24-63796/794 PREEN WEED PREV | Preen weed preventer stops weeds from germinating in flower and vegetable gardens, in ground covers and around trees and shrubs. Preen will not kill existing weeds. It will prevent new weeds from sprouting eliminates the need for difficult and time-consuming hand-weeding. Without weeds, your valuable plants can grow larger and stronger. Your beds will stay neat and weed-free all season long.