Question: I need help pruning three shade trees which I planted last year that are now about 10 to 12 feet tall. They had bare trunks up to 4 feet when I planted them. Is it time to prune up to 6 feet now? A few small sprouts have developed below 4 feet.
Should I remove those? The top of one tree was broken and now has three sprouts. Answer: Most shade trees do best if they have a single trunk. So, your first job is to pick the straightest sprout and remove the other two.
University research has shown that young trees develop a stronger lower trunk if lower branches are allowed to develop below 6 feet but are pruned so they only grow about 12 to 18 inches in length. These lower branchlets feed the lower trunk where they are attached and cause it to grow to a larger diameter more quickly. These short lower branches can be removed after there is at least 8 to 10 feet of growth above them.
When the time comes to remove them, small branches should be pruned flush with the trunk. When branches larger than 2 inches are removed, a one-half-inch collar should be left where it is attached to the trunk. The healing tissue to repair the wound is located in this collar tissue.
Most shade trees need some thinning of inner branches to remove those that are crossing or rubbing against each other. In choosing which branch to cut, remove those growing inward or upward. The horizontal, outward-growing branches are the strongest.
No more than one-fourth to one-third of growth should be removed .