Pruning your plum tree (Prunus domestica) each year not only gives you bigger, better quality fruit at harvest time, it also reduces pest problems and helps the tree live longer. Plum trees thrive in U.S. Department of Agriculture hardiness zones 5 through 9, with some variation according to variety.
Japanese variety plums (Prunus salicina), such as 'Beauty Plum’ -- hardy in zones 6 through 10 -- are round or heart shaped rather than elongated like the European plum varieties. Both types of plum trees should be pruned using the same methods.
Prune plum trees during the late winter to early spring dormant season before new growth begins. Prepare for pruning day by gathering the correct tools and equipment.
Pruning to an open-center shape allows sunlight to reach the inner canopy of the tree. Sunlight encourages fruit to grow on the inner branches. These are called fruit spurs. An open center pruning plan consists of the 2 1/2- to 3 1/2-foot-tall trunk and three or four scaffold branches, which grow outward rather than upward.
According to the University of California Backyard Orchard website, "Folding ladders and extension ladders are unsafe and not designed for unstable ground or tree work. An orchard (tripod) ladder is the only ladder considered acceptable and safe, even on hillsides and uneven ground. Properly cared for, an orchard ladder will last a lifetime and more."
Select three or four strong branches growing at an 80 to 90 degree angle from the tree trunk to serve as scaffold branches.
Remove all dead and broken branches, all suckers and water sprouts. Water sprouts are branches that grow vertically from the trunk and main branches. Suckers grow from the root stock out of the base of the tree trunk.
Remove all branches and twigs that cross each other. Branches that rub against each other invite disease. Make clean cuts flush with the branches that will remain.
Remove all branches except the three or four scaffold branches. Maintain the scaffold shape each year by pruning away branches that grow straight up or cross other branches.
Following this basic pruning plan, your plum tree will thrive