Mondo Grass (Ophiopogon japonicus) is a popular perennial groundcover frequently used in landscaping due to its deep green, grass-like foliage and shade tolerance. Although commonly called a grass, it is actually a member of the Asparagaceae family, related to the lily. This plant spreads via underground runners (rhizomes), forming a dense mat, but also aggressively creeping into lawns, walkways, or adjacent planting beds. Complete removal requires a methodical approach that targets the entire root and runner system.
Confirming the Target and Site Preparation
Before beginning the removal process, it is important to confirm the target is truly Mondo Grass, as it is often confused with its close relative, Liriope (Lilyturf). Mondo Grass typically has narrower, darker green leaves and is shorter, usually growing between 6 and 12 inches tall. Its flowers and resulting small, blue berries are usually hidden beneath the foliage, unlike Liriope, which often has showy flower spikes that extend above the leaves.
Once the target is confirmed, preparing the site will significantly aid in the physical removal process. Start by clearing any loose debris, such as mulch or dead leaves, from the affected area to gain full visibility of the plant clusters. If manual digging is the chosen method, thoroughly soaking the area with water one day prior will help loosen the soil, making it easier to extract the root system and runners intact. If the Mondo Grass is growing intertwined with desirable plants, carefully mark the boundary to avoid damaging them during the process.
Manual and Mechanical Removal Strategies
Manual removal is often the most effective method for complete eradication because it ensures the physical extraction of the underground runners. Mondo Grass spreads through rhizomes and stolons, and missing even small fragments means the plant will likely return, sometimes within a single growing season.
The primary tool for this task is a sharp spade, a garden fork, or a trowel for smaller patches. Begin by digging around the perimeter of the patch, aiming to lift the entire mat of roots and soil in sections. Dig down at least 6 to 8 inches, or until the soil is clear of all white or tan root material, to ensure complete removal of the runners.
For very large, established areas, mechanical methods can save considerable time and effort. Renting a sod cutter can effectively slice and lift the dense, shallow root mat from the soil. After the sod cutter has passed, the loosened soil should still be sifted or carefully raked to find and remove any deeper, detached rhizomes that the machine may have missed.
Herbicide Application for Mondo Grass
When manual removal is impractical due to the size of the area or sensitive adjacent plants, a chemical approach may be necessary. Mondo Grass is resilient, requiring a non-selective, systemic herbicide, typically one containing glyphosate. This chemical is absorbed by the foliage and translocated down into the rhizomes, killing the entire plant structure.
Application should only be done when the Mondo Grass is actively growing, usually during the warmer months, to ensure maximum translocation of the herbicide to the roots. Because the plant is tough, it often requires multiple applications spaced several weeks apart. A non-ionic surfactant can be added to the spray mixture to help the herbicide penetrate the narrow, waxy leaves, improving effectiveness.
To protect surrounding turf or ornamental plants, use a targeted application method, such as a foam brush or a sponge, to wipe the herbicide directly onto the Mondo Grass leaves. This technique minimizes the risk of overspray or drift, which is especially important because glyphosate will kill nearly any plant it contacts. Dwarf Mondo Grass varieties are particularly sensitive to herbicides.
Preventing Regrowth and Disposal
Proper disposal of the removed plant material is necessary to ensure the Mondo Grass does not return. Since the rhizomes and stolons can sprout new plants even after being severed, clumps should not be placed in a compost pile or left on the ground. Instead, bag the debris and dispose of it with household waste or take it to a facility that handles aggressive plant debris.
After the initial removal, treat the soil to eliminate any remaining dormant root fragments. One effective method is soil solarization, where the cleared area is covered with clear or black plastic sheeting. Securing the edges of the plastic and leaving it in place for several weeks during the hottest part of the year will use solar heat to raise the soil temperature to a level lethal to any lingering rhizomes.
Alternatively, covering the area with a thick layer of cardboard followed by a heavy layer of mulch can smother any small sprouts that attempt to emerge. Once the soil has been treated and confirmed free of regrowth, the area is ready for replanting with desired groundcovers or turf. Planting new material helps utilize the cleared space and prevents new weed seeds from establishing themselves.