Creeping Charlie (Glechoma hederacea), also known as Ground Ivy, is a persistent, low-growing perennial weed that invades lawns and garden beds across North America. Introduced from Europe as a groundcover, it has since become a problematic invasive species due to its aggressive growth habit. The plant forms dense, mat-like patches that compete with and choke out turfgrass and native flora. Understanding how this plant propagates is necessary for developing an effective management plan.
Primary Spread Mechanism: Vegetative Runners
The primary reason Creeping Charlie is so challenging to eliminate is its highly efficient method of vegetative reproduction through specialized stems called stolons. These stolons are above-ground runners that spread horizontally along the soil surface, rapidly colonizing new territory. The plant’s low-growing nature allows these runners to creep beneath the blades of turfgrass, where they are protected from mowing.
At various points along the stolon, known as nodes, the plant produces new, shallow root systems that anchor the stem to the soil. Once rooted, each node forms a new, genetically identical plant, called a ramet, which then begins to send out its own runners. This process quickly creates a dense, interconnected network of plants that can cover a large area, with individual runners sometimes growing over seven feet long. This aggressive, clonal expansion allows the weed to dominate available space, especially in moist, shady environments where turfgrass struggles to thrive.
Secondary Spread: Seed Production and Viability
While vegetative runners drive local spread, Creeping Charlie also uses sexual reproduction through seed production to establish itself in new, distant locations. The plant produces small, bluish-purple flowers, typically in the spring and early summer, which result in seed formation. Although vegetative propagation is the primary means, each flower can produce up to four nutlet seeds.
These seeds are generally small and inconspicuous, allowing for dispersal through several natural methods. Water runoff can easily carry the seeds to new areas, and they may also be moved by wind or small animals. Under ideal conditions, Creeping Charlie can produce approximately 8,000 seeds per plant annually. These seeds maintain a viability that can exceed 70% after one year in the soil. While less reliable for rapid area takeover than runners, this mechanism is important for introducing the weed to entirely new locations.
Accidental Spread Through Fragmentation
Human activity often unintentionally aids the spread of Creeping Charlie through the fragmentation of its stems and runners. The plant’s stolons and square stems are brittle and can be easily broken into small pieces during routine yard maintenance. Processes like mowing, raking, edging, or tilling the soil can chop the interconnected plant network into numerous segments.
Since the stems are capable of rooting at their nodes, even a small, detached fragment can establish a new, viable plant if it lands on moist soil. This characteristic means that contaminated lawn equipment, such as mowers or power rakes, can transport viable fragments from an infested area to a clean one. Improper disposal of yard waste, such as adding clippings containing fragments to a compost pile, also allows the weed to re-root and continue its growth cycle.
How Understanding Spread Informs Control
The unique mechanisms of spread directly influence the necessary strategies for effective control of Creeping Charlie. The aggressive, clonal spread via stolons necessitates the use of systemic control methods. These methods are designed to travel throughout the entire interconnected plant system, reaching the farthest root nodes. For manual removal, the interconnected nature of the runners means that incomplete hand-pulling, which leaves behind fragments or rooted nodes, will inevitably lead to regrowth.
Seed production highlights the importance of preventing the plant from flowering, which is achieved through timely application of pre-emergent products or early-season herbicide treatments. Preventing the establishment of new plants from seed helps contain the infestation within its current boundaries. The ease of spread through fragmentation dictates that all maintenance equipment used in an infested area must be meticulously cleaned before being used elsewhere. Furthermore, all removed plant material must be bagged and disposed of, rather than composted, to prevent re-rooting.