Zoysia grass is a warm-season turf often planted for its dense, drought-tolerant qualities, but its aggressive growth habit can quickly turn it into an invasive weed. The difficulty in eradication stems from its extensive network of above-ground stems (stolons) and deep, underground stems (rhizomes). These spreading structures allow the grass to choke out other plants. Since Zoysia can regrow from even small, remaining rhizome fragments, removal requires a comprehensive and persistent strategy.
Physical and Mechanical Extraction
Removing Zoysia grass without chemicals relies heavily on physically extracting the entire root and stem structure from the soil. For small, isolated patches, manual digging is effective, but you must be meticulous about removing every piece of the dense, wiry rhizomes. These underground stems often run 8 to 12 inches deep, necessitating careful excavation.
For larger areas, renting a sod cutter can slice the turf layer horizontally, making it easier to roll up and remove. After the sod is lifted, the soil must be thoroughly sifted to locate and remove any broken rhizome fragments, which will quickly re-sprout. All removed material should be bagged and disposed of, as composting is not recommended due to the high likelihood of rhizomes surviving.
Chemical Eradication Strategies
Chemical removal is often the most reliable method for eliminating established Zoysia grass, particularly for large infestations. The most effective option is a non-selective herbicide, such as those containing glyphosate, which kills any plant it contacts by systemic action. This herbicide is absorbed through the leaves and travels down to kill the extensive rhizome system. Best results occur when the grass is actively growing, typically in late summer when temperatures are above 60 degrees Fahrenheit.
Effective eradication usually requires a “spray-wait-spray” approach, as a single application is rarely enough. After the initial application, which should fully coat the leaves without runoff, wait two to four weeks for the grass to die back. Then, reapply the herbicide to any persistent green shoots. When using a non-selective product, shield desirable plants (e.g., with cardboard) to prevent accidental contact. Mixing a blue marking dye into the solution is helpful to track treated areas and ensure complete coverage.
Organic Suppression Techniques
For those preferring non-chemical options, passive methods that manipulate the environment can effectively suppress Zoysia growth. Solarization uses clear plastic sheeting, typically 2 to 6 mil thick, spread tightly over the area to trap solar heat. This process raises the soil temperature to levels lethal to the grass and its seeds. The soil must be saturated with water before covering, and the edges of the plastic must be sealed to maximize heat retention. This method works best during the hottest months of summer, usually requiring four to six weeks.
Alternatively, sheet mulching, or smothering, involves covering the grass with opaque materials like cardboard or black plastic to block all sunlight. This technique is slower, starving the grass of light over six to ten months, but it is effective in areas that do not receive full sun.
Post-Removal Management and Prevention
Once the Zoysia grass has been successfully removed or killed, attention must turn to managing the soil and preventing re-emergence. The area should be monitored vigilantly for at least the first year, as small, missed rhizome fragments can easily sprout new growth. Any new Zoysia shoots that appear should be immediately spot-treated or manually dug out to prevent a new infestation.
Before re-establishing a desired lawn or garden, it is beneficial to amend the soil, as the removal process can disrupt the soil structure. Incorporating compost helps restore soil health and provides an optimal base for new growth. Re-establishment can be done by planting quick-growing cover crops or installing sod, creating a dense, competitive canopy that helps suppress future weed growth.