Yes, there is a weed preventer that you can sprinkle on the ground and it prevents weeds and all other seeds from sprouting. Do not use it if you are growing flowers from seed, but you can use it around perennials and annuals already growing in the ground. It is called Preen and it comes in an organic form for vegetable gardens. I do not know of any weed killer that will knock out weeds but not flowers - many weeds are just wild flowers or some plants that others grow as flowers (violas, dandelions, foxgloves) other gardeners think of as weeds. Best to hand pull the weeds near your flowers and then use a mulch or a product like Preen to keep them from coming back. Keep growing, Marianne Binetti