If a lawn is healthy and lush there is less chance weeds will take hold. The weeds in your lawn may not have blown over from your neighbor's yard, but rather grown from seeds that were already in place, dormant from last season. With a little sunshine and water, they are able to germinate. If you cut your grass too short, this can lead to crab grass, as it gives dormant seeds better access to the sunshine. Before choosing a chemical to treat weeds, consider the type of lawn and weeds, as not all chemicals are appropriate for all lawns.
Fill a wand with the appropriate weed killer solution as recommended by your gardening center for the weed and lawn type. A wand is a long tool that resembles a pipe and is filled with weed killer solution.
Press the tip of the wand directly on each weed to release the solution. Instead of a wand, you can use weed killer that is prepackaged in a foam aerosol applicator.
Mow the grass if you intend to kill weeds close to hedges or other plants.
Drag a roller that has been covered in weed killer over the area close to the hedge or other plants to apply the weed killer. Do not touch the hedges or plants.
Fill a tank sprayer with water and the appropriate weed killer to treat a large area of the lawn. Apply to the weedy areas by pressing the hand pump on the sprayer and aiming the nozzle at the weeds.