Cedar trees are common in many landscapes, valued for their distinctive appearance and often their pleasant fragrance. Understanding their root systems is important for anyone planting or managing these trees. The characteristics of cedar roots, including their depth and spread, influence how they interact with the surrounding environment and nearby structures. Proper knowledge of these root systems can help in making informed decisions about tree placement and care, ensuring both tree health and property integrity.
Understanding Cedar Root Systems
The term “cedar” applies broadly to various coniferous trees, leading to common misunderstandings about their root structures. True cedars (Cedrus genus) include species like Atlas cedar (Cedrus atlantica) and Deodar cedar (Cedrus deodara). These true cedars often develop a deep taproot when young, which helps anchor them, along with an expanding system of lateral roots.
Many trees commonly called “cedars” are, in fact, not true cedars but belong to different genera, such as Thuja, Juniperus, and Chamaecyparis. For instance, the Eastern red cedar (Juniperus virginiana) and Western red cedar (Thuja plicata) are well-known examples. These “false cedars” typically feature more fibrous, shallow root systems that spread widely rather than developing a prominent taproot.
Cedar Root Depth and Spread
The actual dimensions of cedar root systems vary considerably depending on the specific species and growing conditions. For true cedars, like the Atlas cedar, the taproot can extend several feet deep in well-drained soils, providing strong anchorage. Their lateral roots can spread horizontally, often extending beyond the tree’s drip line, which is the area directly beneath the outer circumference of the tree’s canopy.
Many “false cedars,” such as Thuja species (e.g., ‘Emerald Green’ arborvitae), typically have shallow, fibrous root systems. These roots primarily occupy the top 12 to 24 inches of soil, but can spread extensively, often two to three times the canopy width. Soil composition, moisture availability, and tree age significantly influence both root depth and lateral reach. Compacted or poorly drained soils can restrict root penetration, causing them to spread more superficially.
Mitigating Potential Root Damage
Cedar roots, especially from larger, mature trees, can pose risks to nearby structures if not managed. Their expansive, shallow root systems can exert pressure on foundations, leading to cracks. Sidewalks, driveways, and patios are also susceptible to lifting and cracking as roots grow and expand beneath them. Underground pipes, especially older or compromised ones, can be infiltrated by fine root hairs seeking moisture, leading to blockages or leaks.
To prevent issues, proper planting distance is important. For species with extensive root systems, planting 15 to 20 feet from structures is recommended to allow adequate root development. Where space is limited, installing a root barrier can be considered. These barriers, typically high-density plastic or specialized fabric, are installed vertically to deflect root growth away from structures. Consulting a certified arborist can help determine the most effective mitigation strategy for specific site conditions and tree types.
Maintaining Healthy Cedar Roots
Nurturing a cedar tree’s root system promotes its overall health. Consistent watering, especially during dry periods, ensures roots have adequate moisture without becoming waterlogged. Young trees benefit from regular deep watering to encourage robust root development. Applying organic mulch (e.g., wood chips, shredded bark) around the tree’s base helps retain soil moisture and regulate temperature.
Mulch also suppresses weeds, reduces competition for water and nutrients, and enriches soil as it decomposes. Avoiding soil compaction over the root zone is important, as compacted soil restricts oxygen and water penetration, hindering root function. Avoid parking vehicles or heavy foot traffic directly over the root zone. If root pruning is necessary, it should only be performed by qualified professionals who understand the tree’s physiology and can execute the procedure safely without causing long-term damage.