Eryngium x tripartitum (Tripartite Sea Holly) is an upright perennial with a basal rosette of coarsely toothed, gray-green leaves. From mid-summer to early fall, wiry, violet-blue branching stems bear cone-shaped, thistle-like, metallic-blue flower heads. Each flower head is surrounded by a ruff of slender, spiny, dark blue bracts. Attractive to bees and butterflies but deer resistant, this striking Sea Holly is good for cutting as well as the border.
- Recipient of the prestigious Award of Garden Merit of the Royal Horticultural Society.
- Grows in clumps of stiffly erect, branched stems up to 3-4 ft. tall (90-120 cm) and 20 in. wide (50 cm)
- Performs best in full sun in fairly dry, poor to moderately fertile well-drained soils. Tolerates light shade, poor soils, drought and salt.
- Excellent choice for gravel gardens, cottage gardens and coastal gardens. May be planted as a single specimen or in groupings. Perfect for cut or dried flower arrangements too!
- Although you can cut back flower stems after flowering the seedheads are a very attractive feature so are usually left over winter
- Watch for leaf and bud eelworms, powdery mildew and root rot.
- Propagate by root cuttings in late winter