The best season to prune apple trees is early spring, after winter’s coldest weather is likely past, but before ‘bud break’ when spring growth begins. February through early April works well most years in our Upper Midwest region. Knowing when to prune is easy; knowing what to prune is trickier.
Why it’s important to prune apple trees:
- Pruning increases fruit production and quality.
- Maintains the tree at a better height for picking.
- Prevents disease by increasing air circulation.
- Reduces the tendency of many varieties to bear heavily only every other year. It levels out this ‘biennial’ bearing habit.
If left unpruned, apple trees can become too tall with the best fruits high up and out of reach. Branches within the canopy grow crowded, reducing flowering and fruiting. Overly-long upper branches shade the lower branches, which decreases their fruiting. The tree is more susceptible to leaf diseases, because air doesn’t flow through the branches.
What does a well-pruned apple tree look like: Start by imagining a well-pruned, well-bearing apple tree. Research favors the ‘central leader system’ in which a single central trunk runs the height of the tree, with strong side branches, called scaffold branches, radiating outward. The tree’s shape becomes pyramidal, with one central branch, called the leader, always the highest point. Side branches are narrower at the top of the tree, and become progressively wider, until the widest, outstretched branches are lowest on the tree. The tree becomes shaped more like a Christmas tree than a round globe. The pyramidal shape allows all branches to receive greater sunshine, which encourages more flowers and fruit, especially on lower branches.
Tips for pruning a very young, or newly planted apple tree:
- Pruning is best started the day you plant the tree.
- If there is more than one central leader, remove one. I’ve often noticed trees sold with a perfect ‘V’ at the top. One side needs to go. The remaining leader should be shortened by about one-third. .
- Shorten side branches to create a pyramid-shaped tree. Let the lowest branches be the widest out, and shorten side branches progressively as you move up, resulting in a tree shaped like a Christmas tree. Side branches are usually too close together on young trees, but we’ll remove some to increase spacing as a few years go by.
Tips for pruning an apple tree that’s already bearing (about 7 to 15 years old):
- If the tree’s shape is currently a round globe, prune the tree into the pyramid-shape described earlier. Start with the lowest branches, which will be the widest out. As you move up the tree, shorten branches in stair-step fashion until the top is the narrowest point.
- Branches along the central trunk are usually too close together. The main horizontal scaffold branches should be spaced 12 to 24 inches apart along the trunk. Remove excess branches back to the trunk, just a little out from flush, leaving the branch ‘collar.’
- After shaping the tree and establishing a network of scaffold branches, prune out inner crisscrossing branches, and branches pointing backwards into the tree. Branches should radiate outward.
- Remove downward-pointing growth.
- Always remove sucker growth from the tree’s base, and any dead wood.
- If your apple tree has never been pruned, it might take several years to re-shape.
Tips for pruning an older apple tree:
- If your apple tree is old, overgrown, and any fruit is high out of reach, a rejuvenation is in order.
- Remove about one-third of the tree’s height each year for three years, attempting to get the tree down to about 12 feet high. Don’t “dehorn” the tree, but prune branches back to side growth.
- Let the lowest branches be the widest out, and strive to shorten progressively as you move upward on the tree.
- Remove the clutter from inside the tree, following steps in the preceding section.