The sudden appearance of small purple flowers dotting a lawn is a common phenomenon that sparks curiosity, and often frustration, among homeowners. These low-growing plants are typically persistent perennial or annual weeds that thrive in turfgrass, especially in areas where the grass is thin or weakened. While they may offer a brief splash of color, their aggressive nature and ability to spread quickly often make them unwelcome invaders. Understanding the specific type of plant you are dealing with is the first step toward effective management.
The Most Common Purple Lawn Invaders
One of the most widespread culprits is Ground Ivy, also known as Creeping Charlie (Glechoma hederacea), a perennial member of the mint family. This plant forms dense, low mats with round to kidney-shaped leaves that have scalloped edges, producing small, funnel-shaped blue-purple flowers in the spring. Ground Ivy spreads relentlessly by seeds and by long, creeping stems (stolons) that root at every node they touch.
Another common invader is Henbit (Lamium amplexicaule), a winter annual that germinates in the fall and flowers early in the spring. Henbit is characterized by its square stems and tiny, pinkish-purple, tubular flowers that grow in whorls around the upper parts of the stem. The leaves are rounded and deeply lobed, and the upper leaves appear to clasp the main stem.
Wild Violets (Viola sororia) are a native perennial often found in lawns. These plants are easily identified by their distinct heart-shaped leaves and their five-petaled, dark blue to purple flowers that appear on leafless stalks. Violets spread by both underground rhizomes and by seeds that are forcibly ejected from their pods, forming tenacious patches.
Self-Heal (Prunella vulgaris), a low-growing perennial that also belongs to the mint family, produces dense, upright spikes of small, tubular purple flowers that bloom from summer into fall. This plant forms mats through creeping stems that root at the nodes, but its dense, club-like flower head distinguishes it from the others.
Key Differences for Positive Identification
The stem structure is one of the most reliable indicators, as Ground Ivy, Henbit, and Self-Heal all possess the square stem characteristic of the mint family. In contrast, Wild Violets lack a true above-ground stem, with both their leaves and flowers emerging directly from the base of the plant.
Leaf attachment and shape provide clear distinctions. Henbit is unique because its upper leaves have no stalks, attaching directly to the stem and appearing to clasp it. Ground Ivy leaves are kidney-shaped with scalloped edges and attach to the creeping stem via long stalks (petioles). Wild Violets stand out with their distinct, often glossy, heart-shaped leaves that are clustered near the soil surface.
The growth habit and odor can confirm the species. Ground Ivy is a low-spreading creeper that emits a distinct, minty smell when its leaves are crushed or mowed. Henbit, despite its low stature, is an annual that grows upright from a central root. Wild Violets are perennial plants that form clumps and spread via underground rhizomes.
Weed or Wildflower: Assessing the Impact
All of these purple-flowered species serve as an early source of nectar for pollinators, such as honeybees and bumblebees, emerging in the early spring when other food sources are scarce. For those prioritizing biodiversity, these plants offer a benefit to local insect populations.
The negative impacts relate to their competitive nature within a turfgrass environment. Ground Ivy and Wild Violets are tenacious perennial plants that spread by seed and underground structures, allowing them to smother and displace turfgrass. The dense mats they form steal light, water, and nutrients from the surrounding grass, leading to bare patches.
For property owners with livestock, Ground Ivy presents a specific risk, as it is considered mildly toxic to horses and goats. Though its bitter taste generally deters grazing, consumption of large quantities, especially when dried in hay, can lead to negative symptoms.
Control and Removal Strategies
Effective management requires an approach that focuses on improving the health of the turf. Cultural control is the first line of defense, involving practices like mowing the lawn at the highest setting and correcting poor soil drainage. Maintaining a dense, vigorous stand of grass is the best way to naturally suppress weed growth, as healthy turf out-competes weeds for resources and space.
Mechanical removal, such as hand-pulling, is generally only successful for small, isolated patches and winter annuals like Henbit. For perennial invaders like Ground Ivy and Wild Violets, hand removal is often ineffective because their extensive rhizomes or runners are left behind, allowing the plant to quickly regenerate. Organic treatments like horticultural vinegar can scorch and kill the visible foliage.
The non-selective nature of vinegar means it will also damage the surrounding turf, and it rarely penetrates deep enough to kill the robust root systems of perennial weeds. Chemical control offers the most effective solution for widespread infestations, utilizing selective broadleaf herbicides containing active ingredients like triclopyr or dicamba. The most effective time to apply these products for perennial weeds is late fall, as the plant transports nutrients to its roots for winter storage, carrying the herbicide down with them. Due to the waxy coating on Wild Violet leaves, a liquid application is preferred over granular products.