Answer: Japanese maples are shallow rooted trees, but the roots are not as troublesome as some of the larger and more notoriously surface rooted maples. These trees need a soil that is humusy and cool as well as evenly moist, yet well drained. They benefit from a layer of several inches of organic mulch year round, spread out to cover the entire root zone. This makes growing lawn beneath it unnecessary, but if you do grow lawn there, I would not expect to see roots at the surface. Finally, it is never a good idea to add soil over top of tree roots; the surface rooted trees such as maples will grow their roots right back again and there are other types of trees that are so sensitive to such a change that it can kill them.
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