Gardeners with flourishing clumps of pampas grass often decide to eradicate it from their landscapes. Because of the unrestrained growth of pampas grass, it can quickly spread through planting areas and take over. When you decide it is time to kill pampas grass, use a combination of Roundup (glyphosate) and plastic sheeting while the grass is actively growing. With tenacious effort and attention to detail, you can remove this invasive ornamental grass.
Cut back the fronds of the pampas grass before applying Roundup. Use the hedge trimmers to cut the foliage back to approximately 8 to 12 inches above the soil level. Dispose of the fronds in a large garbage bag.
Apply the Roundup to the remaining pampas grass growth. Saturate the fronds completely and generously as well and the crown area at the base of the plant.
Cover the sprayed pampas grass with the plastic tarp. Spread the plastic over the entire clump of pampas grass and secure the tarp with rocks or bricks to keep it from moving.
Leave the plastic in place for at least a month (longer if desired). Remove the plastic when the pampas grass is visibly dead.
Dig out the pampas grass remains and dispose of them in a garbage bag (do not compost).