Bermudagrass vs St. Augustinegrass: Which Should You Plant?

St. Augustine can crowd out bermuda in shaded areas, but bermuda almost always wins in full sun. The two grasses partition by sun exposure: in dense shade where bermuda thins out, St. Augustine fills in via its aggressive stolons. In open sun, bermuda is the more aggressive spreader and will invade St. Augustine over time. If you want one or the other to dominate the whole lawn, you need to match the grass to the lighting condition; trying to convert one to the other while the underlying sun pattern stays the same does not work.

Neither is a low-maintenance grass; they are roughly tied but have different demands. Bermuda needs more mowing (every 3 to 5 days in summer vs every 7 to 10 for St. Augustine) and more fertilizer (4 to 5 lbs nitrogen per year vs 3 to 4 for St. Augustine). St. Augustine needs less mowing but more pest scouting; chinch bugs can wipe out an entire St. Augustine lawn in 2 to 3 weeks if untreated, and gray leaf spot disease is common in humid Gulf Coast summers. For a low-maintenance Southern lawn, centipede is the better choice than either of these.

St. Augustine survives most Texas winters in the southern half of the state (south of roughly Austin), but is at risk in central and north Texas where hard freezes are common. The 2021 February freeze killed wide swaths of St. Augustine across the entire state, including normally safe areas. If you live north of Austin or in the Panhandle, bermuda or zoysia is the safer pick. South Texas and the coast can rely on St. Augustine year over year.

Bermudagrass is significantly better for backyards with dogs. Bermuda recovers from worn paths and dig spots in 5 to 10 days through its rhizome-and-stolon network; St. Augustine takes 3 to 6 weeks to recover the same damage and the stolons can be torn out by determined diggers. Dog urine spots affect both grasses similarly, but the faster overall recovery makes bermuda the right choice for active dog households.

Overseeding St. Augustine with bermuda is not recommended. The two grasses thrive in opposite shade conditions, so a mixed lawn will end up with bermuda taking the sunny patches and St. Augustine dominating the shade. Worse, common bermuda seed is hard to eradicate once it establishes, so you cannot easily reverse the decision later. If you have a St. Augustine lawn that is thinning, the right move is plug or sod-patch with more St. Augustine, or replace the dead area completely with bermuda if the cause is too much sun for St. Augustine to handle.