When a lawn is described as “thick,” the term refers to turf that appears lush and dense, characterized by a high number of grass blades growing closely together. This quality is sought after in landscaping for its robust, carpet-like appearance. The specific name for this condition depends on whether one is referring to the physical structure, the species of grass, or the texture of the individual blades. Understanding the elements that create this density helps identify the source of the lawn’s fullness.
Common Terms for Dense Turf Structure
The most precise term for a dense, surface layer of grass is turfgrass, which is any grass species forming a uniform, continuous cover on the ground. When this vegetative layer is harvested with a thin layer of soil and roots attached for transplantation, it is called sod. Sod represents a pre-grown, highly dense piece of turf.
A dense grouping of grass, particularly when discussing its collective growth habit, is often referred to as a stand or a mat. The term “mat” describes the thick, interwoven network of roots, stems, and rhizomes near the soil surface. This structure highlights the high shoot density, which measures how many individual grass blades exist per square unit of area.
Grass Species Known for Natural Density
The perception of thick grass is linked to species that possess a lateral growth habit, allowing them to spread and fill in spaces effectively. Warm-season grasses like Zoysia and Bermuda grass are notable for their aggressive lateral growth through above-ground runners called stolons, or below-ground stems known as rhizomes. These structures allow the plant to colonize an area quickly, resulting in a dense, interwoven stand that resists weeds.
St. Augustine grass, another warm-season variety, is known for its coarse texture and wide blades, which create a visibly thick appearance, though its density comes primarily from its broad leaves. In cooler climates, Kentucky Bluegrass is the common choice for thick turf due to its extensive system of rhizomes that creates a high shoot density. Turf-type Tall Fescue is also utilized, as its individual blades are relatively wide, contributing to a thick look despite a clumping growth pattern.
Physical Characteristics of Thick Grass
The thickness of a lawn is determined by a combination of shoot density and leaf texture. Shoot density refers to the number of individual grass blades per square inch, and a high count creates a soft, plush feel underfoot, like a dense carpet. Fine-bladed grasses, such as certain fine fescues, rely on this high shoot density to achieve their thick appearance.
Conversely, coarse-textured grasses, like St. Augustine or some Tall Fescues, have individual blades that are noticeably broader. These broader blades cover more surface area, creating a thick appearance even if the total shoot count is slightly lower than a fine-bladed turf. The growth habit, whether spreading or bunch-type, also dictates the overall visual density of the turf.
Consequences of Overly Dense Growth
While a thick lawn is desirable, excessive density can lead to negative consequences. One common issue is the build-up of thatch, which is a dense layer of partially decomposed organic matter, including stems and roots, that accumulates between the vegetation and the soil surface. High density promotes thatch because the volume of organic matter production outpaces its natural decomposition rate.
When the thatch layer becomes too thick, typically exceeding a half-inch, it acts as a barrier, preventing water, air, and nutrients from reaching the root zone. This accumulation can also raise the grass plant crowns, making them more vulnerable to environmental stress and damage from mowing.
The second major consequence is soil compaction, which occurs when the soil particles are pressed together, reducing the pore space for air and water. Dense turf can contribute to compaction by restricting the health of the soil below, which then hinders deep root growth and nutrient uptake.