Arborvitae are a popular choice for many landscapes, valued for their dense foliage and ability to form privacy screens or hedges. A common question arises regarding their root systems and whether they pose a risk to nearby structures. Understanding the characteristics of arborvitae roots is important for proper planting and long-term care. This article provides clarity on the nature of arborvitae roots and offers practical advice for managing them.
Understanding Arborvitae Root Systems
Arborvitae develop a fibrous and shallow root system, rather than a deep taproot. These roots spread out horizontally, creating a dense network that anchors the plant and absorbs moisture and nutrients from the upper soil layers. Arborvitae roots grow to about 12 to 18 inches deep, though larger varieties can reach 18 to 24 inches.
The lateral spread of these roots can reach a width equal to or even 1.5 times the height of the tree. For instance, a 10-foot-tall arborvitae could have roots spreading 10 to 15 feet from its trunk. Despite their wide spread and density, these root systems are not considered aggressive or destructive to sound structures.
Are Arborvitae Roots Truly Invasive?
Arborvitae roots are not considered invasive in the sense of damaging robust foundations or plumbing. Unlike some other tree species with aggressive root habits, arborvitae roots do not possess the force to crack solid concrete or pipes. Roots exploit existing weaknesses, such as pre-existing cracks or loose joints, where they can find moisture and oxygen.
If a pipe has a leak or a foundation has a hairline fracture, arborvitae roots, like those of many plants, can grow into these openings in search of water. This behavior is a general plant characteristic driven by the need for resources, not a unique invasive quality of arborvitae. Ensuring that structures and utilities are in good repair minimizes the likelihood of roots entering them.
Preventing Root-Related Issues
Proper planting is key to preventing root-related issues with arborvitae. Keep them at least 3 to 5 feet away from house foundations. For septic systems and underground utilities, distances can range from 10 feet to even 25-70 feet, depending on local guidelines and the specific utility. This spacing allows roots ample room to develop without directly interacting with infrastructure.
Soil preparation also supports healthy root development. Arborvitae thrive in well-drained soil rich in organic matter. Amending the soil with compost can improve drainage in clay soils and enhance moisture retention in sandy soils. Consistent, deep watering encourages roots to grow downward rather than spreading shallowly in search of surface moisture. Applying a 2-3 inch layer of mulch around the base helps retain soil moisture, regulate temperature, and discourage shallow surface root growth.
Addressing Existing Root Concerns
If concerns arise regarding established arborvitae roots, accurately assessing the situation is important. Distinguishing between perceived issues and actual structural damage is important. Signs of damage include changes in a tree’s lean or visible cracks in nearby structures that coincide with root presence. For professional evaluation and tailored solutions, consult a certified arborist or a landscape professional.
An arborist can assess root health and potential risks, offering advice on interventions. Root barriers are an option, though their effectiveness varies and they require proper installation. These barriers are installed underground to redirect root growth away from sensitive areas. Selective root pruning is another option for managing problematic roots, best performed during the dormant season. However, this should only be done by a professional, as removing more than 10-20% of the root mass or cutting into old wood can stress or harm the tree.