Reading Rob's comment about Melianthus major smelling of peanut butter has got me…
They prefer fertile, well-drained soils, which grow in partial-shade with ample water.
You can propagate from seed in the spring, early summer or autumn, or by division or from root cuttings. Also, annual self-seeding.
Pests, diseases or disorders
Border cultivars may be prone to slug damage in damp situations and to attack by root aphids when grown in very dry conditions or in pots.