Creeping Charlie (Glechoma hederacea) is a common, aggressive weed that invades lawns and garden beds, known for its distinctive scalloped leaves and low-growing, mat-forming habit. Creeping Charlie does not die in the winter; it is a hardy perennial plant that lives for more than two years and returns each season. It has developed several mechanisms that allow it to successfully overwinter, ensuring its survival even in freezing temperatures.
Creeping Charlie’s Winter Survival Mechanisms
Creeping Charlie is an herbaceous perennial, allowing its root system and crown to persist underground through cold weather, unlike annual weeds. Its structure is suited for cold tolerance, starting with its low-growing nature. This ground-hugging habit provides insulation, often protected by snow cover, which shields the plant from temperature fluctuations.
Below the soil surface, the plant relies on a network of creeping stems (stolons) and underground stems (rhizomes). These structures are packed with stored energy reserves, acting as a protected food supply that fuels the plant’s survival through dormancy. In milder climates, creeping Charlie may remain semi-evergreen, retaining green leaves that can photosynthesize during warm spells, bolstering its energy stores. This combination of protected energy reserves and low-profile growth ensures the plant crown avoids freezing.
The Role of Winter Survival in Spring Aggression
Because it survives the winter intact, creeping Charlie gains a competitive advantage over turfgrass in the early spring. Unlike grasses or weeds that must restart from seed, this perennial weed does not need to restart its life cycle. The energy stored in the stolons and rhizomes immediately fuels rapid lateral expansion as soon as temperatures rise.
This head start allows the plant to quickly establish dense, mat-like patches that smother emerging turfgrass. The surviving runners put down new roots at every node they contact the soil, rapidly establishing new plants and expanding the infestation. This aggressive growth pattern, fueled by successful winter survival, makes it difficult to manage and eradicate.
Timing Control Measures for Effective Eradication
Controlling creeping Charlie is challenging due to its perennial nature, but success requires timing herbicide applications to exploit the plant’s natural life cycle. The most effective time to apply systemic herbicides is in the late fall, after the first light frost but before a hard freeze. During this period, the plant begins winter preparation, actively drawing nutrients and carbohydrates from its leaves down into its root system for storage.
A systemic, broadleaf weed killer containing active ingredients like triclopyr or dicamba is absorbed by the leaves and is then translocated down to the roots with the plant’s food supply. This poisons the entire plant, including the underground stolons and rhizomes, which are the source of next year’s growth. A second effective time for application is in the early spring when the plant is actively growing and flowering, as it is vigorously moving materials through its system.
Treatments applied during the peak heat of summer are less effective because the plant’s metabolism slows down, reducing the rate it draws the herbicide into its root structure. The goal is to treat the plant when it is actively moving materials, either preparing for winter dormancy or during its initial spring growth surge. Following a fall treatment with a spring application, targeting new growth, provides the best chance for eradication.