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Types of Plums: Plums can be divided into three different groups--European, Damson and Japanese. Familiar varieties of the European type are Stanley, Reine Claude (Green Gage) and the French and German prune (Fellenburg) types. The European-type plums are best for eating fresh and for canning. Damson-type produce very tart fruit which is used chiefly for cooking and preserving. Examples of Damson-type plums are Shropshire and French Damson. Japanese plums are generally not satisfactory in the Northeast, due to frequent loss of crops to poor pollination and spring-frost injury. Examples of Japanese plums are Methley, Shiro, Ozark Premier, Burbank and Elephant Heart. Planting: An important consideration in selecting plum cultivars for planting is that of pollination requirement. Trees of some plum cultivars are capable of setting and producing a crop if grown as single isolated plants. Other plum varieties that do not self-pollinate require cross pollination for fruit set and development. This means that trees of at least two cultivars with overlapping bloom periods must be planted. Standard plum trees usually begin to bear fruit three to five years from planting. The trees have a useful life of 15 to 20 years and come into full production in about 10 years. Yields of 3 to 5 bushels per tree may be expected, depending on cultivar. Nursery Stock: Desirable nursery stock for planting consists of trees 3 to 6 feet tall with a trunk diameter of 3/8 to 3/4 inch. Plum trees should be planted in early spring. Standard-size plum trees should be spaced at least 20 feet apart in fertile, well-drained soil. Cultural Practices: Important cultural practices in plum production are pruning and training, fertilizing, mulching, and pest control. Plum trees of the European type are best pruned and trained to the modified central leader system. In this system, several well spaced side or lateral branches (scaffolds) are allowed to develop from the main trunk or leader of the tree. When the tree reaches the desired height, the central leader is cut to a short lateral branch. Plum trees should be fertilized annually for best growth and development. Suggested fertilizer practice consists of an early spring application of 1/20 pound of actual nitrogen (8 ounces of 10-10-10) fertilizer per year for each year of tree age. Mulching with an organic mulch such as straw, sawdust, wood chips and similar materials can help conserve valuable soil moisture and help control weeds under the tree. Common pests and diseases of plum trees include plum curculio, European red mite, brown rot, leaf spot and black knot. See specific GreenShare Factsheets on these pests and diseases for more information and control recommendations. Harvesting and Storing: High quality plums are well shaped, colored, firm and free from defects such as bruising and insect and disease damage. Without a good knowledge of plum cultivar (variety) characteristics, it is difficult to detect when a plum is ripe by color alone. Plums may be various shades of red, blue, green and yellow. The best way to determine plum ripeness is to apply gentle pressure to the fruit with the thumb and feel if the flesh is beginning to softenÜif so, the fruit should be ready for consumption. If not, allow the fruit to ripen for a day or so at room temperature. With experience with a particular variety, one can soon correlate color with taste and judge when the fruit should be harvested from the tree. Ideal storage conditions for plums consist of maintaining a temperature of 31 to 32 degrees F and a 90 to 95 percent relative humidity. Under such conditions, storage life of plums is from two to four weeks. For many, the home refrigerator will be the best method of preserving the after-harvest life of the fruit until it is consumed or preserved.
Adapted from Richard C. Funt, Ohio State University Extension, 2000
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