Growing Olea europaea, the olive tree, in a container is a popular method, especially in climates where it cannot survive winter outdoors. This container method allows for mobility, enabling the tree to be moved indoors during cold periods. The fundamental principle governing the tree’s height in a pot is the restriction of its root system, which naturally dwarfs the above-ground growth compared to those planted directly in the soil.
Understanding Expected Container Height
The maximum height an olive tree reaches in a pot is significantly less than its potential height when planted in the ground. While inground olive trees can reach 20 to 30 feet, potted specimens are typically restricted to a manageable range of 4 to 8 feet. This height depends on the variety selected and the maintenance regimen applied. The size of the root ball dictates the size of the tree’s canopy. This restricted growth is a direct physiological response to the limited volume of the container, which prevents the extensive root growth necessary to support a large canopy. The final height is largely determined by the grower’s active management through pruning and pot selection.
The Influence of Variety and Container Size
Variety Selection
Selecting the right cultivar is the first step in controlling the final size of a potted olive tree. Standard varieties like ‘Mission’ or ‘Manzanillo’ are naturally vigorous and may attempt to reach 10 to 15 feet even in a large container. Dwarf and semi-dwarf varieties possess a genetic predisposition for smaller growth, making them easier to manage. Cultivars such as ‘Little Ollie’ (Olea europaea ‘Montra’) are true dwarfs, typically reaching only 3 to 6 feet in a pot, while semi-dwarf types like ‘Arbequina’ and ‘Koroneiki’ can be maintained around 6 to 8 feet.
Container Size and Potting Strategy
The container’s physical size imposes a definitive constraint on the tree’s development. The volume of the pot directly influences the size of the root ball, which limits the height and breadth of the canopy. For a mature, 6-foot tree, a pot that is approximately 2 feet deep and 2 feet wide is often considered suitable. Starting a young tree in a pot that is too large can lead to water retention issues. A strategy of “potting up” gradually, moving the tree to a slightly larger container every few years, is often preferred. The ultimate goal is to match the pot size to the desired final canopy size, as restricting the root system is the primary mechanism of dwarfing.
Essential Techniques for Size Management
Canopy Pruning
Active intervention through pruning is necessary to maintain a fixed, ornamental height and shape for a potted olive tree. Canopy pruning should be performed annually in late winter or early spring, just before the tree enters its active growth phase. To directly reduce height, a heading cut is used, which involves shortening the main branches back to an outward-facing bud or a lateral branch. This cut removes the terminal growth and encourages denser, bushier growth lower down, rather than vertical extension. Thinning cuts are applied by removing entire branches that are growing inward or crossing others, which improves air circulation and light penetration.
Root Pruning and Repotting
Maintaining an open, vase-like shape is a common goal, as it allows light to reach the lower branches and helps prevent disease. For long-term height control, the roots also require regular maintenance. To keep the tree in the same size pot indefinitely, root pruning and repotting are required every two to three years. During this process, the tree is carefully removed, and the outer third of the coiled root mass is trimmed away using sharp tools. This procedure prevents the tree from becoming root-bound, maintains the root-to-shoot ratio, and requires replanting in the same container with fresh, well-draining potting mix.