How to prune eryngium giganteum 'silver ghost'

Remove dead plants after seed has scattered in late summer or autumn. Allow seed heads to ripen fully and drop. Then pull or cut the dead plant at the base. Leave some seed heads on the soil surface to aid germination of the next generation.

Once, after the plant has set seed and died. Eryngium giganteum 'Silver Ghost' is monocarpic — it flowers once, sets seed, then dies. Do not deadhead if you want it to self-seed and naturalise in the garden. Remove spent plants entirely after seed set. Self-sown seedlings will flower in subsequent years; there is no repeat pruning routine.

Allow seed heads to ripen fully and drop. Then pull or cut the dead plant at the base. Leave some seed heads on the soil surface to aid germination of the next generation.