Using Treated Grass Clippings in the Garden
How long do you need to wait after you have a lawn sprayed with a weed killer before you can use the clippings as mulch in the garden?
There is some disagreement among the experts. I have seen anywhere from a two to six week waiting period recommended. I tend to go with the conservative recommendation. Leave grass clippings on the lawn after each cutting for at least 4 preferably 6 weeks after applying weed killer (herbicide) to your lawn. These clippings break down quickly adding moisture, nitrogen and organic matter to the soil. Long clippings can be cut down to size by making a second pass over the lawn with your mower. You can safely collect clippings six weeks after treating the lawn. A thin layer of herbicide-free grass clippings works well as mulch in the garden. Add a thin layer of fresh clippings each week.