Helleborus Argutifolius
Formerly known as Helleborus corsicus, this is certainly the toughest hellebore, originating from the Mediterranean islands of Corsica and Sardinia. Large clusters of 20 or more apple-green cupped flowers are held over handsome foliage, appearing from mid-winter well into spring. Worth growing for the dramatic foliage alone, the margin of each leathery leaf is coarsely spined.
Hellebores are resilient garden plants and are best grown in the ground. Remove old foliage when new growth appears in autumn. Apply a mulch of well-rotted manure or quality compost at this time too. Watch for aphids and spray if necessary. Deadhead spend flowers to encourage increased flowering.