The sudden appearance of coarse, wide-bladed grass in an otherwise uniform turf is a common frustration for lawn owners. This unwanted growth breaks the texture and color consistency of a fine lawn, often appearing lighter or darker green than the surrounding desirable grass. These invaders are typically grasses that thrive under different conditions than your established turf. Their presence often serves as an indicator that the underlying lawn is experiencing stress, such as poor soil health or improper watering habits. Identifying the specific wide-bladed grass is the first step toward effective resolution, as different species require distinct methods for control and prevention.
Identifying the Most Common Offenders
The majority of wide-bladed grasses that invade lawns fall into three main categories, each requiring careful observation for accurate identification. The most frequently encountered is Crabgrass, a warm-season annual that appears in late spring or early summer after soil temperatures consistently reach 55 to 60 degrees Fahrenheit. This grass is characterized by a yellowish-green color and a prostrate growth habit. It spreads low to the ground and radiates outward from a central point, allowing it to easily avoid standard mower blades.
Tall Fescue is a cool-season perennial that becomes a weed when it appears as thick, isolated clumps in a lawn of finer grasses like Kentucky bluegrass. Its blades are noticeably coarser and wider, sometimes up to a half-inch across, possessing deep ribs on the upper surface that give it a rough texture. It maintains a dark green color, especially during drought, due to its exceptionally deep root system. This allows it to thrive when the surrounding turf struggles.
The third common invader is Quackgrass, another cool-season perennial identified by its distinctive blue-green color and upright growth habit. Unlike tall fescue, quackgrass is aggressive because it spreads extensively through underground stems called rhizomes. This makes it difficult to pull up completely. A distinguishing feature is the presence of a clasping auricle, a pair of finger-like projections that wrap around the stem where the leaf blade begins.
Prevention Through Proper Lawn Maintenance
Cultivating a dense, healthy lawn is the most effective way to prevent wide-bladed grasses from establishing themselves. Mowing height is a simple yet powerful tool. Raising the mower deck to its highest setting, typically between 3 and 4 inches for cool-season grasses, is highly recommended. This increased height allows the desirable turf to grow taller, shading the soil and preventing the sunlight needed for weed seeds, especially crabgrass, to germinate.
Watering practices also play a significant role in determining which grasses flourish in your yard. Shallow, frequent watering encourages a shallow root system in your turf, which is easily outcompeted by weeds. Instead, adopt a deep, infrequent watering schedule, aiming to supply one to one and a half inches of water per week. This practice encourages the turf’s roots to grow deeper, increasing its resilience and ability to dominate the soil profile.
Supporting soil health further discourages weed invasion by promoting vigorous turf growth. Compacted soil creates an environment that favors many weeds over fine turfgrasses. An annual aeration treatment, which removes small plugs of soil, can relieve this compaction and allow air, water, and nutrients to penetrate the root zone. A well-nourished, dense lawn naturally chokes out invading species by competing for space and resources.
Targeted Removal and Treatment
Once a wide-bladed grass is identified, removal methods must be tailored to its life cycle. For annual weeds like crabgrass, the primary defense is the precise application of pre-emergent herbicides in early spring, before the soil temperature allows seeds to germinate. If crabgrass has already appeared, a post-emergent herbicide with an active ingredient such as quinclorac can be applied. This selectively kills the established plant without harming the surrounding desirable turf.
Perennial wide-bladed grasses, including tall fescue and quackgrass, present a greater challenge because they cannot be selectively killed with standard lawn herbicides. The most reliable method for removing isolated clumps is spot-treating the specific plant with a non-selective herbicide, such as one containing glyphosate. This targeted application must be done carefully to avoid drift onto the surrounding desirable grass. The treated area must then be reseeded or patched after the weed has died completely.
Physical Removal
Physical removal by digging out the entire plant remains a viable option for small infestations. This includes removing the deep root system of tall fescue or the extensive rhizomes of quackgrass. However, any remaining root fragment of a perennial can lead to regrowth.