Apricot trees (Prunus armeniaca) are popular backyard fruit producers, but their mature size varies significantly based on the rootstock they are grafted onto and the specific cultivation methods employed. The ultimate height and spread a tree can achieve is largely determined at the time of planting. Understanding the interaction between this inherent potential and external conditions allows a gardener to successfully manage the tree and select one appropriate for their available space.
The Range of Mature Sizes
The final size of an apricot tree is primarily dictated by the rootstock, which is the root system onto which the desired apricot variety is grafted. This rootstock acts as a genetic brake, controlling the vigor of the tree. Apricots are generally categorized into three size classes based on this control mechanism.
Standard, or full-sized, apricot trees are typically grown on their own roots or a vigorous seedling rootstock, allowing them to reach their maximum genetic potential. These large trees generally mature to a height and spread of 15 to 25 feet, often requiring significant space in the landscape. Standard trees tend to be the most vigorous and longest-lived, but their size makes maintenance and harvesting considerably more challenging.
Semi-dwarf trees are the most common choice for home orchards, as they offer a good balance of manageable size and high fruit yield. These trees are grafted onto semi-vigorous rootstocks, such as ‘St Julian A’ or ‘Citation,’ which reduce the tree’s overall height by about 25 to 50 percent compared to a standard tree. A mature semi-dwarf apricot will typically reach between 10 and 15 feet tall with a similar spread, often allowing most fruit to be harvested without a tall ladder.
Dwarf apricot trees are the smallest option, usually maturing at heights between 6 and 10 feet. These are either naturally genetic dwarfs or are grafted onto highly dwarfing rootstocks like ‘Krymsk 1.’ Their reduced size makes them ideal for small spaces, container growing, or intensive planting systems, though they may require staking for support in their early years.
Environmental Factors Influencing Growth
While the rootstock sets the genetic limit, environmental factors determine whether an apricot tree actually reaches its potential size. Optimal growth requires full sun, meaning the tree must receive a minimum of six to eight hours of direct sunlight daily. Insufficient sunlight causes the tree to produce sparse, elongated branches, resulting in a weak, less robust structure.
The quality of the soil is another limiting factor, as apricot trees require deep, fertile, and well-drained conditions. Planting in heavy clay or poorly drained soil can lead to root rot and subsequent decline in vigor, significantly stunting the tree’s growth regardless of its genetic size class. The soil pH should ideally fall between 6.0 and 7.5 for optimal nutrient uptake and growth.
Apricots need consistent moisture, especially during the active growing season, to support structural development. Prolonged drought restricts the tree’s overall growth as it conserves energy, preventing it from reaching its mature height. Apricot trees also require a specific number of winter chill hours (periods between 32°F and 45°F) to properly break dormancy and initiate healthy spring growth. A lack of sufficient chill hours stresses the tree, leading to poor flowering and reduced vegetative vigor.
Controlling Size Through Pruning and Training
For the home gardener, the most direct way to control the ultimate size of an apricot tree is through intentional pruning and training. This intervention can maintain even a standard-sized variety at a much smaller, more manageable height.
Structural pruning is traditionally performed during the dormant season, typically in late winter or early spring before new growth begins. This involves thinning cuts to remove crossing, damaged, or inward-growing branches, establishing a strong, open framework, such as the open vase or goblet shape. Removing large limbs actively reduces the tree’s overall size and prevents the canopy from becoming too dense.
To restrict height and spread during the active growing season, summer pruning is used, which is best done immediately following the harvest. This technique involves making heading cuts, or “tipping,” to shorten the tips of new vegetative growth. Removing this growth shifts the tree’s energy away from increasing height and redirects it toward developing fruiting spurs for the following year.
Gardeners with limited space can utilize specialized training systems to keep trees manageable. While apricots are often too vigorous for true espalier, they respond well to fan training against a sunny wall or fence. This method flattens the tree into a two-dimensional plane, severely restricting its volume and allowing semi-dwarf varieties to be maintained at heights as low as six feet.