The presence of unwanted grass clumps, often caused by older, pasture-type varieties of tall fescue (Festuca arundinacea), disrupts the uniform appearance of a lawn. This perennial grass is characterized by its ability to withstand drought and heat, allowing it to survive harsh conditions that cause surrounding lawn species to struggle. Tall fescue forms dense clumps rather than spreading uniformly, leading to a patchy texture and color variation. Removing this persistent grass requires a strategic approach, starting with accurate identification and moving through targeted removal methods to long-term prevention.
Identifying the Unwanted Fescue
Accurate identification is the first step before beginning any removal effort. Undesirable tall fescue is easily recognized by its distinct physical characteristics compared to finer lawn grasses like Kentucky bluegrass or perennial ryegrass. Look for leaf blades that are notably wider and thicker, often measuring up to one-half inch across. These coarse blades grow upright and have a stiff texture, making them stand out from the surrounding turf.
The most telling sign is its bunch-type growth habit, forming isolated, dark green clumps that do not spread via rhizomes or stolons. This clumping pattern creates a visible textural difference. Tall fescue also exhibits a darker, blue-green color and tends to green up earlier in the spring. During summer drought, these patches frequently remain green while desirable turf goes dormant, making the clumps particularly noticeable.
Non-Chemical Removal Techniques
For homeowners who prefer to avoid the use of herbicides, several physical and environmental methods can effectively eliminate fescue clumps.
Manual Extraction
The simplest method for small, isolated patches is manual extraction, which involves physically removing the entire plant and its deep root system. Use a sharp spade or trowel to cut a circle around the clump, loosening the soil with a garden fork before carefully lifting the mass of roots and soil. It is important to dig deeply, often several inches, to ensure the dense crown and all major roots are completely removed to prevent regrowth.
Solarization
For larger, more established areas of fescue, solarization provides an effective solution that sterilizes the soil using solar energy. This method involves covering the affected area with a sheet of clear, UV-resistant plastic, typically 2 to 6 millimeters thick, during the hottest months of the year. First, the soil should be moistened. Then, the plastic is laid flat and secured tightly around all edges, often by burying them in a trench, to trap heat. The sun heats the soil beneath the plastic to temperatures exceeding 140°F, which is lethal to the grass and any seeds in the top few inches of the soil profile. Solarization requires a duration of approximately four to six weeks in peak summer heat to be successful, though cooler climates may need up to ten weeks. The intense heat not only kills the existing fescue but also eliminates many pathogens and weed seeds, preparing the area for replanting.
Smothering
Another non-chemical option is smothering, which uses layers of organic material to block sunlight and suppress the grass. This technique involves laying down a thick layer of overlapping cardboard directly over the fescue, making sure to remove any tape or labels. A layer of organic mulch, such as wood chips or compost, is then spread over the cardboard to a depth of four to six inches. The cardboard and mulch combination starves the grass of light, causing it to die back and decompose while simultaneously improving the underlying soil structure. Smothering is a slower process, generally requiring six to ten months to fully kill the turf, but it is an excellent choice for converting a lawn area into a garden bed or a large patch that is not needed immediately.
Chemical Control Strategies
Non-Selective Herbicides
When manual removal is impractical due to the extent of the infestation, chemical control becomes the most efficient option, though it requires careful application. The primary chemical approach relies on non-selective herbicides, particularly those containing glyphosate, which is a systemic compound absorbed by the leaves and translocated throughout the plant to the root system. Because glyphosate kills all vegetation it contacts, it is primarily used for spot treatment of individual fescue clumps or for complete renovation of heavily infested sections of the lawn.
To ensure minimal damage to the surrounding desirable turf, the herbicide must be applied precisely to the fescue leaves. This is often done using a sponge applicator or a sprayer shielded by a container like a cut-off plastic bottle. The optimal timing for application is in the late summer or early fall when the fescue is actively growing and moving resources down to its roots in preparation for winter dormancy. This downward movement efficiently carries the systemic herbicide to the deepest parts of the plant, maximizing the kill rate.
Selective Options
A significant challenge in fescue control is the limited availability of truly selective herbicides for use in cool-season lawns like Kentucky bluegrass. Herbicides that target fescue without harming desirable cool-season species are rare for the average homeowner. One notable exception is the active ingredient mesotrione, sold under the trade name Tenacity, which can suppress or partially control coarse fescue in established turf. This product works by inhibiting photosynthesis, causing the targeted grass to turn a distinct white color before it dies back. Full eradication with mesotrione often requires multiple applications and is most effective when the fescue is young and actively growing. For most home lawns, it is generally safer and more straightforward to use a non-selective spot treatment, accepting that the resulting dead patch will require subsequent repair. Always consult the product label for specific application rates, safety precautions, and the necessary waiting period before replanting.
Lawn Restoration and Future Prevention
After the unwanted tall fescue has been removed, focus must shift to restoring bare areas and preventing recurrence. Where clumps were dug out or killed, soil preparation is necessary before new seed can be introduced. Rake the area thoroughly to remove all dead debris, then loosen the soil surface to ensure good seed-to-soil contact. Amending the soil with a thin layer of compost or a starter fertilizer high in phosphorus provides emerging seedlings with necessary nutrients.
The best time for reseeding cool-season grasses is early fall, when warm soil temperatures encourage germination and cooler air temperatures reduce stress on the young grass. Keep the area consistently moist with frequent, light watering until the new grass establishes itself, typically two to three weeks.
Long-term prevention relies on cultural practices that favor desirable turf. Maintain a higher mowing height, ideally between three and four inches, as taller grass suppresses weed seed germination. Water established lawns deeply and infrequently to encourage deep, drought-resistant root systems. A dense, healthy, and properly maintained lawn is the strongest defense against re-establishment.