• Thinning plum trees is important to prevent branches from breaking under the weight of the fruit. If branches do break, prune them back to undamaged wood, ideally cutting back to a natural fork to avoid leaving stubs.
• Be sure to water the young trees heavily every week during the first growing season to help promote growth. Then, water regularly. It’s best to water the plant deeply at the soil line, then let the soil dry out (though not completely) and water again.
• Water your tree well into mid-October to give it plenty of moisture through the winter months.
• Do not fertilize young fruit trees until they have set a crop.
• Once established, fruit production requires regular fertilizing all year long. If there’s good fruit set, fertilize with one pound calcium nitrate per tree or 1½ lb. 10-10-10. Cut back the nitrogen in fall and winter to avoid encouraging new growth in those seasons.
• In the fall, rake away all debris and fallen trees.
• Prune in early spring or mid-summer to avoid infection. The best time for pruning is usually spring for young trees and mid-summer for established ones.
• Do NOT prune in the fall or winter injury and infection may occur.
• Are you having pest issues? Talk to your local cooperative extension or garden center about a spray program.
• To help control pests and diseases, remember to prune your trees to keep them open. You can also mulch around the trees in the spring to help control weeds, but be sure to remove the mulch in the late fall so that no pests use it over the winter. You can also lightly cultivate the soil around your trees in late spring to eliminate any pests in the soil.
• To prevent winter injury: Consider a tree wrap or guard around the lower trunk, especially for a young plum tree.
• Keep an eye on the lower bark and branches for mouse or rabbit damage; if this could be a problem, you may need to install tree guards or fence in young trees with chicken wire for the winter.

Pruning: Japanese Plum Trees

• If you have a Japanese variety, the best pruning method is to create an “open center” shape, where the central trunk is cut short and several large branches radiate outwards from it’s tip. In the summer of the first year, cut the vigorous shoots that form on the top of the tree by two or three buds. After about a month, check the tree. As soon as you have three wide-angled branches, spaced equally apart, cut back any other branches so that these three are the main branches. In the early summer of the second year, cut back the branches in the middle of the tree to short stubs and prune any shoots developing below the three main branches. After the third year, remove any shoots in the center of the tree to keep its shape.
• Japanese types require heavy pruning to help keep them in shape and to produce better fruit. It is also good to thin out the fruit on these types of trees. You should space the plums about 3 to 4 inches apart on each branch.

Pruning: European Plum Trees

• If you have a European variety, the best pruning method is to create a central leader. This shape features a central trunk with branches that spiral out every 5 to 8 inches, making sure that no branch is directly above another. The training for such a system begins in the early summer of the first year, during which time you should remove any shoots that form within 18 inches of the ground. The end result should resemble a Christmas tree.
• European types do not require fruit thinning because they do not produce as much fruit as Japanese types. However, the fruit on these types should be spaced about 2 inches apart on each branch.

For more pruning tips, check our spring pruning guide.