Mowing and walking over exposed tree roots are a nuisance, leading to falls and damaged lawn equipment. However, there are few ways to landscape around the roots to protect yourself, your mower, and your tree.
Use breathable materials such as mulch or small gravel to cover roots, yet allow them to continue to absorb water and nutrients. Small perennials and ground cover plants can also make the area look pleasing. Covering up tree roots with thick material or pruning them will damage the tree and affect its longevity.
Before we understand how to deal with exposed, or girdling, roots to improve your landscaped yard, it is important to know about the factors that cause them. These factors may determine if and how to landscape around the tree.
Why Are Tree Roots Exposed?
Exposed roots are the result of natural and human-made environmental conditions that erode or compact the ground’s surface. Trees’ roots are essential for survival, so they will grow where they can reach nutrients, water, and oxygen to do so.
Natural Environmental Conditions
Rain and other precipitation will compact bare soil. As a result, rain can runoff this hardened surface instead of soaking into the deeper layers where the tree roots are.
Roots will grow up to reach the water.
Rain and wind also can erode soil away, leaving the roots exposed.
Moist or wet growing conditions can force tree roots to move up towards the surface to avoid rotting.
Human-Made Environmental Conditions
Construction, landscaping efforts, water or gas pipe installation, driveways, and more can disrupt a tree’s root growth. Concrete and other hard materials compact the soil underneath, making water, oxygen, and nutrients hard to obtain.
If there is not enough space for the roots to grow and spread out to find nutrients and water, they can rise to the surface to seek them.
Additionally, if people or vehicles consistently move underneath a tree, the surface can become eroded or compacted by traffic, exposing the roots.
The nature of trees involves the establishment of a strong root system.
Trees grow lateral, or feeder, roots near the surface of the top soil and near the base of the tree. These roots anchor the tree and transport nutrients and are located 8 to 12 inches below the surface.
Lateral roots may have roots hairs to absorb more nutrients or sinker roots that extend off them that go deeper down, about 4-feet.
Lateral roots grow each year, which is why they eventually appear on the surface. If you were to cut one, you would see growth rings inside just like you would on the trunk of a tree.
Roots can also form as a result of ground obstacles or injury in an attempt to find nutrients and survive.
Roots will extend out to the dripline, or the outer circumference of the tree’s branches, and further.
Tree roots can become woody and tough as they grow in diameter to support a larger tree. The increased size of these roots can appear through the surface of the soil as the tree matures.
Certain types of trees develop shallow roots in their growing cycles. This is so they can grow in soil that is less than ideal due to sandy, rocky, or wet conditions.
Problems From Exposed Tree Roots
Tree roots that pop up out of the ground can cause several problems and nuisances.
These include the following:
- The lawnmower blade (or other landscaping equipment) may hit the roots becoming dull or damaged.
- Damaged roots invite disease, pests, and rot into the tree.
- Surface roots can crack sidewalks and other surfaces.
- The ground is uneven, posing a trip hazard.
- The roots are an eyesore.
4 Ways To Landscape Exposed Tree Roots
The following landscaping options will protect the roots of your tree and offer you ways to improve the overall look of your yard.
1. Cover Roots With Organic Mulch
Grass and other plants underneath a tree will compete for water and nutrients. This is often why many varieties of plants may struggle to grow where there are exposed or extensive roots.
You can cover exposed roots at the base of a tree with a thin layer of organic mulch, about 2 to 3 inches thick. Mulch will offer a porous surface and create a tidy appearance.
Do not use too much mulch or you will suffocate the roots. Keep the mulch a few inches away from the base of the trunk, so that rainwater can drip down the trunk to water the base as well.
Gravel mulch can be used as well, if you use a thin and loosely compacted layer of pea gravel or small stones so that water can still get in.
If you see yellowed or atypically small leaves during the growing season after mulching, the tree is struggling. Remove the mulch, make the layer thinner, or try a different strategy.
This video demonstrates how to properly mulch around a tree:
2. Sowing Plants
A landscaper can help you design the area or you can do it yourself.
Moss or ivy ground cover plants work well to cover an area underneath a tree.
You can create a larger circle of covered space and plant tree friendly plants underneath to make a landscaped area in conjunction with mulch.
Opt for perennial plants that grow well in shade and can tolerate drought-like conditions, since they will compete for nutrients and water with the tree.
A professional at the garden store can help you find plants that will thrive under a tree.
Take care to not damage the exposed roots with your shovel when planting. Consider edging this area with some pavers or large stones.
Alternatively, you can use a combination of mulch and plants to create a “well” around the tree. Do this with some mulch or gravel inside a barrier of pavers, stone, PVC edging, or roofing tin. Then, sow plants on the outside of the well to hide the barrier line.
3. Loosen Compacted Soil
Use a hand-held air spade. This is a device that utilizes compressed air to remove compacted soil.
An air spade is designed for use around a tree’s sensitive roots. Follow the instructional label for proper use.
You can then mix nutrient-rich, organic compost in with the loosened soil.
This may cover the roots temporarily, they will likely become exposed over time due to precipitation. However, by loosening up the compaction, the roots may slow down their exposure since they can find healthy nutrients down below.
You should not deeply bury the roots with more soil. The roots will likely push towards the surface again, or struggle to stay healthy resulting in illness to the tree.
4. Let The Grass Grow
For tree roots that are exposed further out from the base, you can allow the grass to grow taller. These roots can cause a trip hazard, so you will need to walk with caution.
However, by allowing the grass to grow up around the roots, you hide the unsightly appearance. Also, when you raise the blade cutting height on your lawnmower, you protect both the blades and the roots from damage.
Landscaping Practices That You Should NOT Do
The following practices will likely cause more damage to your tree.
If the roots look dead or are too bumpy, you should not cut or grind them down.
Woody roots in particular are still thriving and may have feeder roots that extend down from them. The tree needs these roots to stay alive.
If you weaken the tree by cutting or pruning it may be prone to disease or even a weak support system that can make it topple in extreme weather.
If roots are creating havoc for a foundation, walkway, or driveway consult with an arborist for the best course of action.
Paving Over Roots
Do not pave over existing roots, since they may die or grow bigger underneath it. Either way, the roots shift the ground, resulting in uneven surfaces and cracks in the paving.
Using Plastic Weed Barrier
If you mulch a thin layer underneath a tree, use a weed barrier that breathes. Generally these look like a mesh that allows air and water to enter. Refer to the packaging instructions.
Alternatively, a layer of newspaper is breathable underneath mulch.
Laying a new foundation or digging deeply near a tree can cause extensive damage to it. When making plans for new construction near a tree, consider if it will affect the health of it.
In many cases, a large tree with established roots will need to be removed for construction projects in the same vicinity.
Parking Underneath A Tree
You should not park your vehicle underneath a tree for shade directly on the roots or soil. The weight of your vehicle will compact the soil eventually causing damage to the roots.
Putting A Bench Under The Tree
Sitting in the shade on a bench underneath a tree seems delightful. However, if the roots are exposed, you are also exposing them to increased traffic and soil compaction.
Ideally, you should leave exposed tree roots alone. The tree needs them to survive.
To improve the area, you can use a light layer of mulch, ground cover and perennial shade plants, or an air spade to loosen compacted soil.
Contact a tree expert if you are unsure of what is best for your landscaping needs and health of your tree.