Sandspurs (genus Cenchrus) are a painful and persistent lawn pest, identified by their sharp, spiny burs that easily cling to clothing, pets, and skin. As a summer annual grass weed, sandspurs thrive in warm, sandy soils and quickly take over a thin or stressed lawn. Eradicating this nuisance requires a strategic, multi-step approach that targets the weed throughout its life cycle, combining physical removal and timed chemical applications.
Identifying the Sandspur Growth Cycle
Sandspurs are warm-season annual weeds that germinate, grow, set seed, and die within one growing season. Understanding this cycle is important for effective control. Germination typically begins in late spring or early summer when soil temperatures consistently reach 52°F to 55°F, with peak emergence happening as temperatures rise to 75°F.
The plant grows vegetatively in early summer, often blending in with turfgrass until it flowers. Sandspurs produce their characteristic spiny burs (seed pods) throughout the summer and early fall. Each bur contains protected seeds that can remain viable in the soil for several years. The plant dies back completely with the first hard frost, leaving the burs behind to spread seeds for the following year.
Non-Chemical Removal Methods
For small infestations or for homeowners preferring a chemical-free approach, manual removal is an immediate solution that prevents the current plants from setting more seed. Hand-pulling is most effective when the sandspur plants are young and have not yet produced hard burs. Always wear thick gloves to protect your hands from the spiny seed pods, and ensure you remove the entire root structure to prevent regrowth.
Another effective non-chemical strategy focuses on minimizing seed production. Regular, close mowing can reduce the number of seed heads produced, but this is only effective before the burs mature. Using a lawnmower with a bag attachment is recommended, as it captures the burs and prevents them from spreading across the lawn. For areas with heavy bur concentration, dragging an old, fibrous blanket or towel across the ground can physically lift and collect the spiny pods for disposal.
Strategic Herbicide Application
Chemical control for sandspurs involves a dual approach, using different products to target the weed at different stages of its life cycle. Pre-emergent herbicides are the foundation of a successful control program, as they prevent the sandspur seeds from germinating. These products must be applied in late winter or early spring, before the soil temperature consistently reaches 52°F, which triggers germination. Common active ingredients like pendimethalin or oryzalin can provide partial control.
If sandspurs have already sprouted, a post-emergent herbicide is necessary to kill the actively growing plants. These are most effective when applied early in the growing season, typically late May or June, when the sandspur seedlings are small. Once the plants mature and produce hard burs, post-emergent effectiveness drops significantly. Look for selective herbicides containing active ingredients like imazaquin or Celsius WG, which are formulated to kill the grassy weed while leaving the desirable turfgrass unharmed. Always confirm the herbicide is safe for your specific grass type, especially for sensitive turf like centipedegrass, before application.
Maintaining a Sandspur-Free Lawn
The most effective long-term defense against sandspurs is cultivating a dense, healthy lawn that naturally crowds out the weed. Sandspurs thrive in thin, stressed turf and sandy, bare patches of soil. Proper fertilization, especially in the spring and fall, encourages the turf to thicken and create a dense canopy that blocks sunlight from reaching the soil, inhibiting sandspur germination.
Watering deeply and infrequently encourages the turfgrass to develop deep, robust root systems, making it more resilient to stress and less hospitable to sandspurs. Overseeding thin areas with desirable turfgrass in the fall can further increase lawn density and reduce exposed soil. Adherence to these cultural practices will diminish the sandspur’s opportunity to establish itself, gradually reducing the population.