Semi-dwarf apple trees are some of the most popular varieties of all fruit trees, especially for the backyard gardener. These trees stay at a relatively manageable size, which makes pruning and harvesting much easier than the standard sized trees. Even though these trees have the potential to be easier to care for and produce very tasty fruit, they also must be cared for properly. There are many things to consider when it comes to pruning a semi-dwarf apple tree. Understanding the proper technique will help you get the most life out of the tree.
Determine whether you want to prune according to the central leader method or the modified central leader method (see References). No matter which method you choose, all low branches should be pruned off of the tree, or the tree will have too many competitive parts all vying for the same resources.
Wait until near the end of winter before making any cuts. This helps by giving the tree time to heal before the pests of spring invade and begin possibly attacking weak points in the tree.
Use the clippers to help cut a central leader that is straight and going in a vertical or near vertical motion. If using the modified central leader, make sure you have no more than four parallel branches and choose ones that are at the widest angles, or angles of at least 60 degrees.
Inspect all the other branches once the central leader or leaders have been chosen. If any branches cross each other, remove one or the other so there is no conflict and they do not grow together.
Thin out the branches even more so that there are distinct levels or scaffolds on the tree. This provides the tree enough sunlight on each level so that there is less chance of branches getting deprived of sunlight, which is essential for good fruit growth.
Prune the tree to a conical shape if using the central leader system to help further ensure good access to light. The conical shape is very popular for semi-dwarf apple trees and is used more for them than standard trees.