Vinca, commonly known as periwinkle, is a popular ornamental groundcover used in landscaping due to its ability to form a dense mat of evergreen foliage and produce attractive blue or purple flowers. Vinca definitely spreads, and its vigorous creeping habit is why it is often selected for covering large, shaded areas. This characteristic growth pattern, however, also presents a challenge for many gardeners, as the plant can easily extend beyond its intended boundaries. Managing its spread requires understanding the biological mechanisms behind its growth and the differences between the common varieties.
The Biological Mechanism of Vinca’s Spread
The primary method by which Vinca plants expand is through vegetative reproduction, not seeds. The plant develops long, trailing stems, called runners or stolons, that extend horizontally across the soil surface. These stems are equipped with nodes, which are points where leaves and buds emerge.
When a node contacts moist soil, it spontaneously develops new roots. This rooting process establishes an independent, genetically identical plantlet that remains connected to the parent, creating a widening, interconnected patch. This rapid rooting strategy is the plant’s most effective means of colonization, as it rarely relies on seed production. This self-propagation allows Vinca to quickly cover ground and control erosion. However, any segment of stem with a node can potentially start a new colony, meaning discarded plant fragments can easily take root in new locations.
Understanding the Aggressiveness of Vinca Varieties
The level of aggressiveness depends heavily on the specific species planted and the geographic location. The two most common perennial types are Vinca minor (Dwarf Periwinkle) and Vinca major (Bigleaf Periwinkle), which exhibit distinct growth behaviors. Both are trailing, evergreen perennials, but Vinca major is significantly more vigorous and less cold-hardy, thriving in warmer climates.
Vinca major produces longer, arching stems and has larger leaves and flowers, contributing to its greater spreading capacity. It is frequently classified as an invasive species in many regions because its rapid growth quickly outcompetes and displaces native vegetation. Vinca minor is the more cold-hardy option and is generally considered more manageable, though it remains an aggressive spreader. While its spread is slower, Vinca minor is still listed as invasive in numerous states across the midwestern and northeastern United States.
Essential Strategies for Controlling Unwanted Spread
Managing Vinca’s aggressive spread requires consistent monitoring and a combination of physical control methods. For containing an existing patch, install a physical barrier, such as landscape edging or plastic, buried at least six inches deep around the area. This creates a below-ground obstacle that prevents runners from rooting outside the desired boundary.
Regular pruning is another effective strategy, as it directly removes the stolons before they can establish new roots. Trimming the peripheral runners routinely helps maintain a neat edge and prevents encroachment into other garden beds. It is crucial to remove the cut stems from the ground, as any detached piece with a node can potentially root and start a new plant.
For complete removal of a large, unwanted area, methods like digging and smothering can be employed. Manual removal involves carefully digging out the entire network of vines and roots, ensuring that no fragments are left behind. Alternatively, smothering the patch with an opaque material, such as thick cardboard followed by a layer of mulch, blocks sunlight. This light deprivation depletes the plant’s energy reserves, causing the extensive root system to die off over time.