Lawn burweed (Soliva sessilis) is a low-growing, cool-season broadleaf weed often called spurweed or stickerweed. It quickly turns a comfortable lawn into a painful hazard by producing small, sharp, spine-tipped burrs in late spring and early summer. Understanding the plant’s life cycle is crucial for implementing timely removal and prevention strategies.
Identifying Burweed and Its Vulnerable Life Cycle
The burweed plant has a prostrate, branching growth habit that keeps it close to the ground, often blending into the turf. Its leaves are bright green, finely divided, and deeply lobed, giving them an appearance similar to parsley. These leaves are arranged in a basal rosette when young, which makes the plant inconspicuous during its primary growth period.
Burweed is classified as a winter annual weed, meaning its seeds germinate when soil temperatures cool in the fall, typically around October. It grows slowly and remains small throughout the winter months. As temperatures begin to rise in late winter or early spring, the plant rapidly matures and produces small, inconspicuous flowers in the leaf axils. These flowers then develop into the hard, painful burrs that contain the seeds for the next generation. The plant dies completely when summer temperatures reach approximately 90°F, but the painful burrs remain in the turf. Therefore, the period from late fall through early winter represents the most vulnerable time for control, before the burrs have formed.
Non-Chemical Removal Strategies
For small, isolated patches, manual removal is a practical, non-chemical control method. Hand-pulling is most effective in the fall or early winter when the plants are small seedlings and have not yet developed their extensive root systems. It is important to remove the entire root structure to prevent regrowth. This must be done before the spine-tipped burrs appear in the spring, as pulling the plant afterward will spread the seeds across the lawn.
Cultural controls can also suppress burweed growth, particularly in non-turf areas. Applying a thick layer of organic mulch in garden beds can block sunlight, thereby inhibiting the germination of burweed seeds in the fall. Horticultural vinegar (acetic acid) provides limited control over established burweed plants. It acts as a contact herbicide, primarily burning the above-ground foliage, but it often fails to kill the deep roots of a mature winter annual. This type of non-selective treatment may require multiple applications.
Effective Herbicide Applications
The most effective chemical approach involves using post-emergent broadleaf herbicides during the plant’s active growth phase. Look for products containing a combination of active ingredients such as 2,4-D, mecoprop (MCPP), and dicamba, often called a “three-way” herbicide. This combination targets broadleaf weeds without harming most established turfgrasses when applied correctly. Other effective options include herbicides containing metsulfuron or atrazine, though atrazine is limited to St. Augustinegrass and centipedegrass lawns.
The timing of application is paramount for success. Post-emergent herbicides should be applied from late fall through early winter (typically November through February) when the weed is small and actively growing. This window allows the chemical to kill the plant before it produces burrs in the spring. Applying the herbicide after burrs have formed in March or April will kill the plant, but the burrs will remain in the soil, defeating the purpose of eliminating the stickers.
Herbicide effectiveness is also strongly influenced by temperature. For optimal uptake and translocation within the weed, these products should be applied when air temperatures are above 40°F, as the plant must be actively metabolizing. For light infestations, spot treating individual plants is an efficient use of the product. For widespread issues, a broadcast application across the entire lawn may be necessary. Always follow the manufacturer’s label instructions precisely regarding application rates and safety precautions, especially when applying near ornamentals or specific turf types like St. Augustinegrass, which can be sensitive to certain ingredients.
Long-Term Prevention Through Lawn Health
The long-term strategy for preventing burweed relies on creating a dense, healthy turf that outcompetes the weed. Burweed thrives in weak, thin, or worn areas of a lawn where sunlight can easily reach the soil. A strong turf canopy physically blocks the light necessary for the burweed seeds to germinate in the fall.
Proper mowing height is a simple yet powerful preventative measure. Mowing at the higher end of the recommended range for your grass species, such as three inches for many warm-season grasses, encourages taller, denser growth. The resulting shade cast by the longer grass blades suppresses the germination of burweed seeds. Adhering to a correct fall fertilization schedule promotes vigorous growth of the desirable turf, helping it crowd out the newly germinating winter annuals.