You’ve spent time - and likely, money - planning the perfect hardscape. Sidewalks are in place and curbing poured. You might have even invested money into infrastructure—irrigation and lighting systems diligently installed and working well. Then, there is the completed design of your landscape including plants, bushes, flowers and… trees.
One of the most challenging aspects of this process are strategizing for the trees that are integrated into overall plan. Primarily, because trees have large root systems that as they grow, can lift up or disrupt sidewalk and curb design or even invade other parts of your installed infrastructure, such as septic, irrigation, and/or lighting systems. Unchecked tree roots can also break through and uproot your carefully-designed landscape elements.
While it’s hard to totally eliminate this risk, there are solutions that - with careful pre-planning - can dramatically reduce the risk of damage to your hardscape and infrastructure from unwieldy and uncontrolled tree root growth.
How Do Tree Roots Normally Grow?
Species of tree, climate zone, soil composition and water are just some of the elements effecting how tree roots will expand.
While you would think that most of the roots grow down into the soil, as the roots spread, some will also “reach for the sun.” This is especially true if something - such as the water table, infertile or harder soil, or rocks and other debris, hinder easy downward growth. In such cases, knowing how far the root system will actually spread - out and possibly up - can be hard to estimate.
In terms of trying to pinpoint root system growth distance in a width measurement, studies seem to vary but generally agree that the expanse of root systems can reach four to eight times past the drip line!
Now, maybe that has you thinking, “Wow… how can I structure my plans around tree growth when the experts can’t even agree where those roots will go and how wide an expanse they will grow to cover?” Well, that is one reason why unchecked or unmanaged tree root growth can be such a problem if you are trying to create an organized design in your hardscape and landscaped areas.
Generally, a project arborist will look at the trunk of a tree and its size to figure out how much space the tree root system should be assigned. This is called the “tree protection zone” and a basic rule is a one foot radius per inch of the tree trunk diameter. The ratio works out to be twelve to one (12:1). But again, this is basically an “educated guess” and the actual tree root growth span could wildly vary from this estimation due to the aforementioned factors and more.
What If My Plans Can’t Accommodate - or Could Be Ruined or Damaged By - the Natural Growth Pattern of Tree Roots?
Obviously, if you are planning a specific hardscape and landscape scheme either around or integrating trees, allowing for the natural growth pattern of the tree roots is just not likely going to work. This is where and why deep root barriers enter the equation.
A deep root barrier helps to manage and direct tree root growth to prevent the roots from expanding unchecked and breaking through the hardscape elements like sidewalks and curbs, infrastructure like irrigation and lighting, and your landscape components as well.
The good news is that if you’re considering the need for deep root barriers, you have several options and choices. From cloth-based or woven barriers (root traps and screens), to physical deep root barriers, and even woven/chemical combo barriers, there is likely something that will work for most projects.
Undoubtedly, we are partial to Sidewalk Shield. Planning and installing Sidewalk Shield can help avoid costly replacement of sidewalks, roads, driveways, septic systems, etc. Sidewalk Shield is specifically design to force tree roots downward. “Forcing” the downward growth of tree roots helps to prevent the upheaval of roads and sidewalks, as well as damage to infrastructure and landscape, by redirecting surface and lateral roots that undermine these structures.
You’ve very likely spent a lot of time and energy, as well as invested a bit of money, in your hardscape, infrastructure, and/or landscape plans. The time to stop short is not at pre-planning for tree root growth and expansion. Without wisely addressing this potential threat in advance, you could later find yourself in a deep (root) mess!