There are several types of plums. Make sure the type selected is hardy in Michigan. Some of the varieties are partially self-fruitful but it is best to grow two varieties to insure the largest possible crop. Most varieties will pollinate other varieties if they are of the same type. For instance, most European varieties will pollinate all other European varieties. Plums bear heaviest on 2 to 4 year old wood and a tree should be productive for up to 15 years.
European plum fruits are egg shaped, sweet, and the flesh is dry. These plums are used for prunes. The Japanese plums are larger but less hardy and have large, juicy fruit. Japanese plums also have a tendency to grow too much and bear crops that are too heavy.
European Plums Early Cultivars
Earliblue - Blue fruits produced in moderate numbers. Use Mowhawk as a pollinator.
Damson - Small blue fruits suitable for jam, jelly or preserves. The trees are self-fruitful. Green Gage (Reine Claude) - Greenish fruit can be used fresh or cooked. Trees are self-pollinating. Stanley - Large blue fruits produced in large numbers, a self-pollinator. Sugar - Large, sweet, blue fruits suitable for drying or canning. The trees are self-fruitful but bear heavily in alternate years only with light crops in the off year. Yellow Egg - Yellow fruits, self-fruitful. Bluefre - Blue, freestone fruits. The tree is self- pollinating and is mildly susceptible to brown rot.
President - Very late ripening of large blue fruits. Suitable for cooking or canning. Use another European plum as a pollinator.
Japanese Plum Cultivars Early Cultivars
Beauty - Good for fresh use or cooking. Self-fruitful but yields are increased if pollinated by Santa Rosa. Bruce - Large fruits, use Santa Rosa as a pollinator. Early Golden - Small, yellow, freestone fruits. A tendency to alternate bearing. Use Shiro or Burbank as pollinators. Santa Rosa - Large reddish fruits good for eating fresh or canning. Self-fruitful but yields are better with cross pollination. Abundance - Good for fresh use or cooking. Tree tends toward alternate bearing. Use Methley or Shiro as pollen sources. Methley - The fruits ripen over a longer period of time so needs several pickings. Self-fruitful but produces better crops if pollinated with Shiro or Burbank. Satsuma - Good for fresh use or preserves. Pollinate with Santa Rosa or Wickson. Shiro - Yellow fruits suitable for eating fresh or cooking. Suggested pollinators are Early Golden, Methley, or Santa Rosa.
Burbank - Good for fresh use or canning. Early Golden or Santa Rosa are good pollinators. Duarte - Fruits keep well and are tart when cooked. Pollinate with Santa Rosa or Satsuma. Howard Miracle - Fruits rather acid and with distinctive flavor. The tree is a self-pollinator. Ozark Premier - Very large fruits, the tree is self- pollinating.
Elephant Heart - Fruits large and have red pulp. Pollinate with Santa Rosa.
These cultivars were bred for hardiness: Pipestone, Superior, Toka, Underwood and Waneta. Superior can be used to pollinate Pipestone, Toka, Underwood, and Waneta. Use Toka to pollinate Pipestone or Superior.
The open center method is used on plums. At planting time, head back the one year old trees to 18 to 24 inches. Two or three weeks after planting, remove all the shoots except for those to be saved for scaffold branches. If the trees planted already have branches, select scaffold branches as described below.
Scaffold branches should be well placed on all sides of the trunk and as near as possible to the place where the tree was cut back at planting. Two weeks after selecting scaffold branches, inspect the trees and remove any shoots that have formed. In the spring of the second year, remove any shoots that will not be used as scaffold branches. Cut the scaffold branches back to equal lengths.
Mature trees should not be pruned heavily. There should be about 10 inches of growth per year on bearing trees. If the terminal growth gets much shorter a good thinning out is called for. Light annual pruning is preferred over heavier less frequent pruning.
Plums may bear crops which are too large causing the branches to break. Another disadvantage of a heavy crop is that brown rot will be worse when the fruits are crowded. If a heavy crop is set it can be thinned after the June drop.