Creeping Charlie, scientifically known as Glechoma hederacea, is an aggressive perennial plant and invasive ground cover that quickly forms dense mats in turf and landscape beds. This European native was introduced to North America centuries ago, and its vigorous growth habit makes it a challenge to manage once established. It generally produces small, distinctive purplish-blue or lavender blooms.
Key Features for Positive Identification
Identifying Glechoma hederacea is possible by examining its vegetative structure. The leaves are bright, glossy green, rounded to kidney-shaped, and have deeply scalloped margins. They grow in an opposite arrangement and release a recognizable, musky mint-like odor when crushed.
The stem structure provides a definitive clue: it is square or four-sided, a trait shared by all members of the Lamiaceae family. This plant spreads rapidly across the ground using above-ground runners, called stolons, which root at every node where they touch the soil, creating thick, low-growing mats.
Detailed Look at the Bloom
The flowers of Creeping Charlie are a small feature, appearing in the spring and early summer, typically from April into June. The color ranges from light lavender or blue-violet to purplish-blue.
Each flower is tubular and approximately one-half inch long, displaying a two-lipped structure characteristic of mint plants. The flowers emerge in small clusters, or whorls, of two to seven blossoms in the leaf axils on the upper portion of the stem. The lower lip may feature darker spots or lines that serve as nectar guides for visiting insects.
Effective Management Strategies
Managing established Creeping Charlie requires an integrated approach due to its extensive creeping root system and ability to root at every stem node. For small, isolated patches, mechanical removal is an option, provided every piece of the stolon and root is meticulously pulled from the soil. Leaving even small stem fragments behind allows the plant to quickly regenerate.
Cultural Control
Cultural control focuses on making the environment less favorable for the weed, which thrives in shaded, moist, and nutrient-poor soils. Improving lawn health by aerating compacted soil, ensuring proper drainage, and fertilizing appropriately can help the desirable turfgrass outcompete the weed. Pruning overhead trees to increase light penetration to the lawn surface also discourages its spread.
Chemical Control
For widespread infestations, chemical control using post-emergence broadleaf herbicides is necessary. Products containing the active ingredient triclopyr are the most effective for controlling this specific weed. Herbicides that combine triclopyr with other compounds like dicamba or MCPP are highly effective formulations.
The timing of application is a significant factor in successful chemical management. The most effective period is the fall, from mid to late autumn. During this time, the plant is naturally moving nutrients down to its root system for winter storage, and the herbicide is efficiently translocated deep into the roots, leading to better eradication. A second application in the spring, ideally when the plant is in bloom, can further improve control.