Tall deep and spongy grass needs to be pre-mowed to around 75mm (3 inches)* in order to allow decent wire installation and initial mowing session by the RK. It is recommended to use another mower or a lawn service to cut your grass to this level. Set the RK 75mm (3 inches)* height of cut and gradually, over weeks, lower it to the height you want.
*St. Augustine grass can be set between 3.5 inch and 4 inch (88mm to 100mm) if needed. Since it is typically
recommended to cut it higher