To care for a Santa Rosa plum tree, plant the tree in a location with well-draining soil and full sun, and water the tree once weekly. Prune the tree during winter, and apply fertilizer at the beginning of spring. Treat the tree for disease and pests as needed. To help prevent pests and disease, remove fallen fruits and dead leaves from the base of the tree on a regular basis.
When planting young trees, choose a location away from the home or other buildings to prevent frost damage, and water the tree deeply each week. Provide more water when the weather is hot and dry. Santa Rosa plum trees are susceptible to disease, such as leaf scald. Examine the leaf, trunk and fruit on a regular basis, and provide the recommended treatment immediately.
During the first year, prune the tree to shape it. Afterward, prune away dead or diseased branches, and prune away competing branches and unwanted new growth.
When planting more than one tree, space the trees 12 to 15 feet apart. Harvest the plums after three to five years of growth. The plums are ripe when the fruit is slightly soft. White spots on the fruit is an indication the fruits are ripe.