How deep do we grind a stump and the roots?

About 12 inches.

We get asked this question often. Maybe you want to plant a new tree where the stump was removed, or you want to sow some grass seeds to keep your property maintenance easy. If your stump is very small, we may be able to remove most of the roots with our grinder, but if it's a large tree, we won't be able to grind all the roots. Many tree root systems go down 6 to 24 inches under the soil and spread 2 to 3 times the radius of the canopy and sometimes more.

The roots will eventually die off, but we don’t really recommend that you plant a new tree on the same spot after stump grinding. The leftover roots could be an obstacle for the growth of the roots of the new tree, and the new tree may not grow well. If you want to sow some grass seeds, we recommend that you mix the mulch and soil. And if possible, adding nitrogen would be ideal. Mulch will take nitrogen from the soil. So your new glass might not grow well.