Alpine sea holly

Eryngium alpinum

Alpine European sea holly with the largest and most spectacular flower heads of any Eryngium — domed steel-blue thimbles surrounded by elaborate finely cut feathery blue bracts.

Hardiness ratings

Alpine sea holly hardiness across the four zone systems
SystemRatingTemperature rangeHow to read it
USDA hardiness zone Zone 4–8 −34.4 °C to −6.7 °C Plant tolerates down to this zone
RHS hardiness rating H7 down to −20 °C Plant needs at least this level of cold tolerance
Canadian plant hardiness zone Zone 4–8 −29 °C to −1 °C Plant tolerates down to this zone
Australian (ANBG) zone Zone 1–5 −15 °C to 10 °C Plant tolerates down to this zone

Growing notes

  • Plant in cool sunny borders — the showiest Eryngium for ornamental display, often described as the most beautiful flower of the European Alps
  • Tolerates richer moister soils than most sea hollies — does not demand sharp drainage
  • Distinct from other sea hollies in the database — alpinum has uniquely soft feathery bract collars
  • Excellent cut and dried flower

Categories

Related plants

Cross-check Alpine sea holly against your zones

Reference

Alpine sea holly on Wikipedia