Pruning plum trees is straightforward, once the trees are established, and consists mainly of thinning out overcrowded wood. More detailed pruning is, however, necessary in the early years in order to build up a suitable framework.
Pruning A 1-Year Old Plum Tree
Bare Root Trees: If a bare root tree is purchased and planted, pruning may be carried out after planting in late winter. Usually, trees purchased bare root are 1-year old will have small branches that can be pruned with sharp hand pruners.
A bare root plum tree typically has a main trunk about 4' in height before the branch system begins. After the bare root tree has been planted it should be pruned to a bud along the trunk, 9 to 12 inches above the height of the lowest branch desired. During the season shoots will grow from buds below this top cut, and from these will be chosen 5 to 7, which will be the main branch system. The top bud/branch will grow strongly; this can be offset by making a nick below it with a knife, forcing more growth into the lower buds/branches. Wide angled branches can be encouraged by making small notches in the bark above selected buds/branches. The topmost shoot can be removed later. Any growth arising below the position of the lowest branch should merely be shortened for the first year or two before removing, as they assist in thickening the stem.
During the first year or two after planting a bare root plum tree, the 5 to 7 selected main branches are subsequently pruned to a suitable outward pointing bud, with one third to one half of the new wood being removed. Afterwards this is reduced to mere tipping which is discontinued altogether eventually.
Basically speaking, when pruning a bare root plum tree, what you're shooting for is a tree that will consist of 5 to 7 well-spaced main branches, from which will grow the lateral stems that will form the bulk of the fruiting wood.
Pruning a 2 to 3 year Old Plum Tree
If the tree has been purchased as a 2 or 3-year-old (usually container grown and purchased from your local nursery and garden center) it is advisable to defer pruning for one year after planting. The branch system of such a tree will already have been formed by the grower. After the framework of the tree has been formed, subsequent pruning will consist of cutting out dead and diseased wood, badly placed crossing branches, or groeth that is too upright too upright, ensuring that the growth remaining is well spaced.
