Most willow trees thrive in damp, well-drained soils. Like other trees, willows require occasional pruning to help them retain their shape, provide starts for propagation and remove diseased growth.
The best time to perform heavy pruning on your willow tree is after it loses its leaves in the late fall or winter. The bare branches allow a clear view of the tree's form, enabling you to cut the overgrowth away quickly and easily. Avoid heavy pruning for shaping purposes during the summer months, when the presence of disease pathogens increases the risk of damage.
The best time to prune off damaged or diseased branches is as soon as they appear, regardless of the season. Disinfect your pruning shears with a solution of 1 part household bleach to 9 parts water, dipping the shears after each cut. Remove damaged growth about 5 cm (2 inches) above the affected portions.
Many types of willows propagate readily from vegetative cuttings. The best time to prune sections for propagation purposes is in the spring. Select just a few branches from each willow tree, removing just the top 25 to 37.5 cm (10 to 15 inches) of pliable branches containing numerous leaf buds. Inserted in a solution of water and rooting compound, these branches often form new roots.