Eryngium alpinum 'Superbum' is an elegant species for the herbaceous border, with large amethyst-blue flowers and metallic stems, it is one of the showiest of all the Sea Hollies.
The amethyst-blue flowers are cupped by three strokeable rows of feathery bracts which surround a 5cm (2in) long thimble. They flowers mature to an intense steel blue/purple in summer and autumn and the upper leaves also acquire the same amethyst-blue tint.
Eryngium alpinum is native to the alpine pastures of Switzerland and the plants are extremely hardy and long-lived. This fascinating architectural plant grows to around 60cm (24in) tall and is at its peak during July and August. It is a tough plant for full sun in well drained, light soils and will tolerate light shade. Each individual floret is rich in nectar so the prickly flowers are popular with bees.
With a long season of interest the plants add texture and colour to the garden and the blooms and foliage are perfect for cutting. They add interest to the winter garden and are lovely when dried.
The blossoms are actually soft-to-the-touch and are often sold as a cut flower. Once cut they harden and make a long-lasting dried flower. To dry for indoor arrangements, cut before the flowers are fully open.
Sowing: Sow October to February or March to September
The seeds may need a period of cold to enable them to germinate.
Sea holly has very long roots that penetrate deeply in the soil and are often several feet long. The plant should be placed in its final position whilst small since it resents root disturbance.
Sowing October to February.
Sow in John Innes seed compost or something similar, cover with a thin layer of compost. After watering place the seed container in an unheated greenhouse or coldframe.
Germination is irregular, between 5 and 90 days. As each seed germinates transplant into its own pot containing gritty compost to grow on, until large and strong enough to be planted outdoors into its final position in the garden.
Sowing March to September.
During the warmer months, you can “imitate the winter” by using the following method of stratification:
Sow in John Innes seed compost or something similar, place each container in a polythene bag and put into the refrigerator (not the freezer compartment) for 2 to 3 weeks. (Fridges are the deal temperature at around 4°C (39°F)
After this time place the containers outside in a cold frame or plunge them up to the rims in a shady part of the garden border and cover with glass or clear plastic. As each seed germinates transplant into its own pot containing gritty compost to grow on, until large and strong enough to be planted outdoors into its final position in the garden.
Eryngiums key requirement is that gardening oxymoron - moisture-retentive soil and good drainage. This equates to rich alluvial or humus-rich soil that holds moisture without getting waterlogged in winter.
Divide mature plant in early spring or autumn, take care since the plant resents root disturbance.
Although you can cut back flower stems after flowering, the seedheads are a very attractive feature so are usually left over winter. Tidy dead and decaying foliage in early spring to discourage rot.
Plant Uses: Costal or Gravel Gardens. Cottage/Informal Gardens, Flower Arranging, Borders and Beds, Wildlife Gardens Attractive to Bees and Butterflies.
Beloved of flower arrangers for their striking foliage and flower heads.
To use the blooms for dried flower arrangements, cut the flowers before they are fully open. Simply cut with a knife or secateurs. The difficulty is deciding when the stem is ready for cutting. In general, the flowers on the stem should be turning an appropriate blue colour. This process can take up to 10 days from the time it is first noticed. Avoid the temptation to cut back all the flower-heads in autumn as they provide interest in the winter garden.
Eryngium is a genus in the family Apiaceae of about 230 species of annuals and perennials with hairless and usually spiny leaves, and dome-shaped umbels of flowers resembling those of thistles.
The genus has a cosmopolitan distribution, with the centre of diversity in South America. Some species are native to rocky and coastal areas, but the majority are grassland plants, their prickly leaves are a defence to deter grazing animals.
Eryngium alpinum is native to Austria, Liechtenstein, Croatia, France, Switzerland, Italy, and Slovenia. It grows in subalpine scrub, rocky areas and wet pastures, preferably in limestone, at an altitude of 1,500 to 2,000 metres (4,900 to 6,600 ft) above sea level.
Eryngium is derived from the Greek word hruggion, a name given by Theophrastus for 'a spiny leaved plant'.
The species name alpinum refers to its native habitat, the alpine pastures. This species is commonly known as the Alpine Sea Holly or with the title of Queen of the Alps.
Common names of the genus include Sea-holly and Eryngo, the former typically being applied to coastal species, and the latter to grassland species. Eryngium are often referred to as Sea Hollies, despite its name and appearance, this is unrelated to the more familiar holly and is in fact an umbellifer: one of that large and confusing family which includes the parsleys, carrots and parsnips.
- Additional Information
Average Seed Count 25 Seeds Family Apiaceae Genus Eryngium Species alpinum Cultivar Superbum Common Name Alpine Sea Holly, Queen of the Alps Other Common Names Blue Sea Holly Other Language Names FR: Panicaut alpinum, Panicaut des Alpes, Etoile des Alpes. Hardiness Hardy Perennial Hardy Hardy to minus 10°C (14°F) Flowers Steel Blue, July to September Foliage Glaucous in summer Height 60-90cm (24-30in) Spread 45cm (18in) Position Full Sun Aspect All aspects, exposed or sheltered Soil Well-drained/light, Moist, Sandy