The Kilmarnock willow (Salix caprea 'Pendula') is usually grafted upon another willow tree trunk to create a large mounding shrub or small weeping tree for use in ornamental garden displays. Growing 5 to 6 feet tall (or more if the graft on the trunk is higher) and 6 feet wide, it develops a dense head of thick yellowish brown twigs that bear gray and yellow catkin flowers in spring. Eventually, grayish green leaves emerge. Grow Kilmarnock willow in USDA hardiness zones 6 through 8.
Trim the tips of any branches that are dragging on the ground. Make the cuts with hand pruners 1/4 inch away from a dormant bud or leaf on the drooping branches so the branch tip after pruning is 6 to 12 inches above the soil.
Remove vertical branches that jet up from the dense, weeping head of the Kilmarnock willow. Although these upright branches will eventually weep over with great length, they will change the size and character of your plant. Make pruning cuts to remove the upright errant twigs 1/4 inch above the point of attachment at their base. Extension horticulturists at Kansas State University recommend removing smaller upright twigs first before large ones; this allows you to visualize the plant and view your pruning work as it progresses.
Scan the weeping mass of branches in the willow and look for any dead, diseased or broken twigs. Prune these away. Also look for any branches that are growing horizontally across the interior of the plant. This should also be pruned, because they do not allow air and sunlight to penetrate into the center.