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How Do I Get Rid of Weeds Without Killing St. Augustine Grass?

Weed control is a challenging part of lawn maintenance, particularly for St. Augustine grass, which shares the same basic needs—water, sunlight and soil contact—as weeds, making them an inevitable issue.

Furthermore, St. Augustine grass’s sensitivity to many herbicides complicates the matter. To safely eliminate weeds without harming this type of grass, products containing Atrazine, such as Hi-Yield Atrazine, are the best weed killers for St. Augustine grass.

Hi-Yield Atrazine Weed Killer

Hi-Yield Atrazine Weed Killer is an atrazine-based herbicide designed to control weeds like henbit, dollar weed, chickweed, clover, sandspur and others listed on the product label in St. Augustine and centipede grass. Available in a single quart bottle or single quart ready-to-spray bottle.

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St. Augustine grass, particularly varieties like Palmetto® and CitraBlue®, grows thickly, forming a dense canopy that naturally suppresses weeds by competing for space. Despite this advantage, weeds can still infiltrate St. Augustine lawns yearly.

Identifying the types of weeds present can provide insights into soil conditions and help develop targeted treatment strategies.

Continue reading to explore common weeds in St. Augustine grass, non-chemical controls, preventative measures and treatment options.

Weed Killer for St. Augustine Grass Lawns

Cultural Methods of Weed Control in St. Augustine Grass Lawns


Maintaining a healthy lawn is essential for effective weed control. Key practices include proper mowing, fertilizing and irrigating. Mow to a height of 2–4 inches to hinder weed seeding and spread, and ensure that grass clippings are collected to prevent redistributing any weed seeds. 

Mowing yourself also avoids cross-contamination from mower blades used on other lawns.

Regular fertilization increases lawn density, making it less hospitable to weeds. We recommend the Lawnifi® Fertilizer Program.

For minimal weed presence, hand-pulling is effective; however, this method becomes impractical with larger weed infestations.

Pre-Emergent Weed Control in St. Augustine Grass Lawns

Pre-emergent and post-emergent herbicides serve different purposes. Pre-emergents prevent weeds from emerging by applying them to the soil before weeds appear, which is especially useful for managing seasonal crabgrass in St. Augustine grass.

Apply these in early spring as temperatures approach 55 degrees Fahrenheit and again in fall when soil temperatures drop below 70 degrees. Post-emergents, on the other hand, treat visible weeds.

Using pre-emergents can save time, money and effort in weed removal. Hi-Yield Atrazine Weed Killer serves as both an effective pre- and post-emergent.

Post-Emergent Weed Control in St. Augustine Grass Lawns

Post-emergent weed control in St. Augustine grass requires careful herbicide selection due to its sensitivity to certain chemicals found in common herbicides like 2,4-D, dicamba, MCPP and MSMA, which can damage this type of grass.

To treat weeds, choose a post-emergent herbicide with Atrazine, which safely controls weeds without harming St. Augustine grass.

Ensure you read and follow the product labels for safe application.

How Do I Get Rid of Weeds Without Killing St. Augustine Grass? – Answered

To safely eliminate weeds without harming St. Augustine grass, use a post-emergent herbicide that contains Atrazine, such as Hi-Yield Atrazine Weed Killer, which is effective and safe for this type of grass.

Also, maintain a healthy lawn through regular mowing, fertilizing and irrigating to suppress weed growth naturally.

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