There are a couple of different reasons why a weeping willow tree will need trimming or pruning. Willows are vigorously growing trees whose smaller, leafy, limbs droop down to the ground in all directions. This can become a nuisance when mowing are gardening around a weeping willow unless they are trimmed back well above eye level. Wind and weather can also cause damage to a weeping willow by breaking off large limbs and branches. This will require pruning of the affected area to reduce the damaged limb's exposure and reduce rot potential. Larger limbs that have formed bark can be pruned in late summer to early fall, while green leafy sections can be trimmed any time of year.
Trim the slender leafy limbs of a weeping willow hanging down to the ground by using large pruning shears or a hedge trimmer. Make sharp even cuts each time to prevent damage to the limbs. Sharp pruning shears will allow for cutting several of the small green limbs at one time.
Prune back larger limbs that have either been damaged by the wind or some other force by using hand shears or a pruning saw. Again, it is important that these tools be sharp and that you make even cuts in such a way to limit the exposed wood once limb is cut free. Limbs that can be trimmed or pruned in this way can range in sizes up to 1 1/2 inches. Larger diameter limbs will require larger tools.
Cut back very large limbs in the late summer or fall with a large pruning hand saw or chain saw. When cutting a large limb from a weeping willow, several cuts should be made along the length of the limb while working back toward the base. Often when the first cut is made at the trunk of the tree, the weight of the limb will tear away from the trunk before it is completely cut through, and could cause irreparable damage to the tree.
Rake up and haul trimmed limbs and fallen leaves away from the site and dispose of them in a compost pile for recycling.