An adapter for a landscape trimmer that includes a string head and an output shaft. The adapter includes an adapter body that has a first end and a second end, a string head portion, and a trimmer attachment portion. The string head portion is positioned proximate the second end and extends axially toward the first end. The string head portion is adapted to couple the string head to the adapter body. The trimmer attachment portion is positioned proximate the first end, and defines an unthreaded opening that extends axially toward the second end along the adapter body and that is adapted to receive the output shaft therethrough. The trimmer attachment portion further defines a slot that extends at least partially through the adapter body substantially transverse to and in communication with the unthreaded opening.