Santa Rosa plum is a Japanese variety popular for its prolific, juicy fruit. Whether you choose a dwarf variety, which grows only 8 or 10 feet tall, or a full-size tree, expect a bountiful harvest of large, dark-colored plums in the summer. Like the other stone fruits, the Santa Rosa plum needs a certain amount of cold weather, making it perfect for gardens in USDA climate zones 5 through 9. This tree is self-fruitful, so get ready to make some jam in three years.
Plant a dwarf Santa Rosa plum in fertile, well-drained soil. Add about 2 gallons of gypsum to the planting hole to help with drainage. Spread a ring of compost around the base of the tree to help conserve soil moisture, keep weeds away and nourish the tree.
Train the tree to a central leader when it is small by pruning lower branches back to the main trunk without cutting into the trunk. If you prefer an open center, prune the top branches back to the trunk. Prune the tree in late summer after it has produced fruit.
Fertilize the tree once each year in late spring with a balanced plant food, such as one having an N-P-K ratio of 10-10-10. An annual feeding of potash and lime also is helpful. Follow the instructions on the fertilizer package for best results.
Spray the tree with insecticidal soap if ants are present. Ants don’t harm the tree, but they bring insects such as aphids that cause damage. Smear a ½-inch-thick ring of Tanglefoot around the lower trunk of the tree to prevent ants from climbing into the branches.