Stepping on a sharp sticker in your lawn is often the first introduction many people have to the persistent weed known as Lawn Burweed or Spurweed (Soliva sessilis). This common winter annual is a nuisance because its small, low-growing form is inconspicuous until late spring. At that time, it produces hard, spine-tipped burs that make walking barefoot painful. Once these stickers have formed, the plant has set seed for the next year’s invasion. Controlling this weed effectively requires understanding its seasonal timing and applying targeted strategies to eliminate it before it can produce its spiny seeds.
Accurate Identification and Life Cycle
Lawn Burweed is easily recognized by its low, prostrate growth habit, often forming a flat mat close to the soil surface. Its leaves are bright green and finely divided, giving them a delicate, fern-like appearance. The plant starts as a basal rosette, and as it grows, it branches out.
This weed is classified as a cool-season annual. Seeds typically germinate in the fall, often around October, once nighttime temperatures consistently drop into the 55–60°F range. The plant remains small and actively grows throughout the cool winter months.
As temperatures warm in late winter or early spring, the burweed enters its reproductive phase, producing small, inconspicuous flowers. These flowers mature into the hardened, spine-tipped burs. The plant naturally dies off in late spring or early summer when air temperatures consistently reach approximately 90°F, leaving behind seeds ready to germinate the following fall.
Non-Chemical and Cultural Control Methods
Physical removal of burweed is most effective when the plants are small and have not yet produced seeds. Since the plant has a shallow, fibrous root system, individual plants can often be easily pulled from moist soil. However, manual removal is tedious with widespread infestations, and pulling plants after burrs have formed can scatter seeds, potentially worsening the problem.
Cultural practices focused on strengthening the turfgrass are the foundation of non-chemical prevention. A dense, healthy lawn naturally competes with burweed for sunlight, water, and nutrients, making establishment difficult. Mowing the turfgrass at the upper limit of its recommended height encourages thicker growth, which helps shade the soil and discourage weed germination. Proper watering is also important; deep, infrequent irrigation encourages strong, deep roots, while light, daily watering favors shallow-rooted weeds. Raking up fallen leaves prevents excessive moisture buildup and turf thinning, which favor burweed establishment.
Chemical Control Strategies
Chemical control depends on precise timing to eliminate the plant before the burs harden. The most effective strategy involves applying post-emergent broadleaf herbicides during late fall or winter when the weed is small and actively growing. This period typically ranges from December through February, well before the plant begins to form its spine-tipped seeds.
A number of specific active ingredients are effective against Soliva sessilis. Look for products containing three-way herbicide combinations, which typically include 2,4-D, Dicamba, and MCPP (Mecoprop). These herbicides are generally safe for most common turfgrass varieties, though reduced rates may be necessary for sensitive grasses like St. Augustinegrass and Centipedegrass to prevent damage.
Post-Emergent Active Ingredients
- Metsulfuron
- Simazine
- Thiencarbazone, Iodosulfuron, and Dicamba combinations
- 2,4-D, Dicamba, and MCPP combinations
For the chemical application to be successful, the weed must be actively metabolizing; therefore, application on a sunny day when temperatures are above 50°F is recommended. A second application, spaced according to the product label (often 10–14 days later), may be necessary to control all emerging plants.
Alternatively, a pre-emergent herbicide can be applied in the fall to prevent seeds from germinating. Products containing active ingredients like Isoxaben, Prodiamine, Dithiopyr, or Atrazine are commonly used for this purpose. The application window for pre-emergents is generally late September to October, coinciding with the drop in soil temperatures that signals burweed seeds to germinate.
Pre-Emergent Active Ingredients
- Isoxaben
- Prodiamine
- Dithiopyr
- Atrazine
If using a post-emergent product in winter, consider one that also has pre-emergent properties, like Atrazine, to manage any seeds that may germinate later.
Long-Term Prevention of Reinfestation
Achieving a lawn environment that resists burweed requires a commitment to annual maintenance practices beyond just chemical application. Addressing the underlying conditions that allowed the weed to establish is important, since burweed thrives in stressed, thin, or bare areas of turf. A soil test helps identify and correct nutrient deficiencies or improper soil pH levels that might be inhibiting healthy turf growth.
Overseeding the lawn, especially in the fall, is one of the most effective preventative measures. By introducing new grass seed, you increase the density of the turf, closing the gaps where the burweed seeds would otherwise germinate. This strategy, combined with proper fertilization, promotes a vigorous canopy that physically crowds out the low-growing annual weed.
Consistent follow-up is important because burweed seeds can remain dormant in the soil for extended periods. Integrating pre-emergent herbicide applications in the fall with a program of cultural practices creates a two-pronged defense. This annual cycle of thickening the turf and strategically applying controls ensures that the weed population is suppressed year after year, reducing the likelihood of reinfestation.