Step 1
Position the blade over the area where you want to start your trench.
Step 2
Turn on the machine. Many trenchers are equipped with an electric starter, but smaller units may have a pull starter such as those on a lawnmower.
Step 3
Tilt the blade into the ground and slowly start to walk forward until you feel a sudden resistance stopping the saw from moving forward. The resistance likely means that you have encountered a root. Make sure to maintain a tight grip on the trencher's handle at all times, because a root can jerk the saw away from you.
Step 4
Hold the trencher in place as the blade spins. Slowly inch the blade forward as you allow time for the blade to cut. Be cautious -- once the blade cuts through the root, the saw might lurch forward when it reaches softer soil. Continue inching forward until you feel the resistance end.