For best fruit production, sweet cherry trees should be pruned annually. The fruit of the sweet cherry tree grows on spurs (spurs can be productive for 10 to 12 years) that are formed on older wood. Major pruning is done when the tree is young to form its growing structure; mature trees will require minimal pruning. The sweet cherry tree is generally tall and upright. It should be trained to grow with a central leader and 4 to 6 main scaffolds, or branches, that are 8 to 12 inches apart. Pruning objectives: remove broken, damaged or diseased branches; remove branches to form a good scaffold structure; control and maintain the shape and size of the tree; and limit the height of the tree.
First prune away any dead, damaged, broken or diseased branches. Make your cut at the breaking point or by removing the entire branch---this is a judgment call that depends on where the break or damage has occurred. Make a clean diagonal cut that leaves no torn or ragged edges. Clean cuts promote proper healing. This type of pruning can be done whenever damage or disease occurs (the tree does not need to be in its dormant stage).
Visually inspect a young sweet cherry tree to determine which branches are going to form the main scaffold branches. Choose branches that form a wide crotch.
Eliminate the branches that are not going to make up the scaffold structure by cutting them off where they join the trunk. This should be done in early spring while the tree is still dormant. Once a young tree has been trained and the scaffold structure formed, pruning will mainly be limited to removal of diseased or broken branches.
After the first year, look at the height and width of the tree to determine whether you need to cut back the leader and/or head back the scaffold limbs. Remember, you want to keep the tree low for spraying and harvesting. Cut the leader back if it is more than a few inches longer than the scaffold/lateral branches, and head back lateral branches as necessary to maintain the tree's shape. Cut just above a bud. This procedure should also be done in early spring.
Cut off any suckers (shoots that grow from the bottom of the trunk or up from the roots). These deprive the tree of nutrients. You can prune suckers at any time of year.