Although plum trees are not incredibly difficult to care for, they are not for the completely inexperienced gardener. Fortunately, even a small amount of experience growing fruit trees will help enormously in caring for plum trees.
Fertilize your plum once in early spring and once in midsummer. You can use commercial fertilizer or compost, which you should apply around the base of the tree but not touching the trunk. Water during dry spells. Water plum trees growing near walls or fences more often.
Thin the fruit. Thinning the plums keeps branches from breaking and ensures a healthy crop of fruit. You can thin the plums first in mid-May and again in July. Remove diseased or damaged plums first and then thin the plums to leave three inches of space between each plum.
Prune your plum tree to shape it and prevent silver leaf disease. Do major pruning in the spring, while the trees are still dormant. While pruning, avoid splintering the wood by cutting as cleanly as possible. Burn the dead or diseased wood. Use a protective sealer on cuts after pruning larger branches.
Cut away suckers and watersprouts. Suckers are tall shoots that grow near the base of grafted plum trees. Watersprouts grow from the main branches and trunk.
Control weeds and grass to keep both at least three feet away from the base of the tree. Place mulch around the base of the tree, but make sure the mulch doesn't touch the trunk of the tree.