Plums need soil with a pH of 6.0 to 8.0. Buy standard trees 3 to 6 feet tall, and dwarf trees 3 to 4 feet tall. Japanese and Japanese-American hybrids begin to bear two to four years after planting; European and damson plums begin to bear three to five years after planting. In Zones 4 and 5, plant plum trees in early spring as soon as the ground can be worked; they should be planted during the fall or winter.
Cut off all but three or four of the strongest branches that are spaced 6 to 12 inches apart; make sure they spread in different directions and form angles greater than 45 degrees with the trunk.
Cut them back to 6- to 8-inch stubs. Each year thereafter prune the dormant trees only to thin overcrowded or crossing branches or to remove deadwood or the erect fast-growing shoots called water sprouts that appear along the trunk or branches. When pruning, be sure to remove any stems that have black swellings, called black knot. Make cuts at least 6 inches beyond any apparent injury.
In the Northwest, where maximum summer daytime temperatures average less than 90 and cloudiness and mist are common, recommended varieties are Beefeater, indeterminate, 75 days, VFN; Terrific, indeterminate, 70 days, VFN; and Vineripe, indeterminate, 80 days, VFN. In the Southwest, where the climate is arid and maximum summer daytime temperatures average over 90, recommended varieties are Beefeater, indeterminate, 75 days, VFN; Better Boy, indeterminate, 70 days, VFN; and Spring Giant, semideterminate, 65 days, VF.
In the South, where summers are long and hot, and maximum summer daytime temperatures average over 90, recommended varieties are Better Boy, indeterminate, 70 days, VFN: Manalucie, indeterminate, 82 days, F; and Tropic, indeterminate, 82 days, VF.
For cooking purposes pick plums when they become covered with a waxy white coating called bloom and are firm but springy to the touch. For eating fresh or for drying, pick them when they become soft and fully ripe and are easily twisted off.
