The University of California classifies Kikuyu grass (Pennisetum clandestinum) as an extremely aggressive weed. This native African grass was imported to the United States in the early 20th century to help reduce erosion. Once established in the United States, it spread quickly. Today, this invasive weed can be found growing in thick mats in lawns and gardens throughout most of the United States. To get rid of Kikuyu grass, you must kill its roots and prevent it from setting and germinating seed.
Remove patches of Kikuyu grass by hand. Use a trowel or shovel to dig up large patches. When you think you have removed and bagged all the roots and blades, dig through the remaining soil to make sure that all the root pieces are gone. Even small root sections can regenerate and grow new plants.
Spray patches of Kikuyu grass with herbicide if they cannot be dug up. Use a broad-spectrum herbicide and spray the patches of Kikuyu grass following the manufacturer's instructions. Broad spectrum herbicides that kill Kikuyu grass will also kill any other plants that they come into contact with. Spray close to the patches to minimize the amount of herbicide that comes into contact with any neighboring desirable grass. Cover any nearby desirable broadleaf plants with plastic before using broad spectrum herbicides near them. Respray kikuyugrass as needed following the manufacturer's instructions for frequency rates.
Apply a pre-emergent herbicide to your lawn in March to prevent the next generation of Kikuyu grass seeds from germinating. Reapply the pre-emergent herbicide at the rate recommended by the manufacturer until late summer. Re-apply the pre-emergent herbicide the next season to be sure all the Kikuyu grass seed has been killed.
Reseed any bare sections of your lawn left behind by dead or removed Kikuyu grass patches. First remove any dead grass blades. Then sprinkle the grass seed over the spot at the rate recommended for your particular species of grass (a centimeter or so's space between each grass seed is often sufficient). Press the seed into the soil by walking over it. Water it with 2 inches of water and keep the ground beneath the seed consistently moist until 2 weeks after the grass seed germinates.