Skunk cabbage (Symplocarpus foetidus and Lysichiton americanus) is often considered a nuisance. These large, fast-growing plants form dense colonies in wet, boggy, and shaded areas, such as swamps and stream banks, where few other plants can thrive. The common name comes from the foul odor released when the leaves are bruised or the plant is in flower, which attracts insect pollinators.
The main challenge in eradication is the plant’s robust, deep-reaching root system (rhizomes), which allows it to regenerate easily. Full removal is a long-term commitment, often requiring multiple seasons of persistent effort to deplete the plant’s energy reserves and the seeds stored in the soil.
Manual and Physical Removal Strategies
The most environmentally conscious approach involves physically removing the plant, ideally in late spring or early summer when the plant is actively growing but before it has set seed. Manual removal requires digging out the entire root structure, or taproot, which can be massive and difficult to extract from saturated soil. Since small root fragments can regenerate, excavation must be thorough and deep, often 6 to 12 inches.
Repeated cutting of the large leaves is a non-chemical strategy that depletes the energy stored in the roots over time. Consistently cutting back the foliage prevents the plant from photosynthesizing and replenishing its reserves, leading to eventual death, though this requires consistent monitoring and a significant time investment. Flower heads should also be removed in early spring before they set seed, as seeds can remain viable in the soil for up to eight years.
To smother smaller patches, thick layers of mulch or solarization sheeting can be applied for an entire growing season or longer. Always wear protective gloves and clothing during manual removal, as the sap can cause skin irritation. Proper disposal of removed plant material is necessary; it should be burned, securely composted, or dried out away from any water source to prevent the spread of viable seeds or root fragments.
Chemical Control and Application Timing
Chemical control is most effective using a systemic herbicide containing glyphosate, which is absorbed by the foliage and translocated down to the root system. Because skunk cabbage grows in or near aquatic environments, it is imperative to use only formulations of glyphosate specifically labeled and approved for use in or adjacent to water. These specialized aquatic herbicides are designed to break down without causing significant harm to the surrounding ecosystem.
The most precise and effective chemical method is the cut-stump application, which minimizes the risk of non-target contamination. The plant’s leaves should be cut off near the ground, and a concentrated, undiluted herbicide product should be painted immediately onto the fresh cut surface using a brush or sponge. This application must occur quickly, ideally within five minutes of cutting, before the plant can seal the wound and prevent absorption.
Application timing is crucial for maximizing the herbicide’s effect on the robust root system. The best time for systemic herbicide use is late summer or early fall when the plant is actively preparing for dormancy and drawing energy and nutrients from its leaves down into the roots. This downward flow carries the herbicide directly into the root crown, providing a more lethal dose. Due to the waxy nature of the large leaves, the cut-stump method is often preferred over foliar spray applications.
Long-Term Site Restoration and Prevention
Eradication requires a commitment to monitoring and site alteration to prevent re-establishment after initial removal. The area must be checked regularly for new seedlings or sprouts, which can emerge from the persistent seed bank for several years. Any new growth should be manually removed immediately to prevent re-colonization.
One of the most effective long-term strategies is to alter the site conditions, making the habitat less appealing to the plant. Improving drainage or changing the grade to prevent standing water makes the soil less saturated and less conducive to skunk cabbage growth. Removing the plant creates bare soil, which must be quickly filled with competitive, non-invasive groundcovers to prevent new seeds from germinating.
Selecting native plants that tolerate wet, shaded conditions is an effective way to outcompete any remaining skunk cabbage sprouts. Suitable options include:
- Golden Ragwort (Packera aurea)
- Sensitive Fern (Onoclea sensibilis)
- Marsh Marigold (Caltha palustris)
- Various native sedges (Carex species)
These competitive species utilize the same resources as the skunk cabbage, creating a dense canopy that limits light and makes the area inhospitable to the returning plant.