The Black Ash grows to be 30 to 60 feet tall. It has a tall trunk with ash-gray bark. The branches and leaves grow fairly uniformly, creating a somewhat narrow spread. The black ash thrives in wet places such as peat bogs, cold swamps and stream bottoms. It grows in northern areas including the Great Lakes region and southeastern Canada. Pruning black ash when it's young helps it produce a strong structure. As the tree matures, pruning will maintain the tree structure, health, form and appearance.
Prune the black ash during the dormant season, in the fall or winter. Consider the spherical form which means it has many lateral branches that may compete for dominance. If you attempt to prune the tree into an unnatural form, you'll have to do continual maintenance.
Use a hand pruner to cut small, thin branches. Lopping shears or small pruning saws with bigger cutting surfaces and greater leverage can be used for slightly larger branches. If you're dealing with even larger branches, about six inches in thickness, use a pruning saw. Chain saws will work on those thicker than eight inches.
Plan to make cuts at the node, which is where one twig or branch meets another. Each spring, growth will start with buds. Twigs grow from the buds, eventually creating a new node.
Cut throughout the black ash's crown to increase the amount of light and air that gets to the tree. During this process, you will develop and maintain the tree's form and structure. Do not remove more than one-quarter of the crown at a time or you may cause stress and excessive production of epicormic sprouts, which are shoots that grow out of latent buds.
Keep all branches that are attached with strong U-shaped joints. Remove those branches with narrow, V-shaped connections because they are weaker and are likely already cracked.
Raise the black ash's crown by removing all the branches that are facing downward, at the bottom of the tree. This will provide clearance for pedestrians, traffic and lines of site. The tree will also have a neater appearance.