Bermuda Grass Invading St. Augustine: No Selective Herbicide—Outcompete It

There is no herbicide that kills Bermuda without harming St. Augustine—both are warm-season grasses with similar physiology. The solution is cultural: make St. Augustine so vigorous that it crowds out Bermuda.

Strategy

1. Water more. St. Augustine needs more water than Bermuda. Deep, frequent irrigation favors St. Augustine.
2. Mow high (3.5–4 inches). St. Augustine tolerates taller mowing; Bermuda weakens.
3. Organic program. Sugar, compost, alfalfa meal build soil health, giving St. Augustine the edge.
4. Plug gaps. Plant St. Augustine plugs in thin areas to accelerate coverage.

Expect 3–4 Years

In North Texas, plugging St. Augustine into Bermuda took 3–4 years to fully dominate. Patience and consistent culture win.