Nut grass, also called nutsedge, is a difficult weed to control because it gets most of its energy from small legumes underground. As a result, it can withstand above-ground assaults effectively and continue to spring back long after other weeds would have given up the ghost. However, by understanding how to attack nut grass from several angles--and what time of year it is most vulnerable--you can get rid of nut grass.
Weed the yard by hand. Nut grass must be removed carefully to ensure that all of the small legumes, which look like nuts, are removed from the soil along with the leafy part of the weed. Weed when the soil is damp to lessen the likelihood of the root system breaking off, and use a spade to help dig out problematic plants that refuse to let go.
Let your grass grow. Adjust your mowing height to 2 1/2 to 3 inches. This will help your lawn keep the nut grass out on its own by simply overwhelming it.
Water deeply and seldom. This type of watering will help your grass develop deep root systems and will parch nut grass, which cannot establish deep roots.
Mix up a nut grass-killing herbicide. In the sprayer, combine a nut grass-specific herbicide and the non-ionic surfactant at a ratio of 1/3 fluid oz. per gallon.
Treat nut grass starting in late spring and early summer. This is the time of year when nut grass is most susceptible to effective removal. Treating the lawn with a nut grass-specific herbicide before the nut grass appears in late spring can help keep your lawn clear.