Principles to keep in mind before pruning young trees: You can read my prior post about pruning here. You can also read all this information here.
- Every cut has the potential to change the growth of the tree. Always have a purpose in mind before making a cut.
- Proper technique is essential. Learn where and how to make the cuts before picking up the pruning shears.
- Trees do not heal the way people do. When a tree is wounded, it must grow over and compartmentalize the wound. As a result the wound is contained within the tree forever.
- Small cuts do less damage to the tree than large cuts. For that reason training of young trees is critical. Waiting to prune a tree until it is mature can create the need for large cuts that the tree cannot easily close.
Making the first cut is critical to a tree's response in growth and wound closure. Make pruning cuts just outside the branch collar. Because the branch collar contains trunk or parent branch tissues, the tree will be damaged unnecessarily if you remove or damage it.
Establishing a strong scaffold structure: A good structure of primary scaffold branches should be established while the tree is young. The scaffold branches provide the framework of the mature trees. Properly training young trees will develop a strong structure that requires less corrective pruning as they mature.
Trunk development: For most young trees, maintain a single dominant leader growing upward. Do not prune back the tip of this leader. Do not allow secondary branches to outgrow the leader. Sometimes the tree will develop double leaders known as co-dominant stems. Co-dominant stems can lead to structural weaknesses, so it is best to remove one of the stems while the tree is young.
Permanent branch selection: How a young tree is trained depends on its primary function in the landscape. Ex. street trees must be pruned so that they allow at least 16 feet of clearance for traffic. Most landscape trees require only about 8 feet of clearance. Branches should be well spaced radially and along the trunk. A good rule of thumb for vertical spacing of permanent branches is to maintain height. Thus a tree that will be 50 feet tall should have permanent scaffold branches spaced about 18 inches apart along the trunk.
Using the right pruning tools: For small trees, most of the cuts can be made with hand pruning shears (secateurs). The scissor-type, or bypass blade hand pruners, are preferred over anvil type. They make cleaner, more accurate cuts. Cuts larger than one-half inch in diameter should be made with lopping shears or a pruning saw. Never use hedge shears to prune a tree. Whatever tool you use make sure it is kept clean and sharp.