St. Augustine grass, a popular warm-season turfgrass, has runners that allow it to spread aggressively across a lawn. Valued for its broad, coarse blades, it forms a dense turf in warm, humid climates. This spreading mechanism helps the grass establish quickly and crowd out many common weeds. Understanding how these runners function is essential for successful management of this lawn type.
Understanding St. Augustine’s Stolons
The runners of St. Augustine grass are technically known as stolons, which are specialized, above-ground stems that grow horizontally along the soil surface. This defines the grass, setting it apart from species that rely on rhizomes, or underground runners, for lateral expansion. Stolon stems are thick, often appearing light green or whitish, and are visible creeping over the ground.
The primary function of the stolon is vegetative propagation, allowing the grass to reproduce without seed. At regular intervals along the stolon are nodes, which root downward into the soil and simultaneously produce new upright shoots and leaves. This continuous process creates an interconnected network, resulting in the dense turf St. Augustine grass is known for.
This growth habit allows the grass to spread rapidly, sometimes extending several inches per week during the peak season. The development of a new, genetically identical plant at each node ensures the lawn maintains a thick, uniform appearance. Since the grass lacks significant rhizome growth, all lateral spreading and recovery capacity is concentrated in these surface runners.
Managing Lateral Growth and Spread
The aggressive lateral growth of the stolons requires specific adjustments to routine lawn care to maintain the turf’s health and appearance. Mowing height is a factor in managing stolon activity and promoting a healthy lawn structure. St. Augustine grass performs best when consistently mowed at a high setting, generally between 3 and 4 inches.
Mowing at this height encourages vertical growth rather than excessive focus on new surface stolons that can become detached. Cutting too short, or scalping, exposes the stolons to direct sunlight and stresses the grass, making it susceptible to disease and thinning. Consistent mowing with a sharp blade prevents the runners from being ripped or torn, which damages the plant.
The rapid spread of the stolons makes frequent edging necessary, especially along sidewalks, driveways, and garden beds. Without regular trimming, the runners quickly extend over pavement or invade adjacent areas. The dense, interwoven nature of the stolons can contribute to the accumulation of thatch, a spongy layer of organic material. Excessive thatch inhibits water and nutrient penetration, often requiring periodic dethatching or aeration.
Using Stolons for Lawn Establishment and Repair
The growth structure of St. Augustine grass, which relies entirely on above-ground runners, dictates the most effective methods for establishing a new lawn or repairing damaged areas. Due to the lack of commercially viable seed, St. Augustine grass is propagated vegetatively, meaning it is planted using living plant material. This makes sodding and plugging the primary methods for installation.
Sodding involves laying large sections of mature turf, where the dense network of existing stolons provides immediate coverage. Plugging uses small, rooted sections of the grass placed strategically across the bare area. The stolons on these plugs then grow outward from each point, rapidly filling in the space between them.
The speed with which the runners fill gaps is a major benefit for repair. When a bare patch appears, planting a plug allows the surrounding stolons to quickly creep into the exposed soil, establishing new roots and shoots to create a seamless repair. This characteristic makes St. Augustine a reliable choice for achieving a lush, uniform lawn cover relatively quickly, especially compared to grasses that rely on slow-growing seedlings.