Lily of the Valley (Convallaria majalis) is a perennial admired for its delicate, fragrant, bell-shaped flowers that appear in spring. Often used as a shade-tolerant ground cover, its aggressive, spreading nature quickly becomes a burden for many gardeners. Its dense colonies rapidly overtake garden beds, crowding out other plants and becoming difficult to manage due to its robust, underground growth system.
Essential Safety Measures Before Starting
Before attempting to remove any part of this plant, implement strict safety precautions. Lily of the Valley is highly poisonous, containing cardiac glycosides that can disrupt heart function if ingested. All parts of the plant, including the leaves, stems, flowers, roots, and red berries, are toxic to humans and pets.
Wear heavy-duty, impermeable gloves, long sleeves, and eye protection throughout the removal process to prevent skin contact and accidental exposure. The toxins can cause dermatitis upon contact. All removed plant material, including soil containing root fragments, must be disposed of properly in sealed bags. Never add this material to a home compost pile, as composting risks incomplete breakdown of the toxins and could allow small rhizome pieces to resprout.
The Manual Removal Strategy
The most direct and labor-intensive method for eradication is the physical removal of the plant’s underground network. Lily of the Valley spreads relentlessly through white, slender, creeping rhizomes, often called pips. A small segment of a rhizome left behind can quickly regenerate a new plant, which is why standard surface weeding is ineffective.
Begin the process after a recent rain or thorough watering, as moist soil makes digging and sifting easier. Using a sharp spade or trowel, excavate the infested area to a depth of at least 8 to 12 inches. The goal is to get beneath the deepest rhizome growth zone to ensure complete removal of the root mass.
Once the soil is loosened, it must be meticulously sifted by hand or with a screen to locate and remove every tiny fragment of the white rhizomes. Breaking the rhizomes during the digging process creates new, viable pieces, so working slowly to lift and separate the entire network is preferable. To prevent future spread, use a flat-bladed shovel to cut a clean, vertical boundary around the perimeter of the infestation before digging the main area.
Chemical and Non-Chemical Eradication Methods
For large, dense patches or areas where mechanical removal is impractical, systemic methods offer an alternative approach. These methods aim to kill the entire plant by exhausting its underground resources, rather than relying on physical extraction.
Chemical Control
A systemic herbicide, such as a product containing glyphosate, is the most common chemical option for controlling this tough perennial. Systemic herbicides are absorbed by the foliage and translocated down into the rhizomes, killing the entire plant structure. The most effective time for application is in the late fall, as the plant is actively drawing energy reserves down to its roots for winter storage. Alternatively, application can be done in early spring when the leaves are young, increasing the speed of absorption. To protect surrounding desirable plants, apply the herbicide precisely to the Lily of the Valley foliage, using a brush or a specialized sprayer. Multiple applications are usually necessary, as the dense rhizome network often requires repeated treatment to be fully eradicated.
Non-Chemical Smothering
A non-chemical method called solarization or occultation uses covering materials to kill the plants by heat or light deprivation. Solarization involves covering the area with clear plastic sheeting during the hottest summer months, which superheats the soil and kills the rhizomes. Occultation uses thick, opaque materials like black plastic, cardboard, or damp newspapers covered with mulch to completely block sunlight. This smothering technique must be maintained for an entire growing season—ideally a full year—to starve the extensive root system of light and energy.
Preventing Regrowth and Long-Term Site Management
Complete eradication is rarely a single-step process, and long-term site management is necessary to prevent recurrence. New shoots will almost certainly appear from small rhizome fragments that remained in the soil.
Consistent monitoring of the cleared area is necessary throughout the following growing seasons, particularly in the spring. Any new sprouts must be immediately removed by spot-digging or by applying a targeted spot treatment of systemic herbicide. Removing the new foliage prevents the plant from photosynthesizing and replenishing energy stores in the remaining rhizome fragments.
After the area appears clear, replanting with competitive groundcovers or installing physical barriers will help prevent re-establishment. Consider planting species with dense, aggressive root systems, such as certain grasses or creeping thyme, which can effectively compete for soil resources. For a permanent solution, install a deep barrier, such as plastic edging buried 12 to 16 inches deep, to contain any residual rhizomes and prevent future lateral spread from adjacent areas.