Vinca minor, commonly known as periwinkle or creeping myrtle, is a non-native evergreen groundcover appreciated for its glossy foliage and blue-purple flowers that bloom in the spring. Introduced to North America from Europe and Western Asia in the 1700s as an ornamental plant, it remains a popular commercial choice for difficult-to-plant shady areas. While it is not federally listed as invasive in all regions, it exhibits an aggressive growth habit and is classified as an invasive species across much of the eastern United States and other locales where it has escaped cultivation. Its unchecked spread into natural ecosystems and garden beds presents a significant ecological and maintenance problem.
Defining Aggressive Growth and Spread Mechanisms
The plant’s invasive success is linked to its primary method of reproduction, which is almost entirely vegetative. Vinca minor is a trailing vine that relies on stolons, or runners, which are horizontal stems that creep along the soil surface. These runners root wherever a node touches the ground, establishing a new, independent plant that is genetically identical to the parent.
Rooting at the nodes allows periwinkle to expand rapidly, forming a dense, thick mat of foliage and stems. The resulting carpet can be several inches deep and is difficult to penetrate or disturb. Its high tolerance for deep shade gives it a considerable advantage in forested areas where many native ground covers cannot compete for light. This aggressive, mat-forming habit allows it to spread rapidly from initial plantings, often escaping from old homesites and gardens into adjacent natural areas.
Environmental and Garden Impact
Once established, the dense, low-growing mats of Vinca minor pose a severe threat to local plant biodiversity. The plant smothers native ground flora and prevents sunlight from reaching the soil, effectively shading out the seedlings of both native wildflowers and woody species. This displacement results in a monoculture, where periwinkle becomes the sole plant species covering the forest floor.
Ecological studies suggest that the plant may exhibit allelopathic properties, meaning it produces biochemicals that inhibit the germination and growth of other species. This chemical warfare, combined with its ability to monopolize space and moisture, significantly alters the natural composition of the invaded habitat. In a garden setting, the dense mat makes planting new, desired species nearly impossible, and the labor required for removal or containment represents a major practical difficulty for gardeners.
Management and Control Methods
Controlling established Vinca minor requires a persistent, multi-year approach due to its extensive root system and ability to resprout from fragments. For small infestations, manual removal is a feasible option, but it is necessary to dig up the entire root mass and all trailing runners. Because the plant can regenerate from even small root sections, any material removed should be disposed of in the trash, not composted, to prevent further spread.
For larger, widespread infestations, a combination of methods is the most effective strategy. Smothering the area through solarization involves covering the periwinkle with a thick, opaque tarp or layer of cardboard for a minimum period of four to six months. This deprives the plants of light, depleting the energy stored in the roots and eventually killing the vegetation.
Chemical control options, such as systemic herbicides containing glyphosate or triclopyr, can be applied to the foliage, especially in late summer or early fall when the plant is moving nutrients to its roots. Due to the plant’s thick, waxy leaves, which can shed water-based sprays, some experts recommend mowing or cutting the foliage back first to encourage fresh, more vulnerable regrowth before herbicide application. Regardless of the method chosen, consistent monitoring is necessary, as follow-up treatments will be required to manage regrowth from residual root fragments.