Sea holly

Eryngium maritimum

Coastal native perennial with steely-blue spiny leaves and architectural blue thistle-like flower heads. A signature plant of British shingle beaches.

Hardiness ratings

Sea holly hardiness across the four zone systems
SystemRatingTemperature rangeHow to read it
USDA hardiness zone Zone 5–9 −28.9 °C to −1.1 °C Plant tolerates down to this zone
RHS hardiness rating H6 −20 °C to −15 °C Plant needs at least this level of cold tolerance
Canadian plant hardiness zone Zone 5–8 −23 °C to −1 °C Plant tolerates down to this zone
Australian (ANBG) zone Zone 2–6 −10 °C to 15 °C Plant tolerates down to this zone

Growing notes

  • Outstanding forage for bees and solitary wasps
  • Architectural seed heads persist through winter and feed seed-eating birds
  • Drought tolerant and salt tolerant — perfect for coastal and gravel gardens
  • Long taproot — does not transplant well, sow in place or use young plants

Categories

Related plants

Cross-check Sea holly against your zones

Reference

Sea holly on Wikipedia