Kidney weed, Dichondra repens, is a widespread perennial herb often encountered in various garden and landscape settings. This low-growing plant is recognized for its ability to form a dense, mat-like groundcover, frequently appearing in lawns, woodlands, and open grassy areas. While it can be intentionally cultivated as a lawn substitute in some regions, its vigorous growth often leads to it being considered a persistent weed in traditional turfgrass and garden beds.
Identifying Kidney Weed
Accurate identification of kidney weed begins with its distinctive foliage. The leaves are typically kidney-shaped to nearly circular, measuring approximately 5 to 25 millimeters long and 5 to 30 millimeters wide. These small green leaves feature a heart-shaped base and a rounded or slightly notched apex. The leaves are covered with soft, grayish hairs. The leaf stalks, or petioles, are often noticeably longer than the leaf blades themselves.
The growth habit of kidney weed is another key identifier. It is a creeping perennial that forms a thick, dense mat, typically remaining very low to the ground, usually not exceeding 5 centimeters in height. Its stems readily root at the nodes wherever they touch the soil, allowing the plant to spread horizontally and colonize new areas effectively. Small, inconspicuous flowers, ranging from greenish-yellow to pale yellow or white, can appear throughout the year. These solitary flowers are tiny, measuring only about 2.5 to 6 millimeters in length.
Why Kidney Weed is a Garden Problem
Kidney weed’s vigorous, creeping growth habit makes it a challenging presence in cultivated landscapes. It spreads rapidly by rooting at its nodes, allowing it to quickly colonize open ground and form dense mats. This aggressive spread enables it to outcompete desired turfgrass and garden plants for essential resources like sunlight, water, and nutrients. The thick carpet it forms can effectively smother existing grass, leading to bare patches or an uneven lawn texture.
The plant acts as an opportunistic species, readily filling any gaps or weak spots within a lawn or garden bed. Once established, its extensive network of rooted stems can make it particularly difficult to eradicate. This persistent nature detracts from the uniform appearance of a manicured lawn and compromises the health of surrounding vegetation. Small patches can rapidly become significant infestations if left unmanaged.
Effective Control Strategies
Managing kidney weed requires a combination of approaches to achieve lasting results. For smaller infestations, manual removal can be effective. Hand-pulling individual plants is most successful when the soil is moist, allowing for easier extraction of the entire root system. Since kidney weed roots readily at its nodes, it is important to remove all stem fragments to prevent re-establishment. Dispose of pulled plants away from the garden to prevent re-rooting.
Cultural controls play a significant role in weakening and discouraging kidney weed. Promoting overall soil health supports robust growth of desired plants, enabling them to outcompete weeds. This involves ensuring good soil structure and balanced nutrients. Proper watering practices, such as deep and infrequent irrigation, are also beneficial. Allow the soil surface to dry slightly between waterings to help prevent issues that weaken desired plants.
Applying a thick layer of organic mulch, approximately 3 to 4 inches deep, can effectively suppress kidney weed by blocking sunlight from reaching the soil surface, thus preventing seed germination. Mulch also adds organic matter, improving soil health over time. For lawns, maintaining a dense, healthy turf shades the soil and outcompetes weeds for resources.
For larger or more persistent infestations, chemical options may be considered. Post-emergent herbicides are applied directly to actively growing kidney weed and are most effective when the plants are young. Selective herbicides are available that target broadleaf weeds like kidney weed without harming most turfgrass species. Always check product labels for compatibility with your specific lawn type. When applying, thoroughly coat the leaves without causing runoff. Multiple applications, typically spaced two to four weeks apart, may be necessary for complete control.
Preventing Future Infestations
Long-term prevention of kidney weed focuses on creating an environment unfavorable for its growth and establishment. Implementing proper lawn care practices is a significant deterrent. Maintaining a taller mowing height, generally between 3 to 4 inches, promotes a denser lawn canopy. This makes it more difficult for kidney weed to establish. A taller lawn encourages deeper root growth, enhancing the turf’s natural competitiveness.
Regular and appropriate fertilization also contributes to a healthy, vigorous lawn that is more resistant to weed invasion. Providing necessary nutrients helps desired turfgrass grow densely, leaving fewer opportunities for kidney weed to take hold. Maintaining healthy soil through the addition of organic matter, such as compost, improves soil structure and fertility, further supporting the growth of strong, competitive plants.
Consistent monitoring of garden beds and lawns for any new kidney weed growth allows for early intervention. Addressing small patches promptly through hand-pulling or spot treatments can prevent them from spreading into larger, more challenging infestations. In areas with a history of kidney weed problems, applying pre-emergent herbicides can also provide a preventative barrier by inhibiting seed germination. Carefully follow product instructions and ensure compatibility with any existing desired plants.