Right Tree, Right Place: Tree Roots

It’s no surprise that what you see growing above ground on a tree will mirror that canopy in roots growing beneath the surface.

In fact, most tree roots spread two to three times the radius of a tree’s canopy or dripline.

But just like other plants, choosing the right tree with the right root structure can mean you get all the benefits of the trees you plant (abundant shade, vibrant fall color, wildlife habitats, and great landscape height and texture) without any of the negatives, such as invasive roots.

Some trees are best planted in particular locations that ensure their root systems can stretch out, and unfortunately, your yard is not always the best place for these trees.

Let’s look at some trees with invasive roots and what you can do to best manage them if you have them in your yard, as well as a list of trees with non-invasive roots so you can choose wisely next time you’re planting new trees in your home landscape.

Beware of Trees with Invasive Roots

Keep an eye out for these trees with more invasive below-ground structures that have the tendency to grow tree roots in areas you’d prefer to protect, such as your home foundation or nearby sewer lines.

• Willows – These trees, which grow to a height of 30 to 40 feet with a 35-foot spread, are notorious for their invasive root systems. The roots can invade water mains, wells, and home foundations to seek out water. Weeping willows are best planted by ponds where they can get all the water they need in USDA zones 6 to 8.
• Norway Maple – With a dense, round, symmetrical crown, Norway maples grow to 40 to 50 feet tall with a 30- to 50-foot spread in USDA zones 4 to 8. Its dark green leaves turn pale yellow in fall. But this tree is known for its potential to destroy foundations, sidewalks, and driveways with its roots. Plant this one at least 100 feet from your home to avoid these complications.
• River Birch – River birch is known for its peeling, two-toned bark and its love of growing near streams and river banks in USDA zones 4 to 9. While river birch roots aren’t a threat to nearby foundations, they do stay near the surface, making it tough to plant anything else near the tree. The roots also seek out water, taking advantage of cracks in water lines or sewer pipes. Plant them at least 20 feet from homes.
• American Elms – The stately elm has a vase-shaped, broad crown with green summer color and golden fall color. Growing in USDA zones 3 to 9, its numbers have been greatly reduced by Dutch elm disease over the years. The tree is also known for its invasive roots that often invade sewer lines and drain pipes.
  
  

Trees with Non-Invasive Roots

In your garden, you work within some limitations, which is a natural part of learning what plants will do best in your space. For instance, you might have a sunny yard or a lot of shade, and you want to choose plants that work best in those areas.

Following the same principle, you also have to work with trees that have non-aggressive roots near your home to avoid problems with roots impacting your foundation or sewer lines.

You might be wondering what trees have non-invasive roots. Here are some to try:

• Arborvitae – This hard-working, versatile tree has a narrow, pyramidal shape and offers privacy, as well as serving as a windbreak when planted in a row. As an evergreen, this tree keeps its green foliage year-round and grows best in USDA zones 3 to 7.
• American Holly – This evergreen tree’s leaves stay green year-round and have red, berry-like fruits that develop if you plant multiple trees that can cross-pollinate. The tree can reach 40 to 50 feet with an 18- to 40-foot spread in USDA zones 5 to 9.
• Stewartia – The stewartia is a popular ornamental tree that grows best in USDA zones 5 to 8. With a dense crown of oval leaves, this tree grows to 40 feet and exhibits summer blooms that look like camellias. In fall, the leaves turn to shades of reds, golds, and purples.
• Crabapples – Every year in May, the crabapple shows off its vivid magenta blooms. This compact, versatile flowering tree provides year-round interest, too, with handsome foliage and fruit that sticks around through winter to provide interest and feed the birds. This tree is great for the smaller spaces on your property since they come in a range of sizes – most not reaching more than 20 feet high – in USDA zones 3 to 8.
• Hornbeam – The American hornbeam is a relatively low-maintenance tree that grows to 30 feet tall with a 25-foot spread. This tree, found in USDA zones 3 to 9, enjoys full sun and adapts readily to dry conditions or poor soils, offering gray-brown bark and yellow to orange fall color. 
  
  

When is Tree Root Pruning Necessary?

Tree roots are meant to stretch out into the soil.

If they grow in a continuous circle around themselves, that’s called girdling, and usually, it means the roots are choking your tree, cutting off nutrients and water flow. This can happen below and above ground, and typically happens when a tree is planted in a hole that is too small or too deep.

Fixing girdling roots can be tricky since you want to relieve the tree but also not limit any supply of water or nutrients. Contact a certified arborist for help battling girdling roots.

Sometimes, you may want to do some tree root pruning if roots are growing in areas you don’t want them or where they are impacting other plants or your grass. This job should be carefully considered and is best done after consulting with a professional arborist.

Ideally, you want to avoid pruning roots more than 2 inches wide. This ensures you don’t negatively impact your tree’s stability. Also, never remove roots near to the trunk since those are critical to the tree’s structure. Winter and early spring are the best times for tree root pruning.

HERE ARE SOME ADDITIONAL RECOMMENDATIONS FOR SOME OF THE BEST AND WORST TREES TO PLANT NEAR YOUR HOME.

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