Magnolias have a reputation for having invasive roots, but the challenge is more pronounced with the larger cousins of the Jane magnolia. Some magnolias can reach as high as 80 feet, and for a tree of that size, the roots need to be quite extensive to anchor it properly in the soil. The Jane magnolia, on the other hand, reaches a maximum of 15 feet, and thus has a correspondingly smaller footprint for its roots. However, magnolia roots in general spread wide rather than deep, so it's best not to plant your Jane magnolia too near your house or any other structure.