Pine trees are great options for a home landscape, but as is the case with any tree, you should consider the tree’s below-ground growth as well as its above-ground growth before you plant.
All tree roots have the potential to become invasive, and pine trees are no exception. The best way to prevent damage is to choose your species and planting sites carefully, but if your pine tree is already established, you may still be able to mitigate damage.
How Far Do Pine Tree Roots Spread?
Pine tree root systems can encompass an area four to seven times the mature diameter of the tree (source) This is a crucial factor to keep in mind if you already have a pine tree or are thinking of planting one.
Keep in mind that pine tree root systems vary by species and soil type. However, there are important generalities to understand before planting a pine tree in your yard.
Many species of pine have a central taproot. A taproot is the largest root in a tree’s root system, growing vertically straight down from the tree’s trunk. Just beneath the surface, its diameter is similar to the trunk’s, but the taproot narrows rapidly as it grows downward.
Taproots reach depths of three to six feet, depending on the oxygen levels in the soil. Roots can’t grow where there is no oxygen, so once the taproot reaches a depth with little to no oxygen, it can’t go any deeper.
Extending outward from the taproot are several major lateral roots that can become quite woody and large. These grow parallel to the surface of the ground, often within the top 12 inches of soil where oxygen is most abundant.
Pine trees’ root systems vary in structure based on their species and soil type.
For example, while many species in the pine family have deep taproots, mugo pines don’t have taproots at all (source).
Furthermore, a 150-foot white pine will have a vastly more extensive root system than a four-foot dwarf cultivar.
The root systems also vary by soil type. For example, in sandy soils, many pine trees will develop two layers of roots. One layer grows near the surface of the soil and collects water and nutrients for immediate use, while a deeper layer of roots provides drought protection.
Often, this deeper layer of roots are offshoots of “striker” roots. Pine trees in dry soils and climates develop striker roots that act as secondary taproots.
Striker roots grow vertically from shallower lateral roots until they reach an obstruction or run out of oxygen. They anchor the tree more securely in the soil while also allowing a two-layer root structure to form.
If you aren’t sure what your soil type is, have your soil tested. A soil test can also tell you the nutrient content in your soil, its pH level, and whether there are any harmful fungi or bacteria living near your planting site.
Will Pine Tree Roots Damage a Foundation?
Tree roots of every kind–not just pine tree roots–need oxygen and water. They can’t grow in places where oxygen and moisture levels are low or nonexistent.
If the foundation of your home is solid and deep, a pine tree root might make contact with it but won’t be able to advance any farther to cause damage. In fact, it is more likely that your foundation will damage the tree. This is because the foundation won’t allow the root system to spread as much as it’s inclined to.
However, if your foundation is shallow, cracked, or if there is water collecting underneath it, tree roots may follow (source).
Furthermore, while your foundation may not be at immediate risk of damage from tree roots, your plumbing system could be. When pipes are shallow, old, or crumbling, tree roots can cause a good deal of damage. Consult a local plumber to determine if your pipes are at risk of damage.
What You Can Do
As much as possible, prevent water from collecting near the foundation of your home.
If you have flower beds or other landscaping near the base of your house, move them farther away or replant them in containers. This will prevent water collecting from potential over-irrigation.
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You can also examine your current gutters and make sure they drain well away from your foundation. You may need to consider adding extensions to your downspouts to direct rainwater farther away from your house.
If possible, avoid cutting the tree’s roots. While this may seem like the simplest or most obvious solution, it can lead to much bigger problems for you.
Any injury to the root system, intentional or otherwise, will injure the tree’s crown as well. Cutting off roots, particularly large ones, has the potential to weaken the tree to the point that branches, limbs, or the entire tree may collapse. This poses a danger to you, your home, and your vehicles.
Consult a local expert if you suspect that your pine tree may be damaging your house’s foundation. In some cases, the tree may need to be removed altogether.
Will Pine Tree Roots Damage Sidewalks?
Pine roots can damage sidewalks, driveways, and patios because many pine tree roots grow just below the surface of the soil. Sidewalks and driveways are usually shallow builds and don’t present a major obstruction to a tree’s root system. As a result, buckling, cracking, and crumbling occur where tree roots grow underneath the concrete.
What You Can Do
If you already have a pine tree, avoid constructing patios, driveways, or walkways within the area where your trees’ roots grow. Soil compaction, removal, and disturbance can all have an adverse effect on the tree itself. Trenching can kill the tree altogether or turn it into a major liability.
As much as possible, repair the damage in a way that allows for the continued growth of the roots. If that isn’t possible, and the damage creates a safety hazard, the tree may need to be removed.
Where sidewalk buckling is a concern, consider installing a concrete tunnel or a wooden bridge. These will allow the roots to grow normally while still providing a safe path for pedestrians.
There are two ways to prevent damage from invasive root systems before it happens:
- Choose the right pine tree cultivar.
- Choose the right planting location.
Some full-sized pine trees can be gigantic, but there are many dwarf varieties available that reach heights of 20 feet or less. Dwarf trees’ root systems aren’t nearly as extensive as standard-sized pine trees’ roots, which make them a good option for growers with small yards.
- Pinyon pines (Pinus edulis) are very slow-growing trees that reach a maximum height of approximately 20 feet (source).
- Mugo pines come in various dwarf cultivars, including “Green Candle,” which may only grow to 15 feet.
Furthermore, some pine cultivars are well-adapted to containers. If you want to avoid potential root problems altogether, consider planting a tree like “Paul’s Dwarf” Mugo Pine, Smidt Bosnian Pine, or another dwarf species available in your area.
Choose a planting site that receives full sun or partial shade for your pine tree. Pines can tolerate a variety of soils, but they do best when the soil drains well. For shady areas, read our guide on pine trees that grow in shade.
Keep the tree’s root system in mind as you choose your location. If your pine will be about eight feet in diameter at full maturity, its root system may extend at least 28 feet in diameter. You can avoid potential damage by keeping that area free of construction projects or planting your tree a safe distance from existing structures.
Once your pine tree is in the ground, you can also prevent root injuries by mulching around its base. Since pine tree roots often emerge from the soil as they grow, mowing and other mechanical injuries can be very problematic. A two to four-inch layer of bark mulch can protect your tree’s roots while still keeping your landscape attractive.
All tree roots have the potential to be invasive, which is why it’s important to do some research before you plant. Consider the tree’s mature size, the potential spread of its root system, your existing structures, and any planned construction projects. The right pine cultivar in the right location will be a great addition to your landscape or container garden.