Culture
Best grown in moist, moderately fertile, well-drained loams in full sun. Tolerates light shade, but best flowering is in full sun. Prune after flowering if necessary but generally requires little pruning.
Needs another variety for pollination.
Noteworthy Characteristics
Prunus is a genus of about 200 species of deciduous and evergreen trees and shrubs found in north temperate areas, the Andes of South America and in mountainous areas of Southeast Asia. Some are grown for their showy flowers, colorful foliage and/or attractive bark; and others for fruit, which includes cherry, plum, apricot, nectarine and peach.
Genus name from Latin means plum or cherry tree.
'Johnson' is a plum selection sold under the trade name of STARKING DELICIOUS. It was discovered as a chance seedling and has unknown parentage, though it shares fruiting and pollination characteristics with Japanese/Asian plum cultivars. This selection is typically grafted to one of several different rootstocks which can control the size of the tree (tree height in parenthesis): standard (15-20'), semi-dwarf (12-15') and dwarf (8-10'). White flowers appear in early spring followed by clingstone plums which feature red skins and red flesh, and which ripen in late summer. Trees usually will begin to bear fruit in 3-4 years. US patent PP1064 applies to this plant.
Problems
Susceptible to a large number of insect and disease pests. Potential diseases include leaf spot, die back, leaf curl, powdery mildew, root rot and fireblight. Potential insects include aphids, scale, borers, leafhoppers, caterpillars, tent caterpillars and Japanese beetles. Spider mites may also be troublesome.
Uses
Large, sweet plums with tasty, firm flesh are excellent for fresh eating. This selection can also serve as a pollinator for certain other Japanese/Asian plum cultivars. Plants with dwarf rootstocks are good for smaller spaces.