A lawn with a mix of different grass species often develops a patchy, inconsistent appearance due to variations in color, texture, and growth rate. Achieving a single, cohesive turf requires a strategic approach, ranging from simple maintenance adjustments to a complete overhaul. The goal is to minimize visual differences or physically eliminate unwanted species to cultivate a uniform stand of grass.
Identifying the Different Grass Types
Successfully repairing a mixed lawn depends on accurately identifying the different grass types present, which determines the most effective management or removal technique. Turfgrasses are broadly categorized as either cool-season, thriving in temperatures between 60°F and 75°F, or warm-season, preferring temperatures of 75°F to 90°F.
Distinguishing features include growth habit and blade texture. Some undesirable grasses, such as tall fescue, grow in distinct, coarse clumps (bunch-type). Others, like Bermuda grass or Kentucky bluegrass, spread through underground rhizomes or above-ground stolons (creeping-type). Observing grass color and blade width also helps; for example, fine fescues have delicate, dark green blades, while St. Augustine grass has a broad, coarse texture. Knowing when a patch greens up or goes dormant helps determine its seasonality and guides control methods.
Cultural Practices for Uniform Appearance
Before resorting to removal, cultural practices can be adjusted to favor the desired grass species and visually minimize differences. Adjusting the mowing height is an effective strategy for hiding coarse, clumping species.
Raising the mowing height allows the desired grass to develop a deeper root system and a denser canopy, suppressing the growth of unwanted varieties. For most cool-season lawns, maintaining a height between three and four inches is recommended, as this shades the soil and stresses shallow-rooted weeds. Never remove more than one-third of the grass blade in a single mowing session to minimize stress on the turf.
Watering practices can also stress unwanted, shallow-rooted grasses. Instead of light, frequent watering, use deep and infrequent irrigation. Watering about an inch deep once or twice a week encourages the desired grass to grow deeper roots, making it more resilient to drought than competing species. Timing the fertilization schedule to benefit the dominant grass type helps it outcompete others by providing a growth advantage.
Targeted Removal and Spot Seeding
When cultural practices are insufficient, targeted removal of invasive patches becomes necessary. For small, isolated clumps of bunch-type grasses, such as tall fescue, physical removal is the most direct method. The entire clump, including its root structure, must be dug out to prevent regrowth, leaving a small bare spot.
For larger, invasive patches, a non-selective herbicide containing glyphosate can be used for chemical removal. Because this chemical kills any plant it contacts, meticulous application is required to avoid harming desirable turf. A common technique involves using a foam paintbrush or a spray shield to apply the herbicide directly to the leaves, minimizing the risk of drift or overspray. After the patch has completely died (typically one to two weeks), the dead material should be raked out.
The resulting bare patch must then be prepared for reseeding with the desired grass cultivar. The soil should be loosened, and high-quality grass seed matching the surrounding lawn should be spread over the area. To ensure good seed-to-soil contact, the area can be lightly rolled or covered with a thin layer of topsoil or peat moss. Specific selective herbicides, such as those containing mesotrione, can be safely applied at seeding to provide pre-emergent control against weeds without harming the germinating turf.
Complete Lawn Renovation
If the lawn is heavily contaminated with multiple grass types or invasive species covering more than 50% of the area, a complete renovation is necessary to achieve uniformity. This process involves intentionally killing the entire existing lawn to create a clean slate for new turf.
The first step is the blanket application of a non-selective herbicide across the entire lawn area. The grass must be actively growing for the herbicide to be absorbed and translocated throughout the plant, ensuring a complete kill. A waiting period, typically one to two weeks, is required after application to allow all plant material to die completely before proceeding with soil work.
Next, the dead turf is removed or aggressively dethatched, and the soil is prepared through aeration to relieve compaction and improve drainage. Once the soil is ready, the area is seeded with a single, high-quality cultivar of the desired grass type, or sod is laid down for an immediate result. Reseeding is less expensive than sodding but requires consistent, light watering to keep the soil surface damp until seedlings are established. The best time for renovating cool-season lawns is in the late summer or early fall, when temperatures favor germination and establishment.