Eryngium thrives in full sun, ideally six hours or more daily. It may flower poorly and become leggy in shade.

It prefers well-drained, poor to moderately fertile soil like sandy or chalky types. Avoid heavy, waterlogged soil to prevent root rot.

Water thoroughly after planting, then sparingly. Eryngium is drought-tolerant once established and dislikes overwatering.

Very little feeding is needed. Too much fertiliser can cause floppy growth and fewer flowers. A light spring mulch or feed is optional.

Deadhead faded flowers to encourage longer blooming or leave seedheads for winter interest. Cut back to ground level in early spring.

Plant in spring or autumn in well-prepared, free-draining soil. For bare-root plants, soak roots before planting and ensure the crown is level with the soil.

Propagate by seed or cuttings. Division is possible but slow to recover. Seeds may need cold stratification before germination.

Most varieties are fully hardy in the UK but dislike wet winters. Good drainage or winter protection is advisable.

Flowers typically appear from July to September. Plants grow between 60cm and 1m tall, with striking metallic blue to purple spiky blooms.