Plum trees, including the European plum (Prunus domestica) and the Japanese plum (Prunus salicina), are popular fruit-bearing additions to home gardens and commercial orchards. Establishing the correct planting distance is the primary consideration for long-term success. Proper spacing ensures adequate sunlight penetration, which is necessary for fruit development and canopy health. Maximized air circulation minimizes humidity around the leaves and branches, significantly reducing the risk of common fungal diseases. Giving a plum tree room to mature allows it to reach its maximum productive potential and results in a more abundant fruit yield.
Understanding Rootstock and Tree Size
The final, mature size of a plum tree is determined by the rootstock onto which the desired plum variety has been grafted, not the variety itself. Rootstock is the root system and base trunk section that controls the tree’s vigor and overall growth habit. This underlying structure is the single most important factor dictating the required space between trees.
Plum rootstocks are divided into three major size categories, each with a distinct footprint. The smallest is the Dwarf rootstock, such as ‘Pixy’, which produces trees that mature to a height and spread of 8 to 10 feet. Semi-Dwarf rootstocks, like ‘St. Julien A’, are widely used by home gardeners, resulting in medium-sized trees that reach 12 to 17 feet. These trees offer a good balance of manageable size and high productivity.
The largest category includes Standard rootstocks, which produce the most vigorous growth and were historically used in traditional orchards. Trees on these rootstocks can easily exceed 20 feet in height and width. Although they take longer to begin fruiting, these large trees offer the greatest overall long-term yield. Selecting the appropriate rootstock based on available space is the first step toward successful cultivation.
Conventional Spacing Measurements
The conventional spacing guidelines provide the necessary minimum distances for plum trees planted in a typical, free-standing orchard or backyard setting. These measurements prevent mature canopies from overlapping, ensuring sufficient light exposure and air movement. The distance is measured from the center of one tree trunk to the center of the next.
Dwarf plum trees, which reach 8 to 10 feet in height and spread, require a minimum spacing of 8 to 12 feet. This tight spacing makes them ideal for smaller yards or container growing. Semi-Dwarf varieties, which grow to 12 to 17 feet, need 15 to 20 feet between trunks to accommodate their wider spread. This range allows the semi-dwarf tree to develop a full, open-canopy structure.
Standard plum trees, which can reach 20 to 25 feet or more, require the most substantial spacing. These large trees should be planted 20 to 25 feet apart to allow their extensive root systems and broad canopies room to develop fully. When planting in multiple rows, the distance between rows should be slightly greater than the distance between trees within the row. This extra space, often 3 to 5 feet, allows for maintenance access and maximizes light penetration to the lower branches.
Adjusting Spacing for High-Density Planting
For growers with limited space or those aiming for intensive commercial production, planting distances can be dramatically reduced using high-density techniques. These methods intentionally violate conventional spacing rules by relying on dwarfing rootstocks and rigorous, annual pruning to manage tree size. This approach allows a greater number of varieties to be grown in a small area, sometimes referred to as Backyard Orchard Culture.
One high-density method involves planting trees in a narrow, structural arrangement, such as an espalier, where branches are trained flat against a wall or trellis. This two-dimensional system permits very tight spacing, often allowing trees to be placed as close as 5 to 8 feet apart. Planting trees to form a plum hedge or fence can also be accomplished by setting semi-dwarf trees closer, sometimes 6 to 10 feet apart, and maintaining a narrow profile through aggressive summer pruning.
A common backyard technique is planting multiple dwarf or semi-dwarf trees in a single hole or very close together, typically 18 to 48 inches apart. This creates a multi-grafted appearance, with each tree variety acting as a separate leader within a single planting spot. While this maximizes variety and staggers the harvest period, it requires a high commitment to summer pruning to restrict vegetative growth and prevent shading.