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The Right Tree in the Right Place: Tree Roots
It’s no surprise that what grows above ground on a tree will be mirrored in roots developing under the surface.
Most tree roots, in fact, stretch two to three times the radius of a tree’s canopy or dripline.
However, as with other plants, selecting the right tree with the right root structure can mean that you get all of the benefits of the trees you plant (abundant shade, vibrant fall color, wildlife habitats, and great landscape height and texture) while avoiding any of the drawbacks, such as invasive roots.
Some trees are best planted in specific areas to allow their root systems to spread, and your yard is not necessarily the greatest spot for these trees.
Let’s take a look at some trees with invasive roots and how to best manage them if you have them in your yard, as well as a list of trees with non-invasive roots so you may pick carefully the next time you plant new trees in your home landscaping.
Be cautious of trees with invasive roots.
Keep an eye out for these trees, which have more invasive below-ground structures and a tendency to sprout tree roots in places you’d rather not have them, such as your house foundation or neighboring sewage lines.
- Willows – These trees, which may reach a height of 30 to 40 feet and a spread of 35 feet, are known for their invasive root systems. To find water, the roots may infiltrate water mains, wells, and housing foundations. In USDA zones 6 to 8, weeping willows are best planted near ponds where they can obtain all the water they require.
- Norway Maple – Norway maples grow to 40 to 50 feet tall with a 30- to 50-foot spread in USDA zones 4 to 8. They have a thick, spherical, symmetrical crown. In the autumn, its dark green leaves become light yellow. However, this tree is notorious for its ability to demolish foundations, sidewalks, and roadways with its roots. To prevent these issues, plant this one at least 100 feet away from your house.
- River Birch – River birch is well-known for its peeling, two-toned bark and preference for growing along streams and river banks in USDA zones 4 through 9. While river birch roots may not pose a hazard to neighboring foundations, they do remain near the surface, making it difficult to plant anything else close. Water is also sought after by the roots, which take advantage of fractures in water lines or sewage pipes. Plant them at least 20 feet away from buildings.
- American Elms – The majestic elm has a vase-shaped, wide crown that is green in the summer and golden in the autumn. Growing in USDA zones 3 to 9, Dutch elm disease has drastically decreased its population over the years. The tree is also notorious for its invasive roots, which often infiltrate sewage systems and drain pipes.
Non-Invasive Roots Trees
Working under constraints in your garden is a natural aspect of discovering what plants will thrive in your environment. For example, whether you have a sunny yard or a lot of shade, you should select plants that thrive in those conditions.
To prevent difficulties with roots touching your foundation or sewage lines, you must also deal with trees that have non-aggressive roots near your house.
You may be curious in which trees have non-invasive roots. Here are several examples:
- Arborvitae – This hardy, versatile tree has a narrow, pyramidal shape that provides privacy while also acting as a windbreak when planted in a row. As an evergreen, this tree retains its green leaves all year and thrives in USDA zones 3 to 7.
- American Holly – The leaves of this evergreen tree remain green all year and it produces red, berry-like fruits if you grow many trees that may cross-pollinate. In USDA zones 5 to 9, the tree may grow to be 40 to 50 feet tall with a spread of 18 to 40 feet.
- Stewartia – A popular ornamental tree that grows well in USDA zones 5 to 8. This 40-foot-tall tree has a thick canopy of oval leaves and June blossoms that resemble camellias. The leaves become crimson, gold, and purple throughout the autumn.
- Crabapples – Every May, the crabapple displays its vibrant magenta flowers. This small, multipurpose blooming tree gives year-round appeal as well, with attractive foliage and fruit that remains on the tree throughout the winter to provide interest and feed the birds. This tree is ideal for tiny locations on your property since it comes in a variety of sizes, with most not reaching more than 20 feet in USDA zones 3 to 8.
- Hornbeam – The American hornbeam is a low-maintenance tree that grows to 30 feet tall and 25 feet wide. This tree, which grows in USDA zones 3–9, prefers full sun and adapts well to dry circumstances or poor soils, with gray-brown bark and yellow to orange autumn color.
When Is Tree Root Pruning Required?
Tree roots are designed to extend into the earth.
Girdling occurs when roots develop in a continuous circle around themselves, and it typically indicates that the roots are suffocating your tree, cutting off nutrients and water movement. This may happen both below and above ground and is most common when a tree is planted in a hole that is either too small or too deep.
Fixing girdling roots may be difficult since you want to alleviate the tree while without limiting its intake of water or nutrients. For assistance with girdling roots, contact a certified arborist.
If roots are growing in places you don’t want them or are interfering with other plants or your lawn, you may need to prune them. This task should be done with caution and after consultation with a certified arborist.
Ideally, you should avoid trimming roots that are larger than 2 inches broad. This ensures that you do not jeopardize the stability of your tree. Also, never remove roots close to the trunk since they are essential to the tree’s structure. The optimal seasons for tree root trimming are winter and early spring.