The spiky, bluish-gray-looking plants offer the charm of an unusual contrast, mingled with the soft, wispy foliage of other plants. Their large leathery and thorny leaves with steel reflections bring a strong presence. However, this offensive appearance does not always reflect their nature, like the cardoons which make a velvet paw when brushed against.
Pictured is Eryngium x zabelii ‘Big Blue’
1- Spectacular foliage, velvet paws
In a dry and sunny garden, few perennials with large foliage resist these conditions except the artichoke ( Cynara scolymus ) and the cardoon ( C. cardunculus ). They both form towering clumps of cut, metallic foliage up to 2 m high. A profusion of flower heads with mauve flowers stand out above the foliage during the summer. Despite their appearance, the leaves are very soft to the touch.
To enhance the shine of silver foliage, combine it with other gray foliage and white blooms.
- Plant the cardoons behind a border of purple sages such as Salvia pratensis or sclarea ,
- in a white clump with Crambe cordifolia , mullein ( Verbascum sp.)
- a white cistus ( Cistus florentinus …),
- sagebrush like Artemisa ‘Powis Castle’…,
- by Gauras lindheimeri ,
- Create a border of bear’s ear ( Stachys byzantina ) or Convolvulus cneorum , a silver-leaved ground cover bindweed.
2- Blooms with a persistent metallic shine
Panicauts or blue thistles ( Eryngium ) are biennial or perennial plants remarkable for their bluish or silvery cylindrical umbels, surrounded by a spiny collar. The flowers persist a good part of the summer and their silhouette is preserved until winter.
Eryngium alpinum ‘Blue Star’ is one of the most beautiful species of the genus. Its heart-shaped, spiny, bright green basal leaves are topped with a bouquet of 70 cm high inflorescences. The steel blue, finely cut collars frame the large cylindrical flower heads in July-August.
- Eryngium bourgatii , smaller (H: 50 cm) offers light blue flowers, framed by long silvery bracts in July-August. The leathery, deeply divided leaves are veined with white.
- E. planum has small oval leaves. From June to September, it raises very branched stems 1 m high, with small radiant blue flowers.
Eryngium alpinum ‘Blue Star’
How to plant and multiply Eryngium?
You will find plants in the perennial section of garden centres.
Ornamental thistles appreciate deep, well-drained soils and a warm, sunny position.
- Sowing is done as soon as the seeds ripen at the end of summer.
- Hybrids are propagated by root cuttings that you place under a frame in sand during the winter.
Plant the panicauts at the bottom of the bed in the company of grasses and yellow flowers ( Anthemis, Helianthus, Solidago …) to create a vibrant scene. Be sure to control seed spread.
3- Azure ball games with ball thistles
Much less thorny than Eryngium , E chinops are perennials 1 m or more, with dark green to gray cut foliage. Nicknamed “ball thistles”, they are also part of the artichoke family (Asteraceae). Their cloud of blue spherical flower heads seem to hover above a network of slender stems, from June to September.
Echinops bannaticus (H: 1.20 to 1.50 m) have inflorescences 3 to 6 cm in diameter . ‘Taplow Blue’, renowned for its floridity, and ‘Blue Globe’ are an intense dark blue.
- Echinops ritro ‘Veitch Blue’ (H: 1m) features smaller balls with an equally vibrant colour, blooming again in the fall.
- Echinops sphaerocephalus forms large light gray spherical inflorescences. Its imposing tuft rises to more than 1.50 m.
How to plant and multiply them?
- Plant the Echinops in well-drained soil, not too rich and in the sun.
- Sow the seeds in the spring or divide the clump.
- Cut back the clump at the beginning of winter.
Echinops also fits well in wild gardens in the company of grasses, cockroaches, etc. than to contemporary gardens for its graphic aspect. You can combine it with the pastel or white colors of lavatera, yarrow, mugwort as well as the brighter tones of euphorbia.
Text and photos: Eva Deuffic