Glyphosate is a good weed killer that is commonly applied in the fall from Sept. 1 through Oct. 15. This herbicide is nonselective, meaning it kills most weeds including grasses and broadleaves. The disadvantage of using this weed killer is that it can harm other desired plants as well.
For proper weed control, identify the type of weeds before selecting one or a combination of herbicides. For example, 2,4-D and dicamba are good herbicides for controlling dandelion and broadleaf weeds in lawns. Then, check the herbicide label to see if it is safe to use with other plants in your garden. Follow all application instructions carefully to ensure success in controlling the weeds.
Some herbicides are preemergent, meaning that they are applied before the weeds appear. Other herbicides, called postemergent, are sprayed on young weeds.