How to Weed Grass


Weeds in the grass are a common problem that is difficult to control. Fortunately, with the use of an herbicide, rather than physical removal, you can kill the bothersome weeds, plant new grass and begin to grow a green, lush lawn. Then, with some cultural practices, such as mowing your grass at a higher height, you can keep your grass weed-free.

Step 1

Determine which kind of weeds you have growing in your grass. They typically fall under two categories--grassy or broadleaf. Grassy weeds have hollow stems, the leaf blades have veins growing parallel to the leaf margins and the leaves are typically two to three times as long as they are wide. Broadleaf weeds have showy flowers and the leaf veins run in different directions. If necessary, take a sample to a nursery or county Extension office for proper diagnosis.

Step 2

Purchase the appropriate herbicide spray, such as one that contains the active ingredient 2, 4-D or glyphosate, for the type of weeds you have. Ready-to-use bottles do not require any dilution and are easiest to use. Some herbicides are hooked to the hose and are diluted with the water in the hose as it is sprayed. Other herbicide can be poured into a herbicide sprayer (such as a backpack sprayer) and are then diluted with water. All sprayers have a lever in which you push in order to dispense the herbicide.

Step 3

Wear protective clothing and goggles and spray the herbicide when the air is calm and rain is not in the day's forecast. Keep animals and children indoors.

Step 4

Spray the herbicide according to the manufacturer's directions, usually in sweeping motions with your hands to evenly get the grass and weeds wet. Typically, herbicides kill the weeds within two weeks. However, spot treatment may be applied if some weeds survive. Reapply as often as the label states, sometimes just once in the spring and once in the fall when the weeds actively grow.

Step 5

Care for your lawn in a way that will inhibit weed growth. For example, most grasses should be mowed to a height of 2-1/2 to 3 inches. Also, cut no more than one-third of its height at any one time. Fertilize your lawn with a lawn fertilizer labeled for your type of grass, which is usually applied once every four to six weeks from spring until early fall. Irrigate your grass less often, but more deeply. Weeds have shallow roots and will be watered more if if you water just the surface on a regular basis. Most lawns need about 1 to 2 inches of water a week, especially during the summer.

Things You'll Need

  • Herbicide
  • Protective clothing


  • Texas A&M University: Weed Control in Turf
  • Colorado State University Extension: Control of Annual Grassy Weeds in Lawns

Who Can Help

  • University of Minnesota: Annual Grasses Perennial Weeds Index
Keywords: weed grass, control lawn weeds, kill grass weeds

About this Author

Melissa Lewis has been a professional writer since 2005. Her work has appeared in various online publications. A former elementary classroom teacher and media specialist, Lewis is also a script writer, with a movie script, "Homecoming," she co-wrote currently in production. She holds a Bachelor of Arts in psychology.