Adaptable to different soils and climates, two main categories of edible plum trees, European (Prunus domestica) and Japanese (P. salicina), prosper at the western U.S. Both bloom in late winter or early spring. Fruit ripens sometime between May and September, depending on the cultivar and the weather. Expect Japanese plums to bloom and achieve harvest earlier. Maturity takes roughly 140 to 170 days for both types of plums.
Fruit Differences
Plums of all kinds are available in many colors, inside and outside. The range of skin colors contains yellow, red, purple, green, blue and almost black, while the flesh could be red, yellow or green. In general, the fat, juicy red ones are Japanese, although European types would be the smaller, purple, blue or purple fruits. But two old standard European plums, “Green Gage” and “Mirabelle,” are yellow and green, respectively. Prunes, a plum variety with sugar content high enough to enable sun-drying without causing fermentation, fall under the European group. European plums, which have firmer flesh, are often canned or made into jams or jellies, while Japanese plums are nearly always eaten fresh.
Pollination
Japanese plum trees are more prone than European varieties to require cross-pollination. Though most European plums are self-fertile, you may produce a better crop if you develop two or more varieties together, so long as they’re in precisely the same color group. “Santa Rosa,” a self-fruitful Japanese cultivar, is reputed to increase the yield of any other Japanese variety when both cross-pollinate. No one European variety is preferred over another as a pollinator.
Pruning and Training
In the orchard, both European and Japanese plum trees can reach 15 to 20 feet, with a slightly bigger spread. Pruning keeps them to about 10 feet in both directions. No truly dwarfing rootstocks exist for plums. Mature Japanese plum trees require more extensive pruning, cutting back side shoots to stop crowding compared to their European counterparts. Normally, Japanese plums are trained to a vase shape. When fruit types, the little plums must be thinned to you every 4 to 6 inches or so the fruit’s weight might break branches. Training a European plum tree to a single leader usually works best.
Outstanding Varieties of Each
“Coe’s Golden Drop,” a golden-fleshed plum having an intense apricot-like flavor and “Damson,” which has purplish-black green and skin flesh and excels in jam and jelly, are notable European plums. “French Prune,” the standard drying prune of California, and “Stanley,” sweet and hot and good for canning, stand from European prune varieties. All thrive in U.S. Department of Agriculture plant hardiness zones 5 to 9. One of the most flavorful Japanese plums are “Autumn Rosa,” a late-season plum with purplish-red skin, “Burgundy,” with dark red flesh and skin and “Santa Rosa,” a significant commercial variety for fresh eating. Each grows in USDA plant hardiness zones 7 to 10.