Proper pruning intensifies the spring bloom of ornamentals like flowering plum by encouraging a denser crown. If the main crop were fruit, pruning during the dormant season in late winter would shape the tree and forestall problems with heavy fruit crops and broken branches. Since the spring bloom is the flowering plum's best feature, growers shape these trees shortly after the tree flowers.
Flowering plums bear flower buds on wood that grew the previous season. Thinning the crown during the winter reduces the number of flowers the next spring. Neglecting pruning causes shaded branches to die back and also decreases the intensity of the bloom. After the blooms fall and before the tree leafs out, prune out up to one-third of the crown to allow room for new growth. Cutting back to the midpoint of a twig or branch causes new branches to sprout below the cut. Use that method to help fill in existing gaps in the canopy with sprouts from nearby branches.
Trimming out storm-damaged branches during the summer allows the tree to heal quickly and avoids problems with insects and fungi that attack the injured wood. To treat the problem correctly, find the branch collar at the base of the injured limb. At every branch junction you'll see a swelling ring of bark. Always cut within 1/2 inch of that collar, without damaging the collar's bark. The tree quickly seals off the wound and heals the cut with a layer of new bark.
Fast-growing vertical shoots called suckers erupt from branches, roots and trunks of many types of fruit trees during spring and summer. Unchecked, these sucker shoots draw off much of the tree's energy and mar the tree's shape. A sucker shoot growing from the base of a grafted tree could outgrow and replace the grafted section. Cut suckers back to the branch collar while still small.
During the dormant period inspect the flowering plum tree for damaged or diseased limbs. Leave crossed or crowded branches for the spring pruning. Trim out any dead wood you find, along with any branches which show signs of disease. Dead wood provides a starting point for insect infestations and diseases. If you find raised patches of insect eggs glued to twigs, rub them off with gentle pressure instead of cutting off the twig. These egg clusters hatch into colonies of tent caterpillars in the springtime. Spraying with dormant oil suffocates exposed insect eggs and prevents major insect damage.