My landscaper planted a coral bark Japanese maple (Sango Kaku) and an Euonymus standard in my front lawn, about 1~2 feet away from the house foundation. I am wondering whether this could pose a threat to the house as the trees mature?
Thank you for contacting Toronto Master Gardeners about your new trees. When planting trees, it’s important to consider the mature size of the tree, as well as ensure you are planting the tree far enough away from your home. Tree roots can damage pipes, lift pavement, and be destructive to foundations. Most home foundations won’t be damaged directly by encroaching roots. However, moisture removed from the soil by trees and shrubs can cause subsidence (movement of the ground) that can damage the foundation. As well, too much water around the foundation (from watering the trees), could cause damage. A landscaping guideline for trees with mature height of 0-25 feet recommends planting trees a minimum of 8- 10 feet from a building or structure.
Let’s look at the mature sizes of the two trees you’ve planted. Coral Bark Japanese Maples (Acer palmatum ‘Sango Kaku’) are very popular trees with a lovely vase shape. I love the lime green leaves that turn beautiful shades of red, orange and gold in the fall. The mature size for these trees is 20 feet tall with a spread (width at the crown) of 15 feet A rule of thumb is that a tree should be planted at least a distance of ½ of their mature canopy width (spread) from a home. As a minimum, your Japanese Maple requires 7.5 feet (1/2 of the 15 feet spread) of space on all sides for adequate room to grow. Your tree, if planted 2 feet from your home, will quickly outgrow its current location. I recommend moving it out to at least 8 feet from your home.
I believe your other tree is a cultivar of Euonymus fortunei (tree form). These dwarf standard trees are popular because they are evergreen, very hardy, fast-growing , and easy to prune. This tree will be much smaller than your Japanese Maple. Mature tree size is height of 5 feet and spread of 2 feet. Due to their size and their dense, not deep roots, this tree could be classified as a medium to tall shrub. General guidance for a shrub this size is to plant it 4-5 feet away from the foundation.
If you decide to relocate your two trees, I recommend you transplant them before the roots become established in their current location. Good luck and enjoy your new trees!
Additional resource: The Morton Arboretum: Tree root problems
July 2, 2021