If you must cut through the roots of a live oak that you intend.

Mar 03, You can remove one or two surface roots a year, but consult an arborist first; and remove roots in the fall so the tree can recover before summer heat sets in. Consider groundcovers as a Estimated Reading Time: 50 secs. Of course cutting all the tree roots will in fact kill the tree. A general rule for cutting tree roots is don’t cut more than 25% of the root system. Measure the trunk diameter at about 4 feet from the ground. Take that measurement and multiply it by 6.

Mark off that distance from the trunk and that is about where 25% of the roots can be cut. See image below. For example if you have a 12″ diameter trunk 4 feet Estimated Reading Time: 2 mins.