Eryngium horridum (Sea Holly) — Clump-forming, upright and branching; some form basal rosettes

Overview

Eryngium horridum is a clump-forming, upright and branching; some form basal rosettes perennial in the genus Eryngium, part of the Apiaceae family, with deciduous or evergreen; leathery, often spiny, sometimes marbled or silver-veined foliage. Eryngium horridum grows best in full sun, and tolerates most soils and neutral to alkaline pH. Its UK hardiness is rated H4-H7. Suggested uses include gravel gardens, rockeries, coastal gardens, drought-tolerant borders and architectural planting.. It is native to Southwestern Europe and particularly coastal regions of Spain and Portugal..

About

Eryngium horridum is a perennial sea holly with leathery, often spiny foliage and an upright, clump-forming habit. Plants produce branching stems or basal rosettes and the leaves are sometimes marbled or silver-veined. It is native to the coastal regions of southwestern Europe, notably Spain and Portugal. Flowering occurs from June to September.

About the genus

Eryngium is a genus of flowering plants in the family Apiaceae. There are about 250 species. The genus has a cosmopolitan distribution, with centres of diversity in the western Mediterranean, South America and Mexico.

Wikipedia contributors, "Eryngium", CC BY-SA 4.0 — Eryngium

In the garden

Eryngium horridum is a clump-forming perennial in the Apiaceae family from the coastal areas of southwestern Europe, particularly Spain and Portugal. It carries leathery, often spiny leaves that may be deciduous or evergreen and can show marbling or silver veining; the habit ranges from upright branching stems to plants with basal rosettes. Flowering season runs June to September. Grow it in full sun on sharply drained soils such as sand, chalk or gravel; neutral to alkaline pH suits it best. Winter wet is fatal, so choose a south- or west-facing, exposed position and avoid heavy, moisture-retaining soils. Hardiness is given as H4–H7 (H4 average; H5 hardy; H6 very hardy; H7 fully hardy), so it tolerates anything from average UK conditions to the coldest garden situations when planted where drainage and exposure are right. Use Eryngium horridum in gravel gardens, rockeries, coastal borders and drought-tolerant or architectural schemes where its spiny leaves provide structure. Plant on slopes, in raised gravel beds or in rings of grit to ensure rapid drainage and reduce winter moisture. The upright, sometimes silver-veined foliage and branching habit hold form through the summer flowering period, making it a useful structural plant in exposed, low-nutrient sites.

Growing conditions

Best soil and position for Eryngium

Sunlight: Full sun
Soil type: Poor to moderately fertile, sharply drained sand, chalk or gravel
Soil pH: Neutral to alkaline
Soil moisture: Well drained to dry; winter wet is fatal
Aspect: South or west facing
Exposure: Exposed
UK hardiness: H4-H7

Plant details

Eryngium horridum size, habit and characteristics

Plant type: Perennial
Habit: Clump-forming, upright and branching; some form basal rosettes
Foliage: Deciduous or evergreen; leathery, often spiny, sometimes marbled or silver-veined
Suggested uses: Gravel gardens, rockeries, coastal gardens, drought-tolerant borders, architectural planting.
Native to: Southwestern Europe, particularly coastal regions of Spain and Portugal.

Care notes

Pruning and caring for Eryngium horridum

Cultivation: Give them the hottest, poorest, best-drained position in the garden. Rich soil produces soft growth that flops and rots, so resist feeding. Most resent disturbance because of a long taproot, which is also what makes them genuinely drought-tolerant once settled - plant young and leave alone. Excellent in gravel gardens and on thin chalk.
Pruning: Cut spent stems back in early spring rather than autumn, since the dried heads are among the best winter silhouettes in the border.
Propagation: Sow seed fresh in autumn, as germination becomes erratic once stored. Root cuttings taken in winter are the reliable route for cultivars; division rarely succeeds given the taproot.
Pest resistance: Slugs damage young growth, particularly on the rosette-forming species; otherwise little troubled.
Disease resistance: Healthy where drainage is adequate. Root and crown rot follow winter waterlogging, which is by far the commonest cause of loss.

Frequently asked questions

How do I grow Eryngium horridum?

Give them the hottest, poorest, best-drained position in the garden. Rich soil produces soft growth that flops and rots, so resist feeding. Most resent disturbance because of a long taproot, which is also what makes them genuinely drought-tolerant once settled - plant young and leave alone. Excellent in gravel gardens and on thin chalk.

Where is the best place to plant Eryngium horridum?

Eryngium horridum prefers full sun. It suits exposed positions.

What soil does Eryngium horridum need?

Eryngium horridum is adaptable and grows happily in most soil types, including poor to moderately fertile, sharply drained sand and chalk or gravel. It prefers neutral to alkaline soil. Aim for soil that stays well drained to dry; winter wet is fatal.

How do I prune Eryngium horridum?

Cut spent stems back in early spring rather than autumn, since the dried heads are among the best winter silhouettes in the border.

Is Eryngium horridum hardy in the UK?

Eryngium horridum has an RHS hardiness rating of H4, meaning it is hardy through an average UK winter, tolerating -10 to -5°C.

How do I propagate Eryngium horridum?

Sow seed fresh in autumn, as germination becomes erratic once stored. Root cuttings taken in winter are the reliable route for cultivars; division rarely succeeds given the taproot.

More in the Eryngium genus

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