Cornus alba and other shrubs greatly benefit from an occasional hard pruning to maintain form and colour.
Drastic action is required.
The same Cornus alba cut back to within five centimetres of its base in late winter or early spring. New stems will be brilliant red. Few gardening chores are approached with more trepidation than pruning. In reality, it's a relatively simple process that requires a little basic knowledge, some common sense and the proper tools. The number-one rule of pruning is don't fight nature.