You can prune an apple tree any time of the year without hurting it, but late winter is best. The worst of the cold weather is past, so you won’t subject the fresh cuts to severe icing, but you will still be able to influence the tree’s spring growth.
There are several objectives to pruning an apple tree, says Pat Patterson, Oregon State University Extension Service master gardener:
- Controlling the height of the tree, so most of the fruit doesn’t grow out of reach.
- Developing good limb structure for strength, fruit production and general health of the tree.
- Encouraging plentiful new limbs.
- Ridding the tree of damaged or diseased growth.
The overall size of the tree depends primarily on its rootstock and innate vigor. Most apple trees are grafted onto dwarf or semi-dwarf rootstock.
When you plant an apple tree, don’t bury the graft, where the fruiting stock joins the rootstock. This ensures the fruiting stock will not begin to produce its own roots and the tree will keep its dwarf or semi-dwarf height. Even so, you will want to monitor the height of your tree to be sure it doesn’t outgrow the spot you’ve picked for it. Once it’s as high as you want it to be, prune the central leader—the main upright limb—back to a lateral branch. Monitor the height year to year.
“Don’t expect a new young tree to start bearing well until probably its fourth or fifth year,” Pat says. “In the long run, the tree will do better to put its energy into root and limb growth rather than fruit for those first few years.”
Look for limbs that branch from the central leader either too sharply upward, forming an acute angle, or at too wide an angle. Acute angles tend to trap bark as they grow and can lead to splitting.
Branches that grow at too great an angle from the vertical tend to be weaker. They also encourage water sprouts, the unproductive upright shoots that need to be pruned off mid-summer every year. The ideal angle between the central leader and lateral branches is about 60 degrees.
Encourage branches to grow toward the outside of the tree. Eliminate those that grow toward the center or cross other branches. You want air and light to penetrate the foliage to the center of the tree as much as possible.
“Different kinds of apple trees have different ways of setting fruit buds,” Pat says. “This is obviously very important for how we prune the tree so as not to cut off the fruiting wood. If you’re in doubt, as long as you know the name of your tree, you can ask at your local nursery or look it up in a good garden book or online.”
Once the tree has matured and begins to produce fruit, expect new branches to bear their best for several years and then taper off. Prune older branches that have begun to produce less.
Summer is a good time to remove older branches because it is obvious which branches are producing best and which should be pruned. Summer pruning also allows you to get rid of branches showing signs of damage or disease.
Beyond these basics—which also apply to other similar fruit trees, such as pears—there are many fine points to pruning a fruit tree. The OSU Extension Service offers several helpful publications:
- Pruning to Restore an Old, Neglected Apple Tree, https://catalog.extension.oregonstate.edu/ec1005.
- Managing Diseases and Insects in Home Orchards, https://catalog.extension.oregonstate.edu/ec631.
- Growing Tree Fruits and Nuts in the Home Orchard, https://catalog.extension.oregonstate.edu/ec819.
- Training and Pruning Your Home Orchard, https://catalog.extension.oregonstate.edu/pnw400.