Creeping Jenny (Lysimachia nummularia) is a perennial groundcover native to Europe and temperate Asia. Gardeners often select it for its vibrant, low-growing foliage and rapid spread, valuing its ability to quickly fill in difficult landscaping areas. Its popular golden-leaved cultivar, ‘Aurea,’ is prized for adding color or cascading from containers. However, the plant’s vigorous growth has led to questions about whether this aggressive nature qualifies it as an invasive species.
Distinguishing Aggressive Growth from True Invasiveness
A plant that is merely aggressive spreads quickly and vigorously within a garden setting, often outcompeting nearby ornamental species for resources. Gardeners commonly refer to these plants as “garden thugs” because their rapid expansion makes them difficult to manage in a cultivated space. An invasive species, in contrast, must meet two specific criteria: it must be non-native to the local ecosystem, and its introduction must cause environmental or economic harm. This harm typically involves displacing native plants, disrupting local food webs, or altering the natural function of an ecosystem.
Creeping Jenny’s classification often depends heavily on the specific region. In many areas, it is simply an aggressive garden plant that requires frequent management. However, the species is officially recognized as an invasive threat in many parts of the United States, particularly in wetlands, moist forests, and along stream banks. Some regulatory bodies classify the standard green species as restricted due to its environmental threat, while the less vigorous ‘Aurea’ cultivar is often exempt.
The Growth Habits That Make Creeping Jenny a Threat
The plant’s success in spreading and forming dense colonies is due to its highly effective vegetative reproduction. Creeping Jenny produces long, trailing stems, known as stolons, which creep along the soil surface. Wherever the leaf nodes on these stems touch the ground, they quickly form slender fibrous roots, establishing a new, independent plantlet. This ability to root at every node allows the plant to rapidly colonize a large area through a network of connected stems, making it extremely difficult to fully remove.
This vegetative spread is compounded by the plant’s adaptability to a wide range of growing conditions, enabling it to outcompete less hardy native flora. It thrives in consistently moist or even wet soils, such as those found in floodplains and along waterways. Furthermore, it tolerates a broad spectrum of light exposure, from full sun to partial shade, giving it an advantage in various habitats. Once established, its low-growing habit, typically only two to four inches tall, forms a thick, dense mat that effectively smothers and shades out seedlings and desirable native herbs beneath it.
Strategies for Controlling and Removing Creeping Jenny
Controlling the spread of Creeping Jenny requires consistent effort and often a combination of methods tailored to the size of the infestation. For small, isolated patches, manual removal is the initial and most direct approach, but it must be done with meticulous attention to detail. Every single stem and root fragment must be pulled or dug out, as any piece left behind can quickly re-root and regenerate a new plant. The roots are relatively shallow, making it possible to use a flat spade to cut and lift the entire mat, but the extensive network of runners makes this a tedious process.
Cultural Controls
Cultural controls focus on limiting the plant’s access to light and space, which can be effective following manual removal. Since the plant is low-growing, mowing is largely ineffective because its leaves are not clipped. After clearing an area, applying a thick layer of organic mulch or covering the soil with black plastic can suppress regrowth by starving any remaining fragments of light. To prevent future lateral spread into garden beds, physical barriers like deep edging can be installed, or the plant can be kept exclusively in containers or hanging baskets where its trailing stems are safely suspended.
Chemical Control
When infestations are large or deeply established, chemical control may be the most viable option, often requiring application over two growing seasons for complete eradication. Herbicides formulated for broadleaf weeds, such as those containing glyphosate or triclopyr, are generally effective against Creeping Jenny. These chemicals should be applied as a targeted spot treatment, ensuring careful application to minimize damage to surrounding desirable plants. If the plant is growing near water bodies, which is a common habitat, it is necessary to use an aquatic-safe formulation of the selected herbicide.