Weed Killer for St. Augustine Lawns

A white bag of Lawn Synergy Starter 15-20-10 professional lawn fertilizer with green geometric accents and branding.

RECOMMENED NOW

Emerald 10-0-20

Tall Fescue, Kentucky Bluegrass, Zoysia, St. Augustine, and Centipede Lawns.

RECOMMENED NOW

Almighty 20-0-10

Bermuda Lawns & Lawns needing more growth.

Seeding or Sod

Starter Fertilizer

The Key to Faster Germination & Stronger Roots

Organics Option

BioBoost

Build up organics within the soil while also feeding the lawn.

Measure Your Lawn

Order the correct amout of product based on the sq ft of your lawn.

Spreader Settings

Common spreader settings for various lawn products.

Explore Now

Shop by Category

Lawn Fertilizer

Feed your lawn for season-long results.

Grass Seed

Clean weed-free seed for a ultra-dark green lawn.

Weed Control

Clean up pesky weeds that don't belong in your lawn.

Fungicide

Prevent and cure disease in your lawn and ornamentals.

Insecticide

Don't let insects destroy your lawn. Treat ticks mosquitos, and more.

Shop By Lawn Type

Tall Fescue

Bermuda

Zoysia

St. Augustine

Centipede

Northern Lawns

Not sure what your lawn needs?

Join our Lawn of the Year Program and take the guesswork out of lawn care. We’ll deliver the right products at the right time, so your lawn gets exactly what it needs all season long.

Learn More

How It Works

1

Choose Your Lawn

Tell us your lawn type and goals.

2

Get Your Program

We recommend the right products and timing.

3

Apply With Confidence

Simple steps for a thicker, greener lawn.

1

Choose Your Lawn

Tell us your lawn type and goals.

2

Get Your Program

We recommend the right products and timing.

3

Apply With Confidence

Simple steps for a thicker, greener lawn.

Weed Killer for St. Augustine Lawns — St. Augustine grass is a popular warm-season turf, but it is also more sensitive to herbicides than many other grass types. Using the wrong weed killer can cause serious damage. This collection features selective herbicides that work safely on St. Augustine lawns, helping you control weeds without harming your turf when applied as directed.

From common broadleaf weeds like clover and spurge to nutsedge and certain grassy weeds, these professional-grade products are widely used on St. Augustine lawns. This collection is designed to help you choose products that balance strong weed control with turf safety.

When you purchase from Lawn Synergy, you’re backed by expert support. If you’re unsure which product is right for your lawn—or need help with mixing rates, timing, or application techniques—our team is here to help you get professional results with confidence.

Weeds This Collection Helps Control in St. Augustine

Broadleaf weeds: clover, spurge, chickweed, plantain, dandelion
Sedges: yellow nutsedge and other sedge species
Grassy weeds: crabgrass and certain annual grassy weeds
Tough weeds: deep-rooted and difficult-to-control warm-season weeds

Quick Guide: Pick the Right Weed Killer

Weed Problem	Great Product Options	Why It Works
General Broadleaf Weed Control	Celsius WG, Celsius Xtra, Atrazine	Excellent broadleaf control with strong St. Augustine turf safety
Tough or Mixed Weed Pressure	Celsius Xtra, Negate, Atrazine	Broader-spectrum control while remaining safe on St. Augustine when applied correctly
Nutsedge	SedgeHammer, Certainty, Vexis(granular)	Targets sedges specifically without damaging St. Augustine turf
Crabgrass & Grassy Weeds	Quintessential	Controls certain grassy weeds with careful timing and proper application
Specialty Weed Situations	Celsius Xtra, Vexis, Quintessential	Used in specific situations—expert guidance strongly recommended

Current Best Sellers

Headway G Fungicide

$78.95

Prevent and cure disease

Emerald 10-0-20 Lawn Fertilizer

$39.99

Low nitrogen stress blend

Almighty 20-0-10 Lawn Fertilizer

$39.99

High nitrogen for growth

Bifen 7.9F Insecticide

$29.95

Treats insects and mosquitos

Pro-Grade Products

Fast Shipping

DIY Friendly

Expert Support

Got Questions?

Frequently Asked.

Are these weed killers safe for St. Augustine grass?

Yes, when applied according to label directions. St. Augustine is more sensitive than other turf types, so product choice, rate, and timing are critical.

What is the best weed killer for St. Augustine lawns?

Celsius WG is widely considered one of the safest and most effective options for St. Augustine lawns.

What kills nutsedge in St. Augustine grass?

SedgeHammer, Celsius Xtra, and Certainty are commonly used for nutsedge control in St. Augustine lawns.

Can I control crabgrass in St. Augustine?

Yes, but timing matters. Products like Quintessential can help when applied correctly and under the right conditions.

When should I spray weed killer on St. Augustine lawns?

Spray when weeds are actively growing and St. Augustine is healthy and not under heat or drought stress.