When to lightly prune
Prune in late winter or early spring. Some deciduous trees and shrubs, such as birch (Betula) bleed if pruned in late winter. To facilitate rapid healing of cut surfaces, prune these in late summer or early autumn instead. Deciduous magnolias are also pruned in late summer to reduce risk of dieback.
Deciduous azaleas and lilac (Syringa) should be pruned immediately after flowering.