How to Kill Multiple Grasses in My Yard

Spray pre-emergent herbicide when ground temperatures reach 60 degrees Fahrenheit in the early fall. Pre-emergent herbicide is used to prevent grassy weed seeds from germinating. Weed seeds typically germinate when temperatures reach 60 degrees. Cover your entire lawn area with pre-emergent herbicide.

Water your pre-emergent herbicide into the soil. Pre-emergent herbicide must be watered into the soil to act as a barrier to prevent weed seeds from germinating.

Spray your lawn with a post-emergent herbicide to kill vigorously growing weeds. Post-emergent herbicide should be used when weeds are growing any time of the year. Use a selective post-emergent herbicide that targets unwanted weeds without killing your desired grass. Pick a dry day to apply the herbicide, so that it can become absorbed into the grass blades. Moreover, avoid mowing your lawn for two days before and after using the post-emergent herbicide.

Dip a paintbrush into a broad spectrum herbicide. Paint the broad spectrum herbicide onto blades of unwanted grass growing near ornamental plants and seedlings. Because ornamental plants and seedlings are sensitive to herbicides, it is best to avoid spraying herbicide right near the plant. Broad spectrum herbicide will kill grassy weeds without leaving behind a toxic residue.

Reapply pre-emergent herbicide in the fall to target cool season grass types such as bluegrasses.