Horseherb, scientifically known as Calyptocarpus vialis, is a common, low-growing plant found in various landscapes, particularly in warmer regions. This perennial herb is prevalent in diverse settings, including lawns, gardens, and natural areas. Native to southern coastal states of the U.S. and Mexico, it has spread globally.
Identifying Horseherb
Its leaves are typically small, dime-sized, and range from oval to heart-shaped. These medium-green leaves have serrated edges and are arranged oppositely along the stems. The foliage often has a slightly hairy texture.
Small, yellow, daisy-like flowers are a prominent feature, usually measuring between 5-10 millimeters across. These delicate blooms generally have 4-5 petals and can appear from spring through fall, and even year-round in frost-free climates. The plant exhibits a low-growing, creeping habit, typically reaching a height of 6-12 inches. It forms dense mats as its thin stems sprawl across the ground, rooting at the nodes where they touch the soil, contributing to its rapid spread.
Horseherb in Your Landscape
Horseherb presents a dual nature in garden and lawn settings, perceived as either a beneficial groundcover or a persistent weed. When intentionally cultivated, it offers several advantages. It demonstrates high drought and heat tolerance, requiring low to medium water use once established, making it a sustainable choice. This plant performs well in full sun, part shade, or even full shade, adapting to various light conditions.
Horseherb forms a dense mat that can suppress weeds and withstand moderate foot traffic, offering a low-maintenance alternative to lawns, especially in shady or sloped areas. Its ability to attract small butterflies, such as sulfurs and skippers, adds ecological value. Conversely, horseherb is often considered a nuisance due to its aggressive spreading habit via seeds and runners. It can outcompete desired plants in garden beds and readily invades manicured lawns, particularly in thin or disturbed areas. This rapid proliferation can lead to a more homogenous landscape, reducing plant diversity.
Managing Horseherb
Managing horseherb depends on whether the goal is to control its spread or encourage its growth.
Manual and Cultural Control
For those seeking to reduce or eliminate horseherb, manual removal is an option. Hand-pulling or digging works best after a good rain when the soil is moist, ensuring as much of the root system as possible is removed to prevent resprouting.
Cultural practices can also help suppress its growth. Applying a thick layer of mulch in garden beds can deter horseherb from establishing itself. Improving soil health and favoring desired plants can also limit horseherb’s dominance.
Chemical Control
Chemical options are available for more widespread control, typically involving selective broadleaf herbicides. Products containing ingredients like atrazine or those designed for broadleaf weed control in warm-season grasses can be effective. Applying a pre-emergent herbicide in early spring can help prevent new horseherb plants from sprouting from seed.
Cultivating Horseherb
If the aim is to cultivate horseherb as a groundcover, minimal care is needed. Allowing it to spread naturally will create a lush, green carpet that tolerates mowing, which can be done every four weeks to maintain a neat appearance. Horseherb is well-suited for shady, sloped areas or as a low-water-use lawn alternative. Propagation is easily achieved through root division or by spreading clippings containing seeds onto desired areas.