The mountain ash tree is native to Europe, although it's grown all over the cooler part of the U.S. Hardy from USDA hardiness zones 3b to 6b, the tree grows to about 30 feet with a 25 feet spread. The flowers are white and showy in the spring with red berries that appear in the summer and last through the fall. Moderate pruning keeps the mountain ash looking good all season long.
Prune mountain ash in the late winter right before spring, while the tree is still dormant.
Cut off any damaged, dead or diseased branches as they occur on the mountain ash. Cut the branches off at the branch collar, the spot that bulges right before the branch reaches the trunk.
Cut off crossing branches and weak branches throughout the mountain ash's crown, cutting at the branch collar.
Prune off any low branches that impede movement under the tree.