flower heads, borne at the top of the stems with small green leaves, are initially gray and then violet and steel blue. They measure 8 to 13 cm (3 to 5in) in height and 5 cm (2in) in diameter, and are topped with a collar of narrow blue bracts measuring 6 cm (2in) in length. The cone consists of tiny flowers that will not produce viable seeds.

The Eryngium zabelii 'Big Blue' thrives in deep, dry, well-drained soil, even poor and rocky in hot and sunny positions. This superb perennial adds an interesting texture to borders, thanks to its somewhat intesnse but original and graphic habit. Plant it in rockeries and borders in a dry garden alongside shrubby salvias, Perovskia, Pennisetums, Stipa, Gaura lindheimeri 'Snowstorm', Verbascum bombyciferum 'Polarsommer', and Salvia nemorosa 'Caradonna'. The fresh or dried flowers of Eryngium are widely used in bouquets.