How to Kill Japanese Grass

August 30, 2018

Japanese grass, also known as stilt grass, is a prolific, invasive species that arrived in the United States from Japan, perhaps in packing materials, about 1900. It has a wiry stem from which sprout thin, pointed, lime green leaves that grow about 4 inches long. Japanese grass is unsightly in a lawn or garden, and troublesome in the wild where it breaks down the local habitat and drives out native species of plants. Since no American wildlife, including such near-omnivores as white-tailed deer, will eat Japanese grass, herbicides are the only effective method of eradicating it.

Things You’ll Need

  • 5-gallon sprayer garden hose attachment
  • glyphosate
  • agri-dex spray adjuvant
  • sethoxydim


Eradicate a small infestation of Japanese grass by pulling it out by hand, like any other weed. Japanese grass has a shallow root system which makes it relatively easy to uproot.

Spray a herbicide to eliminate an extensive infestation of Japanese grass. Look for a herbicide with glyphosate as its active ingredient and apply it undiluted over the affected area.

Mix 1/2 oz. of glyphosate with 1/4 oz. agri-dex spray adjuvant in a 2.5-gallon sprayer attached to your garden hose. Douse the affected area until all the herbicide solution in the sprayer is used up. The mixture will kill the Japanese grass without harming your garden plants. If you prefer not to mix your own herbicide solution, apply sethoxydim with a sprayer attachment. Sethoxydim, like the glyphosate and agri-dex spray adjuvant mixture, will eliminate Japanese grass without damaging other plants.

 Tips & Warnings

  • A single Japanese grass plant may release up to 1,000 seeds, which can remain vital for up to five years. The grass releases its seeds in September, so it is important that you eradicate Japanese grass no later than August.
  • It is likely that the seeds of Japanese grass will survive the first application of herbicide. Consequently it will probably take several years of spraying the affected area before the grass is eliminated completely.
  • Before using glyphosate, read the instructions on the container and follow them closely. Used improperly, glyphosate can cause short-term congestion of the lungs.


By Thomas Craughwell, eHow

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