They are especially active in periods of cool wet nights and warm humid days, causing leaves to wilt and die. Plant delphiniums on well-drained, fertile soil with enough space between them to encourage good air circulation. ... Try to keep their foliage dry by watering just the soil.

Why do my delphiniums keep dying?

why are my delphiniums dying? Delphiniums that have sat cold and wet through winter may die, so ensure good drainage and use a mulch over winter. A slug attack when the plant is young might also impact vigour and cause the plant to fail. You should also check for black blotch.

What is killing my delphinium?

A: The problem bug is called a delphinium worm. There are some physical controls you can try to help solve the problem. Since the worm spends the winter in the hollow stems of the plant, cutting the plants to the ground in the fall is important. Do not put the stems and leaves on your compost pile but dispose of them.