All trees have roots, but they are often something a homeowner doesn’t have to think about because they are hidden underground. But what about when roots appear above ground? It’s a problem we see often throughout Fairfield County and is more than just an eyesore. Exposed tree roots are a tripping hazard, they’re easily damaged (making them an easy access point for diseases and insects), and they frequently ruin lawn and landscape equipment. So, what can you do to fix exposed tree roots?
In this article, we cover:
- what causes exposed tree roots,
- how exposed tree roots can lead to larger issues,
- what you can do about exposed tree roots,
- what you should avoid when dealing with exposed tree roots,
- and more!
How Tree Roots Grow
A tree’s roots are its lifeline, even if those roots are growing above ground. Roots seek out water and nutrients from the soil to support tree growth. Wherever they find these, trees will send roots growing in that direction.
Many people are surprised to learn that most tree roots grow only in the top 4” to 20” of soil. That’s where there are enough oxygen, moisture, and nutrients to support the tree. And, although a tree’s drip line (the edges of its leafy canopy) is usually considered the edge of a tree’s root zone, a tree’s root system often spreads far wider.
The bottom line is that you can’t expect a tree’s roots to stay within a confined area or to grow only downward.
Why Tree Roots Grow Above Ground
Exposed tree roots happen for several reasons.
- Environmental conditions. Over time, rain falling on bare soil will compact it. This creates a crust that doesn’t absorb water, leading to water runoff instead of soaking down to where roots (should) grow. Rain will also erode and wash away bare soil, leaving roots exposed. And the soil in windy locations will often be scoured away from around tree roots.
- Too little space for roots. When trees are planted in small areas, their roots don’t have enough room to expand naturally. In an attempt to find water and nutrients, the roots will grow out of the soil and spread along the surface.
- Impervious surfaces surrounding the tree. When the areas surrounding a tree are made of concrete or other impervious materials (such as in a planting pit), roots won’t find oxygen and water beneath them. Additionally, the soil beneath sidewalks, roads, driveways, and foundations is heavily machine compacted, making it difficult for roots to grow.
- Heavy traffic areas. If a tree’s roots are growing in areas that are used by both pedestrians and vehicles, surface soil will wear away and become compacted from use. Any roots that were growing near the surface will become exposed as the soil around them wears away.
- Soil compaction. Whether the soil is compacted from rain falling on it, from vehicles driving and parking on it, or from construction, it creates conditions that are difficult for roots to grow in. When roots can’t grow down through dense soil, they grow at the surface where it’s easier to find oxygen and water.
- Tree species. Exposed roots are common in some species of trees. Often, shallow root development is the result of a tree having evolved in moist or wet growing conditions. Below are three common examples:
- Maples (Acer) naturally develop dense, shallow, fibrous root systems. These help the trees find water and nutrients in shallow and rocky soils.
- Poplars (Populus) are tall trees that develop extensive, spreading root systems. They often grow near water sources and so tend to have shallow roots. New poplars sprout from existing root suckers near the soil surface.
- Willows (Salix) grow in wet areas and have aggressive and extensive root systems. When planted in the right place, such as near waterways, these roots help stabilize stream banks by holding the soil together.
- Tree age. As a tree matures and grows, its root system is also spreading in an effort to find water and soil nutrients to support the growing tree. As these roots grow and age, they expand in diameter and become tough and woody. A small root growing near the surface will break the soil’s surface as it becomes thicker. If the soil around tree roots is eroding or becoming compacted, the root will break the soil surface sooner.
Why Exposed Tree Roots Are a Problem
- Tree roots are easily damaged. For example, foot traffic, vehicles driving over or parking on roots, and mowers and string trimmers can all damage roots. When roots are injured, they can no longer do their job of transporting water and nutrients from the soil to all parts of the tree. This stresses the tree and can lead to branch and leaf dieback.
- Damaged roots are vulnerable to diseases and insect pests. Like a bark wound, an injured root creates an opening for insects or diseases to get inside and damage a tree’s entire system. This can lead to expensive tree problems for a homeowner, including tree removal.
- Exposed tree roots can also cause damage! Garden tools can be damaged by protruding roots, and exposed roots can also become a tripping hazard to pedestrians. It can take less than an inch of root sticking out from the soil to trip someone who’s walking.
How to Deal with Exposed Tree Roots
First, understand WHY the roots are growing above ground. It may be due to an issue that you can fix but, almost as often, the cause isn’t something you can change. In those cases, it may be best to simply remove the tree if the exposed roots are a problem.
Next, learn what you can and cannot do to remedy issues with roots growing above ground. Doing the wrong thing can result in worse problems than just having an unsightly tripping hazard on your lawn!
What NOT to Do When Roots Grow Above Ground
- Bury roots with more soil. A tree that’s already growing should never have the soil level around its roots changed. Burying roots may hide them from your view but you’ll suffocate the roots, killing them and stressing your tree. When you kill roots, you’re cutting off the established lifeline of water and nutrients that the tree depends on.
- Pave over roots. Paving over exposed tree roots is like covering them with soil, only worse. If you pave over tree roots, those roots will die and decompose. As they do, they will make your paving base shift, causing the surface to become uneven and unstable. Now your paving will be a tripping hazard, too!
- Cut off tree roots. You should never cut exposed tree roots. Don’t be fooled by tough, woody roots that might look dead! They’re all alive and never go dormant. An exposed cut root is like a badly pruned branch; it can’t recover.
- Cover roots beneath a mulch volcano. Mulch is an important part of a healthy garden, but only when it’s in the right place. Never pile mulch up around the trunk to hide exposed roots (mulch volcanoes are a leading cause of tree death!). Always keep mulch away from the base of your tree’s trunk.
- Disguise exposed roots under a new planting bed. Keep any new planting areas at the tree’s drip line or beyond. Digging in the important root zone around a tree is extremely damaging and can kill the tree. Plus, adding new plants around an existing tree also creates more competition for water. You’ll have healthier trees that live longer if you plant annuals and perennials in separate areas and leave the soil around your tree undisturbed.
What You SHOULD Do With Exposed Roots
- Cover exposed roots with a layer of organic mulch. This is a good solution when the lawn is growing beneath a tree and struggling. A tidy, even circle of mulch beneath a tree’s crown is an easy way to resolve tree root and turfgrass conflict; mulch will protect roots and kill the grass. Just be sure to keep mulch pulled well back from the tree’s trunk.
- Fix compacted soil. Compacted soil is a major cause of both exposed tree roots and poor tree health. If you have compacted soil, have it repaired professionally. The best (and least damaging) way to improve compacted soil is to use an airspade around a tree’s roots to loosen the soil, incorporate compost to add nutrients, and then fill it back in. Ideally, you’d then spread a layer of wood chip mulch out to the drip line to eliminate future compaction. Or compromise with a mulch ring around the tree with grass seed (or sod) farther away.
NOTE: Many homeowners want to replace lawn beneath their trees after soil aeration. It’s important to remember that shallow lawn irrigation is a major cause of exposed tree roots, and that heavy lawn equipment like mowers both cause exposed tree roots and make them worse.
How to Prevent Roots From Growing Above Ground
People sometimes turn to root barriers as a way to stop roots from spreading above ground. However, root barriers are only a temporary fix. Root barriers may send some roots away from where they aren’t wanted, but they’re not a solution to tree root problems and won’t fix existing exposed roots. And excavating soil to bury a root barrier can make roots want to grow there because the soil is loose and there’s lots of water and oxygen.
However, there are some things you can do to limit the likelihood of roots growing upwards.
- Plant the right tree in the right place. Trying to fit a big tree in a small planting area ensures future root problems. Choose the right tree species for your soil and the size of your garden. Need help choosing the right tree? We’re here to help.
- Water your tree properly. Roots grow in search of water, so make sure to irrigate your trees “low and slow” so water soaks down into the soil. Roots will follow the water.
Exposed Tree Roots? Give Us a Call!
Contact the arborists at Rayzor’s Edge Tree Service for a tree consultation if your tree’s roots are growing in the lawn, cracking the walkway, or tripping passersby. We can determine what’s causing your tree’s exposed roots and recommend the best way to remedy the problem.
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