Mondo grass (Ophiopogon japonicus) is a popular perennial groundcover known for its dark green, grass-like foliage and adaptability to shaded environments. Although not a true grass, this member of the lily family forms dense, arching tufts. Its creeping nature, driven by underground runners or short rhizomes, makes it an attractive choice for filling garden spaces or acting as a border plant.
The vigorous growth that makes it desirable can also become a problem when the plant spreads aggressively into unwanted areas like lawns or pathways. The dense growth habit and tenacious root system make casual removal ineffective, often leading to persistent regrowth. Complete removal requires a deliberate, multi-pronged strategy addressing both the above-ground foliage and the extensive underground network.
Physical Removal Techniques
Manual removal is the most direct non-chemical method, suitable for smaller, isolated patches. This technique requires meticulous effort because the plant regenerates easily from small, remaining pieces of its underground structure. The focus must be on extracting the entire, often tuberous-rooted, rhizome system from the soil.
Using a sharp spade or trowel, dig around the perimeter of the patch, lifting the entire clump of soil and roots. Carefully sift through the displaced soil, searching for all the white, fleshy rhizomes and any attached tubers. Any fragment left behind has the potential to sprout a new plant, demanding thorough inspection of the excavated area.
For larger areas, less labor-intensive smothering techniques can be employed, though they require more time. Applying a thick layer of organic material, such as heavy cardboard or wood chips, blocks the sunlight necessary for photosynthesis. This process starves the plant of energy, causing it to die back over several weeks or months.
Solarization
Solarization offers another effective physical method by harnessing the sun’s energy to destroy the plant. This involves covering the mondo grass patch with clear or black plastic sheeting, which traps heat and raises the soil temperature. Clear plastic creates a greenhouse effect, while black plastic absorbs heat and simultaneously blocks light. This technique is most effective during the hottest months of the year and typically requires the area to remain covered for at least six to eight weeks for complete eradication.
Applying Herbicides Effectively
Chemical control provides an efficient solution for widespread infestations or areas where manual digging is impractical. Systemic, non-selective herbicides are recommended because they travel throughout the plant’s vascular system, ensuring the destruction of deep-seated rhizomes. Products containing glyphosate are preferred for penetrating the tough, waxy foliage and translocating to the root system.
To maximize absorption, first cut the foliage back to a few inches above the soil line. This exposes fresh cuts that serve as direct entry points for the herbicide, allowing for rapid movement to the roots.
The ideal time for application is during the plant’s active growth period, typically spring or early fall. Applying the herbicide during these periods ensures the chemical is transported to the rhizomes where it can cause the most damage. Application should be highly targeted, using spot-treating methods to avoid harming surrounding desirable vegetation.
A foam brush, wick applicator, or small sprayer can be used to paint the herbicide solution directly onto the freshly cut leaf stubs. This localized application technique minimizes the risk of spray drift. For best results, use a concentrated formulation, often mixed with a non-ionic surfactant. The surfactant helps the herbicide adhere to and penetrate the remaining leaf surfaces more effectively.
Safety Precautions
Safety is paramount during chemical application, requiring the use of personal protective equipment (PPE) such as chemical-resistant gloves, eye protection, and long-sleeved clothing.
Avoid application during windy conditions to prevent the herbicide from drifting onto other plants or into water sources. Additionally, checking the product label for a rain-free period, typically 24 hours, ensures the herbicide has enough time to be absorbed before being washed away.
The dense and resilient nature of the mondo grass rhizome network means that a single application is rarely sufficient for a permanent kill. It is necessary to conduct follow-up treatments, often spaced two to three weeks apart, targeting any new shoots that emerge after the initial application. These subsequent treatments eliminate any root fragments that survived the first round, ensuring a comprehensive, lasting result.
Ensuring Complete Eradication
After the foliage has withered and died, the post-treatment phase focuses on monitoring and prevention to ensure the plant does not return. Proper disposal of the dead material is important, as even roots that appear dead can sometimes harbor enough energy to sprout.
The removed dead plant material, including root balls and rhizomes, should not be placed into a home compost pile unless it reaches reliably high temperatures. Bagging the material for municipal waste disposal is the safest method to prevent accidental re-establishment of viable plant fragments.
Long-term prevention involves establishing physical boundaries, especially if new groundcover will be planted nearby. Installing a durable plastic or metal edging around the area, buried at least six inches deep, creates a barrier that blocks the lateral spread of any surviving rhizomes.
The cleared area requires continuous monitoring for at least one full growing season to catch any latent regrowth. Any small, new sprouts must be removed immediately, either by spot-treating with herbicide or by digging out the isolated root fragment. This vigilance is necessary to break the cycle of regrowth before the plant can re-establish a significant root network.