About
Eryngium amethystinum, the amethyst sea holly, is an upright, branching perennial to around 60 cm with deeply cut, spiny, mid-green leaves and small, cylindrical, steel-blue or violet flowerheads surrounded by long, narrow, metallic-blue bracts in summer. Excellent for cutting and drying.
About the genus
Eryngium, the sea hollies, are biennials and perennials with spiny-margined, often architectural leaves and distinctive, dome-shaped flowerheads surrounded by spiny bracts, often in metallic shades of blue, silver or purple. Drought-tolerant and ornamental, they are grown in sunny, well-drained borders.
Growing conditions
SunlightFull sun
Soil typeChalk, Loam, Sand
Soil pHAcid, Alkaline, Neutral
Soil moistureWell-drained
AspectSouth-facing, West-facing, East-facing
ExposureExposed
UK hardinessH5
Plant details
Plant typeHerbaceous Perennial
HabitClump forming
FoliageDeciduous
Height0.1-0.5 metres
Spread0.1-0.5 metres
Time to full height2-5 years
Suggested usesRock garden, City and courtyard gardens, Coastal, Cottage and informal garden, Gravel garden
Native toPyrenees to Morocco
Care notes
CultivationGrow in dry, well-drained soil that is poor to moderately fertile. Full sun is essential as is protection from winter wet
PruningAlthough you can cut back flower stems after flowering the seedheads are a very attractive feature so are usually left over winter
PropagationPropagate by root cuttings in late winter
Pest resistanceMay be susceptible to leaf and bud eelworms, and slugs and snails
Disease resistanceMay be susceptible to root rot and powdery mildews