The ornamental design for a gardentoolgrip, as shown and described.
FIG. 1 is a top right perspective view of a garden tool grip showing our new design;
FIG. 2 is a right side view thereof;
FIG. 3 is a left side view thereof;
FIG. 4 is a top view thereof;
FIG. 5 is a bottom view thereof;
FIG. 6 is a rear view thereof; and,
FIG. 7 is a front view thereof.
The broken lines in the drawings are included for the purpose of illustrating portions of the garden tool grip that form no part of the claimed design.