The best way to control weeds in the garden is to prevent them from getting started in the first place. Preen Extended Control garden weed preventer has a specialized formula to keep weed seeds from starting. 1-easy application of Preen Extended Control Garden Weed Preventer keeps over 200 broadleaf and grassy weeds from sprouting for up to 6-months. Your garden will stay weed-free all season long. Weeds rob desirable plants of water and other nutrients. Preen garden weed preventer stops weeds and eliminates time-consuming weed pulling chores. With Preen, you will be free to enjoy a beautiful, weed-free landscape.