With a height of up to 10 feet, a clump of pampas grass can make an impressive addition to your backyard. Due to its size, this ornamental grass can also overwhelm your landscape. If you change your mind about growing pampas grass, or if you acquire a backyard with pampas grass, you may be tempted to dig it out. This takes a long time, especially for mature clumps. Instead, go the faster route and chop it down before treating it with an herbicide.
Cut the pampas grass down to a height of 3 feet, or less, with pruning shears. Grasp a handful of pampas grass leaves together in a bundle and chop them away with the pruning equipment. Repeat until the entire pampas grass clump has been reduced to a more manageable size.
Spray what remains of the pampas grass clump with a standard glyphosate-based herbicide. Mist onto all exposed surfaces of the pampas grass, applying according to the guidelines on the herbicide's label as toxicity varies widely by product. The grass will die within two weeks.
Dig out the dead pampas grass, or leave it in the ground to decompose.