I'm just curious, should a lilac tree be planted a certain distance from a house to prevent the roots from disturbing a foundation like a maple tree? Or are the roots not that intrusive?
Certified GKH Gardening Expert
It is highly unlikely that the lilac will cause damage to a foundation. They have very non-aggressive roots systems and is why you often see them used as foundation plants. They only way that it could be even a threat (and even then, the plant would probably die before it did damage) would be if the roots were restricted tightly, as in there were only a few feet for the roots to grow in. Planting the lilacs 8 to10 feet away from the foundation should be more than enough distance. As a general rule, tree roots will extend up to 2.5 times the height of the tree, and some species of trees may have roots extending five to seven times the height of the tree.