St. Augustine Weed Control Guide
CRITICAL: 2,4-D herbicides DAMAGE St. Augustine. Most "Weed & Feed" products contain 2,4-D and will injure or kill your lawn. Atrazine is not a safe substitute either — Floratam, the most common St. Augustine cultivar, is not tolerant of atrazine (Texas A&M EHT-144), and a sod receipt rarely tells you which cultivar you have. SA-safe herbicides: Celsius WG (broadleaf + grassy, labeled for St. Augustine including Floratam), Dismiss (sedge control), and metsulfuron (broadleaf). Pre-emergent program: apply a prodiamine-based product before soil temps hit 55°F at 4-inch depth. For nutsedge: use Dismiss or Sedgehammer. Always read herbicide labels for St. Augustine-specific rates, which are often lower than bermuda rates.
Frequently Asked Questions
Can I use Weed & Feed on St. Augustine?
Most Weed & Feed products contain 2,4-D, which damages St. Augustine. Never use a product containing 2,4-D on St. Augustine. Read every label before applying.
What herbicides are safe for St. Augustine?
Celsius WG (post-emergent broadleaf) and Dismiss (sedge control) are safe for St. Augustine, applied per label. Atrazine is not — Floratam, the most common cultivar, is not tolerant of it (Texas A&M EHT-144). Always verify on the product label.
How do I control crabgrass in St. Augustine?
Use prodiamine as a pre-emergent in early spring, before soil reaches 55°F at 4-inch depth. Quinclorac is NOT safe for St. Augustine, and neither is atrazine — Floratam is not tolerant of it (Texas A&M EHT-144). For crabgrass that is already up, hand-pull or spot-treat and reseed; prevention is the real control.
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