Native to North America, ash trees are good landscaping choices for homeowners with a large yard. These trees can grow throughout most of North America and display colorful fall foliage. Ash trees should be pruned annually in the late spring, after frost danger has passed for your area. The University of Illinois cautions against pruning ash in June or July since this can invite an ash borer infestation.
Inspect your ash tree's branches for signs of dead, damaged or diseased limbs. These need to be removed for the overall health of the tree. Diseased limbs will be physically marred, while dead limbs feel hollow to the touch and damaged branches display bruises and nicks.
Prune away dead, diseased and damaged branches by cutting them off at the base. Do not cut into the tree trunk or the tree collar, the swollen tissue where the limb meets the trunk. Use your lopping shears for small branches and the hand saw for those over 1-1/2 inches in diameter.
Remove dead, diseased and damaged branches to your trash bin. Do not compost them since this could spread disease. Before continuing to prune your ash, disinfect the pruning tools with a 1:10 solution of bleach:water. Dry them thoroughly before returning to work.
Cut off downward-growing branches and low-growing branches that interfere with movement under the tree, if it's a mature ash tree. Snip these off at the base with the lopping shears or hand saw.
Thin out weak interior branches in areas of the tree canopy that are crowded with new growth. Identify weak shoots and prune them back to the originating limb. This will improve air circulation, which helps keep your ash tree healthy.
Cut back limbs to encourage new growth, reduce tree size or shape the ash tree. Clip back the tips of branches until they reach the desired height.