To dig a perfect circle around a trees planted in the lawn:
- Loop a rope around the tree trunk, and attach it to the shaft of a spade.
- Adjust the length so that the spade reaches the desired distance from the tree.
- Use the spade to mark the outline of a circle.
- Remove the rope and dig down at the mark around the tree.
- Remove the turf under the tree and cover the area with mulch.