Tall fescue (Festuca arundinacea) is a perennial cool-season grass whose identity depends entirely on context. It often serves as a desirable turfgrass in one setting while being an invasive nuisance in another. The determination rests on the specific variety present, the type of lawn it is growing in, and the desired aesthetic of the landscape.
Defining Tall Fescue: Turfgrass or Invasive Weed?
Tall fescue is used widely across North America for both low-maintenance turf and for livestock forage. Its positive attributes stem from an extensive, deep root system, providing superior resilience against environmental stresses. This deep rooting makes it one of the most drought-tolerant cool-season grasses, allowing it to remain green during summer heat.
When intentionally planted, modern cultivars known as “turf-type tall fescue” (TTTF) are prized for their durability and ability to thrive in the challenging transition zone. These improved cultivars have been selectively bred to have a finer leaf texture and a darker green color, creating a dense, uniform lawn. TTTF offers high tolerance for foot traffic and moderate shade.
The perception of tall fescue shifts dramatically when the common or “forage-type” varieties, such as Kentucky 31 (KY-31), appear in a lawn composed of fine-bladed grasses like Kentucky bluegrass or perennial ryegrass. These older varieties have much wider, coarser blades and a distinctly rough texture that stands out noticeably from the surrounding turf.
The primary reason tall fescue is considered a weed in this scenario is its bunch-type growth habit. As a bunchgrass, tall fescue spreads primarily by tillers, which are vertical shoots, rather than by horizontal runners. This growth pattern causes it to form isolated, dense clumps that expand outward over time, creating an uneven and unsightly texture across a manicured lawn. The coarse, clumpy patches are often the first to green up in the spring and the last to lose color in the fall, making them highly visible contaminants.
Key Characteristics for Visual Identification
Identifying tall fescue requires a close look at its physical structure, particularly when it appears as a coarse clump within a finer lawn. The most apparent characteristic is the width and texture of the leaf blade, which can be up to 12 millimeters wide in the older, weedy types, appearing significantly thicker than most desirable turfgrasses. The upper surface of the leaf blade is heavily ribbed, featuring prominent parallel veins that can be easily felt.
The stiff, tough blades often resist a clean cut during mowing. This resistance results in a tattered or jagged appearance at the tip of the blade, which quickly turns brown and gives the clump a distinct, ragged look. The underside of the leaf is smooth and often possesses a glossy texture.
To confirm the identification, examine the collar region, which is the junction where the leaf blade meets the sheath around the stem. Tall fescue has a rolled vernation, meaning the new leaf emerges rolled rather than folded. It typically exhibits a short, membranous ligule and short, blunt auricles—small, ear-like appendages that may partially clasp the stem.
Effective Strategies for Removal and Control
Tall fescue is a perennial grass, and its deep, extensive root system and bunch-type growth mean that selective herbicides designed to kill one type of grass without harming another are ineffective. Control strategies must therefore focus on eradication.
Physical Removal
For small, isolated clumps, the most reliable removal method is physical excavation of the entire plant. Using a shovel or a knife to dig out the clump ensures the complete removal of the crown and the deep roots, which is necessary to prevent regrowth. It is imperative to extract the entire root mass.
Chemical Removal
If the infestation is widespread, a non-selective herbicide, most commonly a product containing glyphosate, is necessary to kill the entire plant. This chemical application must be a careful spot-treatment, as the herbicide will kill any desirable grass it contacts. This non-selective approach is the only effective chemical solution, but it will leave behind bare patches of soil once the fescue dies, which usually takes about ten to fourteen days.
After the tall fescue has been successfully removed, the resulting bare soil must be promptly addressed to prevent new weed establishment. The area should be amended with topsoil if needed, and then reseeded or sodded with the desired turfgrass variety. To discourage re-establishment, maintain a dense, healthy lawn by mowing the surrounding turf at a higher height, typically around three inches or more, to shade the soil and favor the desired grass.