{"id":10540,"date":"2022-05-24T00:00:00","date_gmt":"2022-05-23T22:00:00","guid":{"rendered":"https:\/\/c01.purpledshub.com\/gardensillustrated\/?post_type=purple_issue&p=10540"},"modified":"2022-05-25T10:58:19","modified_gmt":"2022-05-25T08:58:19","slug":"plant-profile-eryngium","status":"publish","type":"post","link":"https:\/\/c01.purpledshub.com\/gardensillustrated\/2022\/05\/24\/plant-profile-eryngium\/","title":{"rendered":"Plant profile: Eryngium"},"content":{"rendered":"\n

Eryngium<\/em><\/h2>\n\n

As varied in form as they are widespread, sea hollies lend instant character to a planting scheme with their sculptural bearing and shimmering colour<\/p>\n\n

WORDS DAN PEARSON | PHOTOGRAPHS JASON INGRAM<\/p>\n\n

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Eryngium alpinum<\/strong><\/em>
The largest-flowered form, this queen-of-the-alps has a ruff of metallic-blue flowers. Grows in sub-alpine scrub and rocky areas in Europe, but prefers deep, well-drained soil in a garden setting. 90cm x 30cm. RHS H5, USDA 2a-8b\u2020. <\/figcaption><\/figure>\n\n
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PLANT PROFILE<\/h5>\n\n\n\n

What <\/strong>A diverse range of thistle-like perennials. Though not all are armoured, most have an architectural appearance.<\/p>\n\n\n\n

Origins <\/strong>Some grow in the sand dunes of northern Europe, others in dry, rocky areas of the Mediterranean and the Near East. E. <\/em>yuccifolium <\/em>lives in mid-western USA, and most evergreen species originate in South and Central America.<\/p>\n\n\n\n

Season <\/strong>Late spring to late summer.<\/p>\n\n\n\n

Size <\/strong>Ranging in size from a modest 30cm to a domineering 3m.<\/p>\n\n\n\n

Conditions <\/strong>Given sunshine, an open aspect and free drainage, eryngiums are a hardy and long-lived genus.<\/p>\n\n\n\n

Hardiness <\/strong>Mainly RHS H5, USDA 3a-8b.<\/p>\n<\/div><\/section>\n\n

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Eryngium eburneum <\/strong>
<\/em>Native to Brazil and Argentina, with evergreen basal rosettes of reflexed foliage reminiscent of a puya. Finely spoked flower spikes hold clusters of small, white thimble-like heads free of the foliage, which mounds to 40cm x 40cm (flower spikes to 1m). RHS H4. <\/figcaption><\/figure><\/div>\n\n

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Eryngium maritimum
<\/em><\/strong>Native to coastlines in northern Europe, most commonly found in sand dunes. Needs perfect drainage and a lack of competition in the border. Metallic-blue thistles and aluminium-coloured foliage. Gently self-seeds. 50cm x 30cm. RHS H5.<\/figcaption><\/figure><\/div>\n\n
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Eryngium agavifolium<\/strong>
<\/em>Evergreen basal rosettes of laurel green with barbed margins that are deceptively soft to the touch. Tall flower spikes with greenish-white flowers that blacken in autumn. Long-lived and gently self-seeding. 1.5m x 60cm. RHS H4.<\/figcaption><\/figure><\/div>\n\n

Eryngiums are an adaptable and distinctive tribe of perennials with as much subtlety at one end of the spectrum as drama at the other. I first became aware of them in the mid 1970s through the renowned plantswoman Beth Chatto, who was using sea hollies on her stand at the RHS Chelsea Flower Show. I had seen our native Eryngium <\/em>maritimum <\/em>with its galvanised foliage and electric-blue thistles growing in sand dunes on the south coast, but Beth teamed it with drought-loving perennials and grasses to demonstrate its garden-worthiness. She introduced me to many more forms through her book The <\/em>Dry <\/em>Garden <\/em>and through her plantings in her gardens in Colchester, Essex, notably in the Gravel Garden, with its spectacular display of drought-tolerant plants. Later, when travelling in the mountains of northern Spain, I saw for myself E. <\/em>variifolium, <\/em>with its armoury of thorns and silvery midribs, and the imposing, intense blue E. <\/em>bourgatii <\/em>\u2018Picos Blue\u2019, basking in sunshine on the tussocky scree.<\/p>\n\n

Eryngiums have been part of an informal palette in British gardening for longer than one might imagine, used for their ability to conjure a wild place without feeling remotely like an interloper. The horticulturist and writer William Robinson wrote vividly about them in his book <\/span>The Wild Garden, <\/em>published in 1870, while the great plantswoman Ellen Willmott was well known for surreptitiously distributing seed of biennial Eryngium giganteum <\/em>whenever she visited a garden. Miss Willmott\u2019s ghost, as it became known, takes easily to a place it likes and these \u2018wild\u2019 introductions soon had their influence on a generally more formal Victorian horticulture.<\/p>\n\n

Today, in these more informal times, eryngiums have become an established part of the perennial palette. Appearing at the height of summer, their distinctive form and metallic sheen team well with grasses and naturalistic perennials such as Verbena macdougalii <\/em>\u2018Lavender Spires\u2019 and Oenothera lindheimeri <\/em>(formerly Gaura lindheimeri). <\/em>Flowering over a considerable period in summer, their compound, thimble-shaped flowers are magnets to pollinating insects. A plant such as E. <\/em>x zabelii <\/em>\u2018Big Blue\u2019 also has considerable impact in terms of colour \u2013 blue in almost all its parts and entirely otherworldly. Eryngiums have a long season, extending the nectar-producing period into late summer, and as they go over many hold their skeletal forms well into the winter to further extend their duration of interest.<\/p>\n\n

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Eryngium bourgatii <\/em>\u2018Picos Blue\u2019 <\/strong>
A Mediterranean sea holly from Spain and the Pyrenees, found in rubbly ground. Heavily veined, thistly rosettes of foliage, and deep-blue, metallic flowers and stems intensified by dry growing conditions. 60cm x 30cm. AGM*. RHS H5.<\/figcaption><\/figure><\/div>\n\n
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Eryngium yuccifolium<\/em><\/strong>
Long-lived and clump forming, native to the grass prairies of central and eastern USA. The soft, bluegreen, tapered leaves resemble those of a yucca. Best left undisturbed as it develops a deep taproot. 80cm x 40cm. RHS H4, USDA 3a-8b.<\/figcaption><\/figure><\/div>\n\n
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Eryngium pandanifolium<\/em> \u2018Physic Purple\u2019<\/strong>
Prefers damp soil in warmer countries, but must not lie wet in winter if it is to avoid frost damage in cooler climates. Cut leaves to the ground every few years to reduce a build-up of old foliage. 2.5m x 1m. RHS H4.<\/figcaption><\/figure><\/div>\n\n

Given sunshine and free drainage, the majority of eryngiums are reliably perennial. The deciduous forms retreat back to a tight rosette in winter which, in the first part of summer, quickly in British gardening, used for their ability to conjure a wild place <\/span>H4. expands to provide great visual interest prior to flowering: marbled and laced with silver in the case of E. variifolium, <\/em>or jaggedly architectural in plants such as E. agavifolium. <\/em>The brilliant laurel-green of the early rosettes of this species is arguably one of its best moments, but this Argentinian has power in its root and sends up a rapid bolt of vertical growth that suspends the greenish-white flowers clear in their own air space.<\/p>\n\n

Several of the herbaceous species retain an airiness in their flowering panicles. E. ebracteatum, <\/em>for example, has myriad tiny thimbles that are so delicate you might at first think it was a sanguisorba. E. eburneum, <\/em>meanwhile, is distinctive for the pale, silvery-white thimbles that are held rigorously on branched, arching stems, as if mapping a constellation.<\/p>\n\n

The sculptural nature of eryngiums is amplified in some of the evergreen species, with architectural foliage that can be relied upon year-round and impressive spires of summer flowers. The E. pandanifolium <\/em>I grow in my Somerset garden Hillside is one around which you have to build a planting. It was given to me by the botanist James Compton, who collected it in Uruguay (although he tells me it grows more widely) where it was growing en masse on the banks of a stream. It is the exception to the rule in terms of growing conditions, as it loves damp feet and good living. Its viciously barbed, sword-like leaves erupt in a great rosette that, in high summer, sends stems of tiny, dark flowers soaring to as much as three metres in the air.<\/span><\/p>\n\n

With glittering flowerheads that light up the garden and complement other colours so well, it\u2019s easy to see how these care-free plants have become stalwarts of the summer border. And with the trend towards drier, hotter summers, they are destined to grace our gardens for years to come. <\/p>\n\n

Dan Pearson is a writer and award-winning garden designer. <\/em>danpearsonstudio.com<\/a> <\/strong><\/p>\n\n