Kikuyu grass (Pennisetum clandestinum) is a popular, warm-season turf species native to East Africa. It is utilized in warmer climates for its aggressive growth habit, making it effective for erosion control, pasture forage, and durable sports fields. When used in residential settings, however, its vigorous nature often transforms it into a high-maintenance nuisance. Homeowners must understand the unique challenges this grass presents to effectively manage their turf.
Unruly and Invasive Growth Habits
Kikuyu grass’s reputation as a difficult species stems from its specialized biological structure, which combines both above-ground stolons and below-ground rhizomes. The plant produces thick stolons that creep rapidly across the soil surface, quickly colonizing adjacent flower beds and walkways. Simultaneously, robust rhizomes beneath the soil allow it to penetrate and emerge through mulch, paving cracks, and even shallow root barriers.
This dual-growth mechanism enables rapid lateral spread, quickly turning a small patch into an unmanageable lawn area. The high rate of vegetative reproduction translates into demanding maintenance schedules. During peak growing seasons, the turf often requires mowing twice weekly just to maintain an acceptable appearance and prevent lodging, which makes subsequent cuts difficult.
The thick, interwoven mat created by the runners contributes to a dense, tough texture that resists ordinary cutting implements. Homeowners often need heavier-duty mowers or specialized sharpening techniques to achieve a clean cut without tearing the leaf blades. This aggressive habit is the primary factor making the grass difficult to contain within defined boundaries.
Severe Thatch Accumulation
A consequence of Kikuyu grass’s vigorous growth is the rapid development of a dense organic layer known as thatch. This accumulation of living and dead stolons, rhizomes, and leaf matter builds up beneath the green leaf canopy. Kikuyu’s aggressive production of runners accelerates this accumulation, often creating a layer several inches thick within a single season.
This thick layer acts as a physical barrier, impeding the movement of water and dissolved nutrients down to the root zone. It also creates a spongy surface texture that makes walking difficult and interferes with sporting activities. The constant moisture and insulation provided by the thatch create an ideal microclimate for fungal pathogens and insect pests to thrive.
Managing this issue requires periodic intervention, typically through mechanical dethatching or verticutting once or twice a year. These processes use specialized equipment to slice through and remove the built-up organic matter, restoring gas and moisture exchange.
Susceptibility to Specific Diseases and Pests
The dense, matted structure of Kikuyu grass makes it susceptible to diseases that capitalize on low airflow and high moisture retention. One common issue is “Kikuyu Yellows,” often linked to a fungal pathogen or a nutrient deficiency, such as iron or nitrogen. This condition appears as a patchy yellowing or chlorosis that spreads rapidly across the turf.
Another prevalent fungal issue is Brown Patch, caused by the Rhizoctonia solani fungus, which thrives in the warm, humid conditions trapped within the thick thatch layer. The disease presents as circular patches of brown, dying grass, often with a smoky gray ring at the outer edges during active infection periods. Management requires improved drainage and targeted fungicide applications.
The thick turf also provides shelter for insect pests, such as mole crickets and armyworms. Mole crickets damage the grass by tunneling beneath the surface, disturbing and feeding on the roots and stolons. Armyworms consume the leaf tissue, often causing widespread defoliation.
Strategies for Containment and Removal
Due to the aggressive growth of rhizomes and stolons, containing Kikuyu grass requires intensive methods beyond standard lawn edging. To prevent lateral spread into garden beds, homeowners must install physical root barriers made of plastic or metal sheeting, buried 6 to 12 inches deep, to block the subterranean rhizomes. Regular, sharp edging is also necessary to sever surface stolons before they establish themselves in undesired areas.
When removal is the goal, complete eradication is difficult because any remaining rhizome fragment can regenerate a new plant. The common chemical strategy involves applying non-selective herbicides, such as glyphosate, which is absorbed through the leaves and translocated to the roots. Multiple applications, often spaced several weeks apart, are required to ensure the deep root system is fully killed.
A limitation with chemical removal is the thick thatch layer, which can block the herbicide from reaching the soil and lower parts of the plant. Physical removal is labor-intensive, requiring deep digging to ensure all rhizomes are extracted, often down to a depth of 12 inches or more.
A thorough, non-chemical approach involves solarization, which entails covering the area with clear plastic sheeting for six to eight weeks during the hottest part of the year. This process uses solar heat to raise the soil temperature high enough to kill the grass, seeds, and any remaining rhizome fragments, offering a complete method of suppression.