Violets (Viola) are common perennial ground cover plants known for their heart-shaped leaves and ability to thrive in many conditions. Gardeners recognize their vigorous spreading nature, which allows them to quickly establish dense colonies across lawns or garden beds. This persistent growth habit results from a highly successful dual reproductive strategy. Understanding how violets reproduce is the first step in managing them in your landscape.
The Two Primary Ways Violets Spread
Violets employ two primary mechanisms for propagation, making them effective at colonizing new territory and sustaining existing patches. The first method is vegetative, relying on subterranean growth structures known as rhizomes. These fleshy, horizontal underground stems store energy and produce new, genetically identical shoots at intervals, creating a connected network of plants. Since the rhizomes are tough, severing the top growth is often ineffective, as the underground portion retains the ability to rapidly produce new foliage.
The second strategy involves seed production and dispersal through two different types of flowers. Showy, purple, or white flowers appearing in early spring are chasmogamous flowers; these open and rely on insects for cross-pollination. However, many violet species produce the majority of viable seeds from small, inconspicuous flowers that never open, known as cleistogamous flowers. These closed flowers are self-pollinating, guaranteeing seed production even without insects or favorable weather.
The seeds are often scattered through explosive dehiscence, where the drying seed capsule builds up pressure and forcibly ejects the seeds several feet away. Violets also utilize ants for secondary dispersal, a process called myrmecochory. The seeds possess a fatty, protein-rich appendage called an elaiosome, which attracts ants that carry the seed away, consume the appendage, and discard the seed in a new location.
Are Your Violets Native or Invasive
Whether a violet is considered a desirable wildflower or an aggressive weed depends on the region and the specific species present. Many common spreading types, such as the common blue violet (Viola sororia), are native to North America. These native violets are valuable groundcovers in woodland or naturalized areas, serving as important early-season food sources for pollinators and host plants for certain butterfly larvae.
The perception of violets as “invasive” usually stems from their tenacious ability to outcompete turfgrass and ornamental plants in a manicured setting. The vigorous spreading that is ecologically useful in a natural habitat becomes a problem for homeowners seeking a grass monoculture. While ornamental varieties are often bred to be less aggressive, any violet species can aggressively colonize an area if the soil conditions are favorable.
Strategies for Controlling Violet Growth
Controlling established violet colonies requires a multi-pronged approach because of the plant’s strong rhizome system and waxy leaves. Cultural practices should be the first line of defense, focusing on improving the health and density of your lawn to suppress weed growth. Violets thrive in moist, fertile, and often shady conditions. Raising your mower height and avoiding over-watering makes the area less hospitable. A thick, healthy turfgrass canopy naturally crowds out the low-growing violet foliage, starving the plant of necessary sunlight.
For small patches or garden beds, physical removal can be effective, but it requires diligent effort to remove the entire root structure. Since the plant has a fibrous root system anchored by tough rhizomes, simply cutting the top encourages new growth. You must dig deep to remove all the fleshy rhizomes; otherwise, the plant will quickly regenerate from fragments left behind. This method is most practical when the soil is moist, allowing for easier extraction of the connected root mass.
When cultural and physical methods prove insufficient, chemical control may be necessary, though violets are resistant to many herbicides. The most effective products are selective broadleaf weed killers containing the active ingredient triclopyr. Due to the violet’s thick, waxy leaf cuticle, it is helpful to add a surfactant, such as a drop of dish soap, to the herbicide mixture to help the chemical adhere and be absorbed.
Timing is important for successful chemical application, with the best results achieved in the fall. During autumn, the violet plant is actively moving nutrients down to its root system in preparation for winter dormancy. Applying the herbicide then allows the chemical to be effectively translocated into the rhizomes, killing the plant at the root level. Multiple applications over several years may be necessary to achieve full control due to the plant’s resilience and extensive seed bank.