Plum trees are a rewarding addition to many gardens, offering beautiful blossoms and delicious fruit. Understanding their root systems is important for successful planting and long-term tree health. The roots play a role in anchoring the tree, absorbing water, and taking up essential nutrients from the soil. A good understanding of how these roots grow and behave helps ensure the tree thrives and avoids potential issues with nearby structures.
Understanding Plum Tree Root Systems
Plum trees develop a fibrous root system, a network of many fine roots spreading out rather than a single, dominant taproot. This network consists of both structural roots, which provide stability and anchor the tree, and fine feeder roots, primarily responsible for absorbing water and dissolved nutrients from the soil. These feeder roots are generally located closer to the soil surface.
The overall size and characteristics of a plum tree’s root system are significantly influenced by its rootstock. Most fruit trees are grafted onto a rootstock, chosen for its specific root properties. Rootstocks can impart qualities such as dwarfing, semi-dwarfing, or vigorous growth, directly affecting the mature size of the tree and, consequently, the extent of its root system. For instance, a dwarfing rootstock like Pixy will result in a smaller tree with a more compact root system, while a semi-vigorous one like St. Julien A supports a larger tree.
Plum Tree Root Depth and Spread
Plum tree roots exhibit a spreading and relatively shallow growth pattern. The majority of active feeder roots are concentrated within the top 18 to 24 inches (45-60 cm) of soil, where oxygen and nutrients are readily available. While some larger structural roots can extend deeper, particularly in well-drained soil, their primary function is anchorage rather than nutrient uptake.
The lateral spread of plum tree roots can be extensive, often reaching one to two times the diameter of the tree’s canopy, extending significantly beyond the tree’s drip line. Factors such as soil type, water availability, and the chosen rootstock influence this spread. Roots tend to grow deeper in loose, well-drained soils, while compacted or waterlogged conditions can lead to shallower, more widespread root growth. Consistent, deep watering encourages roots to grow further down, promoting stability and drought tolerance.
Potential Issues with Plum Tree Roots
While plum trees are not typically considered highly invasive, their roots can present challenges if planted too close to certain structures. The spreading nature of their root system, especially surface roots, can potentially lift or crack sidewalks, driveways, and patios over time as the tree matures and its roots expand.
Plum tree roots can also infiltrate and clog older, leaky underground pipes, such as sewer or water lines, particularly if these pipes have existing cracks or loose joints, as roots are naturally drawn to sources of water and nutrients. However, healthy, intact plumbing systems are generally not at significant risk from tree roots.
Another common characteristic of plum trees, especially those on certain rootstocks or if the roots are damaged, is suckering – new shoots that emerge directly from the root system, often appearing some distance from the main trunk. These suckers can become a maintenance concern and, if left unchecked, can divert energy from the main tree. Plum roots can also compete with nearby plants for water and nutrients, potentially affecting the growth of surrounding garden beds.
Managing Plum Tree Roots
Thoughtful planning reduces potential plum tree root issues. Selecting an appropriate planting location is paramount, ensuring sufficient distance from buildings, foundations, sidewalks, and utility lines. Plant plum trees at least 8 to 10 feet away from such structures, though the exact distance can vary based on the tree’s mature size and rootstock.
Choosing the right rootstock is a key management strategy. Dwarfing or semi-dwarfing rootstocks (e.g., Pixy, VVA-1) result in smaller trees with less extensive root systems, making them suitable for more confined spaces. Conversely, vigorous rootstocks (e.g., Brompton) will produce larger trees requiring more space. Understand the mature size of the chosen rootstock to select a tree that fits the available area.
For existing trees or in situations where root encroachment is a concern, physical root barriers can be considered. These barriers, often made of plastic or specialized fabric, are installed in the soil to deflect root growth away from sensitive areas. While they can be effective, proper installation is important to prevent girdling the tree or creating other root problems. Additionally, deep and infrequent watering encourages roots to grow downwards, promoting a more stable and less problematic root system than shallow, frequent watering. Root pruning can be used in specific situations to manage root growth, but it should be done carefully by a professional to avoid harming the tree’s health or stability.