The sandspur (Cenchrus species) is a pervasive annual grassy weed in Florida, notorious for the painful, spiny burrs it produces. These sharp seed pods cling to clothing and pets, allowing the plant to spread rapidly across lawns and landscapes. Eliminating this nuisance requires a strategic, multi-phase approach that targets the plant at different stages of its life cycle. Understanding the sandspur’s biology and employing both non-chemical and chemical controls with precise timing helps homeowners reclaim their turf.
Understanding the Sandspur Life Cycle
The most common variety in Florida lawns is the Southern Sandbur, which behaves as a summer annual, completing its life cycle within a single growing season. Its aggressive nature is tied directly to the warm, sandy soils prevalent throughout the state. Germination begins in the spring when soil temperatures consistently reach 52°F to 55°F, typically occurring between late February and early April, depending on the region.
The plant grows through the late spring and summer months, often going unnoticed until it begins to flower. The problematic phase occurs from summer through early fall when the plant produces its characteristic spiny burs. Each bur contains multiple seeds, which are responsible for the plant’s spread and persistence. The parent plant dies with the first hard frost, but the dormant seeds remain viable in the soil, ready to restart the cycle the following spring.
Mechanical Removal and Cultural Prevention
Non-chemical control methods focus on physical removal and creating an environment that discourages sandspur growth. For small infestations, carefully pulling the plants by hand before the burrs develop is effective, but it is important to remove the entire root system. Using a thick pair of gloves is highly recommended to protect hands from the sharp spines of mature plants.
Once burrs have formed, a different mechanical approach is necessary to prevent reseeding. Dragging an old carpet remnant, blanket, or cloth across the infested area helps collect the spiny burrs. This technique reduces the seed bank in the soil, but the collected material must be disposed of carefully to prevent the seeds from spreading elsewhere.
The long-term strategy involves cultural practices that promote a dense, healthy turfgrass canopy, which naturally crowds out opportunistic weeds. Mowing at the proper height is one of the most effective non-chemical controls. Maintaining a higher cut on warm-season grasses like St. Augustine or Zoysia shades the soil, which inhibits sandspur seed germination.
Deep, infrequent watering encourages turfgrass roots to grow deeper, making the lawn more resilient against weed invasion. Conversely, thin or bare patches of grass, often caused by poor soil health or incorrect maintenance, are the conditions sandspurs exploit to establish themselves. Filling these bare spots with grass plugs or sod helps quickly eliminate the open ground sandspurs need to thrive.
Chemical Control: Pre-Emergent and Post-Emergent Solutions
Chemical control is most successful when timed correctly, making pre-emergent herbicides the preferred defense against future infestations. These products create a chemical barrier in the soil that prevents seeds from sprouting. Application must occur before the sandspur seeds germinate, generally when the soil temperature reaches 52°F to 55°F.
In central Florida, this window often falls between late February and mid-March, while northern parts of the state may see this timing slightly later. Common pre-emergent active ingredients include Pendimethalin and Dimension (dithiopyr). It is imperative to check the product label to ensure the chemical is compatible with the specific Florida turfgrass variety, such as St. Augustine, Zoysia, or Bermuda.
For existing, actively growing sandspur plants, a post-emergent herbicide is required, though this is less effective once burrs have formed. Sandspurs are monocots, just like lawn grasses, which makes selective control more difficult than controlling broadleaf weeds. Selective herbicides often contain active ingredients like Atrazine or a combination of 2,4-D, dicamba, and quinclorac. Atrazine is recommended for St. Augustine and Centipede lawns but should be used with caution in high heat. Non-selective herbicides like glyphosate will kill any plant they contact, including turfgrass, and should only be used for spot treatment in non-lawn areas. Always follow the manufacturer’s directions precisely regarding temperature restrictions and application rates to prevent injury to the lawn.