Laurel plants are a popular choice for many gardens, known for their evergreen foliage and dense growth. The term “laurel” encompasses several distinct species, each with unique growth habits and root systems. Understanding these root characteristics is important for successful cultivation and to protect surrounding property.
Understanding Laurel Root Systems
The diverse group of plants commonly called “laurel” includes species such as Cherry Laurel (Prunus laurocerasus), Bay Laurel (Laurus nobilis), and Mountain Laurel (Kalmia latifolia), each with distinct root systems. Cherry Laurel, for instance, develops a large, fibrous root system that spreads widely. These roots extend horizontally, sometimes reaching 3 to 4 feet, and are particularly effective at absorbing soil moisture.
Bay Laurel features an extensive and vigorous fibrous root system. While young plants may have shallower roots, mature Bay Laurels develop a widely spreading network requiring ample space. This aggressive habit allows the plant to seek out water and nutrients effectively.
In contrast, Mountain Laurel typically forms a shallow root system. This shallow nature makes them less prone to causing issues with nearby structures.
Potential Concerns with Laurel Roots
Laurel roots can present several challenges for gardeners and property owners due to their expansive growth and resource needs. Cherry Laurel, in particular, is recognized for its competitive roots and can be invasive in certain environments. Its vigorous growth and ability to rapidly spread can out-compete native plants.
Bay Laurel, while not classified as invasive like Cherry Laurels, can still exhibit aggressive root growth. Its extensive underground network can occupy significant soil space, depriving nearby plants of water and nutrients. This competition can hinder the growth of surrounding flowers, shrubs, or turf.
Many laurel species can cause structural damage. The fibrous roots of Cherry Laurel can draw moisture from the soil, leading to soil contraction. This drying effect can cause shifts in building foundations, pathways, and driveways. Similarly, the widely spreading roots of Bay Laurel can exploit existing cracks or weaknesses in foundations, plumbing, or sewer lines. Roots do not actively “seek” out pipes but proliferate where conditions, such as leaks, provide water and oxygen.
Mitigation and Management Strategies
Proactive planning and management can reduce problems with laurel roots. When planting, maintain distance from structures. For Cherry Laurel, planting at least 2 to 3 meters (approximately 6.5 to 10 feet) away from buildings is recommended. Bay Laurel should also be kept 5 to 10 feet from homes and underground utilities.
Root barriers offer a means to redirect root growth away from vulnerable areas. These barriers are typically made of heavy-duty plastic sheeting, installed vertically in the soil. The barrier forces roots to grow deeper or in a different direction, preventing them from impacting foundations or pipes. When installing, ensure the barrier extends deep enough (12 to 48 inches) and that the side facing the tree has a crease to guide roots downwards.
Above-ground pruning can influence root development, as the plant’s root system generally mirrors its canopy size. Regular pruning of foliage and branches can help limit the growth and spread of the root system. Selecting appropriate laurel species for the planting site, considering mature size and root characteristics, is another effective preventative measure. For example, Mountain Laurel, with its typically shallow and non-invasive root system, may be a better choice for areas closer to structures compared to Cherry Laurel.
Laurel Root Removal
When a laurel plant’s roots become problematic, several removal methods can be employed. Manual removal involves digging out the stump and most of the root system. This process can be labor-intensive, especially for mature plants with extensive root networks, and often requires tools like mattocks and shovels.
Chemical treatments can also be used to kill laurel roots and prevent regrowth. Herbicides are effective when applied directly to freshly cut stumps. The herbicide is absorbed by the cambium layer, which then transports the chemical to the roots, leading to their demise. High-nitrogen fertilizers or stump removers, such as potassium nitrate, can also be drilled into stumps to accelerate root decay, though this method is slower.
For larger or more established laurel plants, professional services may be necessary, using specialized equipment like stump grinders to remove the main stump and surface roots efficiently. When removing Cherry Laurel, manage all plant parts carefully, as cut branches and stems can root and sprout new growth. Proper disposal of all plant material prevents unintended propagation.