Identifying and Controlling the Four Meanest Grass Weeds

Not all grasses belong in your lawn. Four aggressive grassy weeds can destroy aesthetics, outcompete desirable turf, and resist standard control methods. Knowing them is the first step to reclaiming your lawn.

The Four Worst Offenders

1. Quackgrass (Elymus repens)

Perennial, reaches 5 feet. Extensive rhizome system—each fragment regenerates. Destroys lawn uniformity. Requires persistent removal or systemic herbicide.

2. Bentgrass (Agrostis stolonifera)

Used on golf greens, but invasive in lawns. Rapid stoloniferous spread forms dense mats that crowd out turfgrass. Difficult to eradicate once established.

3. Crabgrass (Digitaria spp.)

Annual, but prolific seeder. Germinates when soil hits 55°F. Grows fast, low, spreading. Frequent mowing needed if not controlled. Pre-emergent herbicide in early spring is best defense.

4. Foxtail (Setaria spp.)

Coarse texture, distinctive seed heads. Often confused with crabgrass. Extremely resilient—mowing, pulling, even partial herbicide treatment often fails. Deep roots regenerate aggressively.

Control Strategies

• Identification first: Treatment varies by species.
• Cultural practices: Dense, healthy turf (proper mowing, fertilizing, watering) naturally suppresses invasion.
• Pre-emergents: Timed for each species' germination window.
• Post-emergents: Selective herbicides for specific grassy weeds in turf.
• Persistence: Perennials (quackgrass, bentgrass) require multi-season effort.

Grass weeds originate from diverse regions—their growth cycles and vulnerabilities differ. Match your control strategy to the specific invader for effective, lasting results.