My rotary spreader sometimes throws weed controls onto the flowers in the many flower beds in our back lawn. Any suggestions?

The Scotts  spreader would probably be best for you. It provides the speed of a rotary spreader, with the control of a drop spreader. The landscape protection can be activated to protect neighboring plants and shrubs. Where activated, the flow rate adjusts automatically to ensure even application. You can also use a drop spreader to applys material right up to your beds without worry of disturbing the flowers.