Eryngium - Giant Blue Sea Holly (Eryngium Giganteum) Giant Ornamental Blue Thistle Flower

Eryngium - Giant Blue Sea Holly (Eryngium Giganteum) Giant Ornamental Blue Thistle Flower

Perennial

Height 3 ft

This variety of Eryngium giganteum is a species of flowering plant in the family Apiaceae, and is a short-lived herbaceous perennial thistle native to the Caucasus and Iran in Western Asia. 

Eryngium giganteum, is a large, strikingly ornamental and architectural plant with coarse, thistle-like, clump-forming biennial or short-lived perennial that typically grows 2-4 ft tall (less frequently to 6 ft). Plants feature basal rosettes of heart-shaped green leaves (to 6 in long) and smaller spiny ovate stem leaves.

Tiny, stemless, blue silver flowers tightly packed into cone-shaped, thistle-like heads (umbels to 4 in long) appear in late spring, in branched clusters on stiff stems that rise from the centres of the basal rosettes. Each flower head displays a showy collar of spiny, holly-like, silvery grey bracts (each bract to 2.5 in long).

• Full sun
• Loamy sandy well draining soil
• Surface sow onto moist well-drained seed compost. Just cover with potting mix. Propagate 18-22°C. for 2 to 4 weeks. Do not exclude light. Germination can be slow. Seal seed container in a polythene bag and leave for 2 further weeks, then cold stratify. Move to a fridge 4°C for 3 to 6 weeks. After this return to warmth but no more than 18°C. If germination does not occur within 6 to 10 weeks, return to fridge for further 3 to 6 weeks. Examine regularly and immediately remove any seeds which show signs of germination. Move to 8cm pots. Acclimatize and transplant out when large enough and all risk of frost has passed.
• OR direct sow outdoors in early spring or late fall - or place seeds in the fridge for three weeks (a cold treatment is required to sprout well). Cover lightly and water in lightly.
• Plant spacing: 24 in apart
• Germination: 60 days after chill period.
• Seed Count: 10