Creeping Charlie (Glechoma hederacea) is a persistent, low-growing perennial weed that often invades shaded lawns. This aggressive member of the mint family forms dense mats that choke out turfgrass. A popular do-it-yourself control method uses borax (sodium tetraborate) due to its specific chemical action against this weed.
Understanding Creeping Charlie and the Borax Mechanism
Creeping Charlie is identified by its square stems and small, kidney-shaped leaves with scalloped edges. In spring, it produces small, bluish-purple flowers, and the crushed foliage emits a distinct, mint-like odor. The plant spreads aggressively through creeping stems called stolons, which root at the nodes. This makes manual removal difficult, as small fragments left behind can regrow.
Borax application works because Creeping Charlie is unusually sensitive to the trace element boron, which is present in sodium tetraborate. Boron is an essential micronutrient for all plants, aiding in sugar transport and cell wall formation, but it is toxic in excess. The goal is to deliver a dose of boron high enough to be toxic to the weed, yet low enough for turfgrass to tolerate. This margin is narrow; too much boron will damage the entire lawn. Excess boron disrupts the weed’s metabolism, leading to yellowing, wilting, and ultimately the death of the plant.
Step-by-Step Borax Application Guide
The process begins with accurately measuring and dissolving the borax, which is critical due to the fine line between an effective dose and a damaging one. A common mixture suggests dissolving 10 ounces of household borax (e.g., 20 Mule Team Borax) in four ounces of warm water until fully dissolved. This concentrated mixture is then diluted into 2.5 gallons of water, creating a solution intended to cover 1,000 square feet of lawn area.
Before application, test your sprayer setup with plain water to measure your walking speed and spray pattern. This ensures you can evenly distribute the entire 2.5 gallons over the target 1,000 square feet. The solution must be applied as a broadcast spray over the infested area, not as a spot treatment, to maintain the correct concentration per square foot.
Application is most effective when Creeping Charlie is actively growing, typically in the spring, and when no rain is expected for at least 48 hours following treatment. Apply on a calm day to prevent overspray onto desirable garden plants, as boron damages any plant it contacts. Even coverage is paramount; walking too slowly or double-spraying concentrates the boron, increasing the risk of turfgrass injury. The goal is to lightly mist the weeds and surrounding soil. Because of the risk of soil buildup, this borax treatment should only be applied once per year for a maximum of two consecutive years.
Safety Protocols and Avoiding Lawn Damage
Borax is a salt, and its misuse can lead to significant lawn and environmental damage. Boron does not easily break down or dissipate in the soil, meaning excessive or repeated applications can lead to a toxic buildup, potentially sterilizing the soil so that no vegetation can grow in that area for a considerable time. Before treating the entire lawn, perform a small test application in an inconspicuous area to observe the turfgrass reaction after a week.
Protecting yourself requires wearing appropriate personal protective equipment, including gloves, eye protection, and long-sleeved clothing during mixing and spraying. Borax is toxic if ingested by humans or pets, with symptoms ranging from vomiting and diarrhea to more severe complications. Keep children and pets completely off the treated area until the solution has thoroughly dried on the foliage, minimizing the risk of accidental ingestion or contact.
Long-Term Management and Alternative Control Methods
While borax offers a short-term solution, long-term control of Creeping Charlie depends on improving turf health and cultural practices. The weed thrives in moist, shady, and often poorly drained areas, so altering these conditions is a primary defense. Simple adjustments include pruning tree limbs to increase sunlight penetration and improving soil drainage to reduce the damp conditions the weed favors.
Maintaining a healthy, dense lawn is the most effective way to outcompete the weed. This involves fertilizing appropriately and mowing at a taller height, typically between two and three and a half inches. A thick stand of turfgrass limits the weed’s access to light and nutrients, slowing its spread.
Alternative Control Methods
Alternative chemical control is available through selective commercial herbicides containing active ingredients like triclopyr or dicamba. These are formulated to target broadleaf weeds without harming turfgrass. Manual removal is also an option for small infestations, but it requires persistent effort to ensure all creeping stems and roots are pulled out.