Kikuyu grass (Pennisetum clandestinum) is a warm-season perennial turfgrass known for its aggressive growth. While valued for hardiness and erosion control, it is widely considered an invasive weed in landscapes. Elimination is difficult due to its extensive network of stout rhizomes (underground runners) and thick stolons (above-ground runners). These structures form a dense mat, allowing the grass to quickly outcompete other species. Complete removal requires persistent strategies, as even small fragments of rhizome or stolon can quickly regenerate an entire patch.
Non-Chemical Eradication Techniques
For smaller infestations or those preferring an environmentally mindful approach, physical and environmental manipulation methods offer effective control. Manual removal is viable for isolated patches, but it demands meticulous attention to detail to prevent regrowth. Every piece of rhizome and stolon must be dug out and removed, as leaving fragments allows the grass to quickly rebound.
A non-chemical method is solarization, which uses the sun’s heat to kill the plant material in place. The process begins by mowing the Kikuyu grass low and thoroughly watering the area. A sheet of clear plastic is then laid over the patch and secured tightly around the edges to trap the heat. This creates temperatures sufficient to kill the grass and its root system, typically requiring four to eight weeks during the hottest part of the year.
Smothering is another technique that relies on blocking sunlight, which is necessary for the grass to survive. This involves laying down a thick, light-blocking material, such as heavy cardboard or a dense layer of mulch at least 10–15 centimeters deep. This exclusion method is slower than solarization, but it starves the grass of light, causing it to die off over several months.
Effective Chemical Control Options
Chemical intervention is often necessary for large, established infestations where complete renovation is the goal. The most common approach involves using a non-selective herbicide, such as Glyphosate, which kills any plant it contacts. Due to the grass’s robust root system, a standard application rate is often insufficient, so a higher concentration is recommended.
Timing the application is a major factor in achieving success with chemical control. Herbicides are most readily absorbed when the Kikuyu grass is actively growing and healthy, typically during the warmer months. It is beneficial to stress the grass slightly by cutting it back and allowing a few days of regrowth before spraying, which maximizes the leaf surface area available to absorb the chemical.
For complete eradication, multiple applications of the non-selective herbicide are required. A second or third treatment, separated by two to four weeks, is necessary to target any grass that survived the initial application or newly emerged from deeper rhizomes. Selective control of Kikuyu grass within an existing lawn of a different variety is challenging, often resulting only in suppression rather than total elimination.
In lawns composed of species like Couch or Zoysia, specialized selective herbicides may be used to suppress the Kikuyu without killing the desired turf. However, for turf varieties like Buffalo or Fescue, there are no selective chemicals available, making spot treatment with a non-selective product the only option. When applying any chemical, wear appropriate personal protective equipment and ensure wind conditions prevent drift onto desirable plants.
Post-Eradication Management and Prevention
Once the Kikuyu grass has been killed, the area requires careful preparation before replanting to prevent potential re-emergence. All dead plant material, including thatch and remaining runners, should be thoroughly removed through raking or light tilling. Improving the soil health and structure through aeration and the addition of amendments creates a better environment for new planting and discourages weed re-establishment.
When selecting a replacement for the eradicated Kikuyu grass, choosing a species that is competitive or more manageable is advisable. Certain varieties of Zoysia or hybrid Bermuda (Couch) grass are recommended because they can better withstand selective suppression methods that may be needed later. In areas intended for garden beds, installing a solid root barrier along the edges can physically block re-invasion from adjacent infested areas.
Long-term success depends on consistent maintenance practices that keep the new landscape vigorous and dense. Implementing deep, infrequent watering encourages the new plants to develop deeper root systems, and maintaining the appropriate mowing height helps it out-compete any potential Kikuyu seedlings or stray runners. Regular monitoring of the area is necessary to catch and immediately remove any signs of Kikuyu regrowth, preventing it from re-establishing a strong foothold.