If a plum tree goes without proper feeding, it can lead to stunted growth and limited productivity. Feed your plum tree with fertilizer to increase its nutrient content, recommends the Ohio State University Extension. Fertilize regularly when caring for plum trees, unless the trees are able to absorb nutrients from fertilizer you use on your lawn.
Fertilize your plum tree in early spring before buds begin to break out and when hard frosts are no longer expected.
Use your rake to pull back any mulch around the bottom of the tree.
Spread the 10-10-10 fertilizer evenly, beginning 2 feet out from the trunk and spreading away from the tree, until you are slightly out from under the tree's branches. Use 1 cup of fertilizer for each year the tree has been planted. If you planted the tree two years ago, use 2 cups of fertilizer. The maximum amount of fertilizer is 1 pound on trees older than 10 years.
Replace the mulch around the bottom of the tree.