How to grow eryngiums

Where to grow eryngiums

Eryngiums need plenty of sunshine and free-draining soil. They can tolerate poor soil, and a spot at the foot of a wall is a good position as the soil will remain dry over winter. It’s also a good idea to plant eryngiums away from the edge of a border or path, as their spikes can be quite sharp. They work well in gravel gardens and don’t need a lot of watering.

How to plant eryngiums

Dig a generous hole, larger than the pot your sea holly came in and add a handful of grit to boost drainage. Follow our step by step guide to planting perennials.

Caring for eryngiums

In colder climates you may need to protect the roots with a mulch of straw over winter, and tidy spent foliage in spring to prevent rot.

Propagating eryngiums

Species eryngiums can be grown from seed, although if you have a named cultivar, take root cuttings to ensure it stays true to type. Follow our step-by-step guide to taking root cuttings. Some eryngiums can be propagated by division in spring. Watch Sarah Raven demonstrate how to divide herbaceous perennials.

Eryngiums: problem solving

Eryngiums are generally trouble-free plants with no pests or diseases, though slugs and snails can slowly eat small parts of the tough foliage.

Eryngiums to grow

• Eryngium varifolium – a compact sea holly, with small spiky flowers on sturdy, upright stems from July to September
• ‘Neptune’s Gold’ – a colourful plant. The spiky bracts are silvery blue at the base, turning gold at the tips. The stems of 'Neptune's Gold' are blue, and the foliage yellow
• 'Big Blue' – as the name suggests, the flower cones are large and a very intense blue. They appear from June to August and contrast beautifully with the grey-green in leaves
• 'Picos Blue' – a more intense blue than the species bourgatii, and slightly larger
• Eryngium x tripartitum – with branching violet stems emerging from a rosette of leaves, the flowers are smaller and appear more starry, as the dark blue bracts are more like narrow daisy petals rather than lacy ruffs
• Eryngium Yuccifolum - somewhat reminiscent of yuccas, hence its scientific name
• 'Jos Eijking' - a striking hybrid sea holly with electric blue, long-lasting flowers
• 'Blue Hobbit' - a compact cultivar with small, steely blue flowerheads. It’s perfect for growing at the front of a herbaceous border, gravel garden or in a container, and makes a wonderful cut flower
• 'Jade Frost' - a relatively small sea holly with green, cream-edged leaves and flowerheads that start out off-white before turning a rich indigo tone
• 'Blaukappe' - a tall-growing cultivar with small, electric-blue flowerheads