The American plum is a member of the Rosaceae family that grows wild in most of the United States. It is an awesome sight in the early spring when covered with small white flowers while most of the landscape is still gray and dormant. The trees grow up to 20 feet tall and spread out to take over the landscape without proper control. In many areas, the American plum is considered a nuisance plant. The tree is easy to grow but requires consistent work to control it.
Choose a well-drained site with plenty of sun. If you are planting American plum for the fruit, plant two trees within 50 feet of each other for best pollination. Mix a thick layer of organic compost into the top 10 inches of soil.
Plant seeds in the fall. Remove seeds from overripe fruit. Clean and dry the seeds, and plant 1 to 2 inches deep.
Soak the roots of bare-root trees in water for an hour or two before planting. Dig a hole large enough to accommodate the tree. Place the tree in the hole, and spread out the roots. Fill the hole with soil about 3/4 full; then water it well. Finish filling the hole and water again.
Place a layer of organic mulch around the base of the plant to conserve moisture and discourage weeds.
Water the plant regularly during dry weather, but do not over water.
Fertilize in the early spring and mid-summer with 10-10-10 fertilizer.
Remove suckers that sprout at the base of the tree. The tree will spread if not controlled.
Protect the plant from frost after budding. Cover the plant with fabric when frost is predicted in the spring. If the weather is extremely cold or sustained cold is expected, add a small heat source such as a light bulb under the tent.
Thin the fruit when it is about the size of a marble. Remove the smallest fruits so that plums are at least 5 inches apart. Thinning prevents the branches from breaking under the weight of a large crop and encourages larger fruit.
Harvest fully ripe plums by hand or by placing a tarp under the tree and shaking or lightly beating the branches. The American plum ripens in mid-summer through late fall, depending on your location and growing conditions.