Bermuda grass (Cynodon dactylon) and crabgrass (Digitaria spp.) are often confused by homeowners managing warm-season lawns. Both are aggressive, warm-season grasses that thrive in hot weather and quickly colonize damaged turf areas. Understanding their distinct botanical identity is crucial, as their different life cycles require entirely separate control strategies.
The Fundamental Difference in Identity
Bermuda grass is a perennial turf grass, meaning individual plants return year after year. It enters a dormant, brown state only during the cold winter months. It is often intentionally planted for its resilience, ability to withstand heavy foot traffic, and tendency to form a dense turf layer. This grass spreads aggressively through above-ground stolons and below-ground rhizomes, establishing an extensive root system.
Crabgrass, conversely, is an annual weed. Its entire life cycle completes within a single growing season. It germinates in the spring, grows throughout the summer, produces thousands of seeds, and dies completely with the first hard frost of fall. The following year’s growth relies entirely on the germination of seeds left in the soil, which is a key difference from the established perennial root system of Bermuda grass.
Visual Cues for Proper Identification
Distinguishing between the two requires examining their growth patterns and leaf structure. Bermuda grass forms a dense, interwoven mat, spreading horizontally across the ground via its wiry, visible stolons. These tough runners connect patches across the lawn.
Crabgrass is a clump-forming annual that grows outward from a single central point, creating a sprawling patch that resembles a crab’s legs. Its leaves are noticeably coarser and wider than those of Bermuda grass. Bermuda grass blades are finer and narrower, resulting in a softer texture and a deep, vibrant green color. Crabgrass typically displays a lighter, yellowish-green hue.
Effective Management and Control Strategies
The difference in life cycle dictates the management approach for each grass. Crabgrass control focuses on preventing the germination of its annual seeds using pre-emergent herbicides. These chemicals must be applied in early spring, before soil temperatures reach 55 degrees Fahrenheit, to create a barrier that kills the seedling as it attempts to sprout. Once crabgrass has visibly emerged, post-emergent herbicides like quinclorac are necessary, but prevention is more effective.
Controlling Bermuda grass, especially when it acts as a weed in a cool-season lawn, is more difficult because pre-emergent products are ineffective against its established perennial root system. Elimination requires targeting the plant after emergence using selective post-emergent herbicides. These must be repeatedly applied to exhaust the energy stored in the extensive rhizomes and stolons. Non-selective herbicides, like glyphosate, can also be used for spot treatment, but this kills all vegetation it touches, requiring lawn renovation in the treated area.