Mint is a popular, aromatic herb, but planting it directly into the ground quickly reveals its aggressive nature. The plant’s rapid, unchecked growth transforms a small patch into an invasive problem that chokes out surrounding vegetation. Because mint is so tenacious, standard weeding is ineffective, requiring a strategic, multi-pronged approach for complete removal. This article details the specific methods necessary to fully eradicate a mint infestation.
Understanding the Enemy
Mint’s persistence stems from its unique underground anatomy, allowing it to regenerate even after the above-ground foliage is cut away. The plant spreads primarily through rhizomes, which are horizontal underground stems that function as a robust root system. These rhizomes creep just beneath the soil surface, sending up new shoots wherever conditions are favorable.
A single mint plant can use these rhizomes to colonize a wide area, sometimes spreading up to a meter per year. The rhizomes are the plant’s energy storage organs, packed with carbohydrates that fuel rapid regrowth. Simply cutting or pulling the visible stems is insufficient because the buried rhizomes remain alive, ready to send up new growth. Leaving even a tiny piece of rhizome in the soil can result in a new plant, which is why aggressive removal techniques are essential.
Manual and Physical Eradication
The most direct, non-chemical method for mint removal involves rigorous manual excavation. The primary objective is to remove every segment of the plant’s extensive rhizome system. Use a garden fork or shovel to loosen the soil and gently lift the entire root mass, avoiding the breakage of brittle rhizomes. Dig down to a depth of at least six to eight inches, as the rhizomes may extend that far below the surface.
After removing the bulk of the plant, carefully sift the excavated soil to find and remove any small, spaghetti-like rhizome fragments. All removed plant material must be disposed of in the trash, not a compost pile, to prevent the fragments from rooting elsewhere.
A less intensive but more patient method is the continuous cutting or “starvation” technique. This process involves repeatedly cutting the mint stems down to ground level as soon as new growth appears. Constantly removing the foliage prevents the plant from photosynthesizing, depleting the energy stored in the underground rhizomes. This method takes several months of diligent effort to fully starve the plant, but it is a viable option for organic gardeners.
Environmental Suppression Techniques
Environmental suppression methods alter the growing conditions to kill the plant over a longer period. Soil solarization is an effective technique that uses the sun’s energy to superheat the soil and destroy the rhizomes. Clear the area, then water the soil deeply to increase its heat absorption capacity. Cover the infested area with a sheet of clear, six-mil polyethylene plastic, which traps the heat like a greenhouse, and seal the edges by burying them in a trench to prevent heat escape. Maintain this process for at least four to six weeks during the hottest part of the summer to raise the soil temperature high enough to kill the rhizomes.
Smothering is another effective suppression technique that deprives the mint of the sunlight it needs to survive. Cut the mint down to the ground first, then cover the area with a thick, opaque material like black plastic sheeting or several layers of cardboard. A layer of mulch, such as wood chips, can be placed over the top to secure the material and block all light. For small, isolated patches, such as mint growing in sidewalk cracks, carefully pouring boiling water directly onto the plant can scald the foliage and roots, providing a quick, targeted kill.
Chemical Solutions for Persistent Growth
When manual and environmental methods fail, chemical control offers a final solution for persistent or widespread infestations. Systemic, non-selective herbicides, like those containing glyphosate, are the most effective because they are absorbed by the foliage and translocated down into the rhizomes.
The application requires a specific technique to ensure the herbicide reaches the root system effectively. Cut back the existing mint growth, leaving only a few inches of stem and healthy leaves. The remaining leaves should then be lightly bruised or scratched to improve chemical absorption. Apply the herbicide directly and sparingly to this remaining foliage, avoiding spray drift onto surrounding desirable plants. This targeted application allows the chemical to kill the energy-storing rhizomes. Multiple applications may be necessary as new shoots emerge, and it is imperative that you follow all label instructions regarding safety and environmental runoff.