Killing weeds in Saint Augustine grass has always been a major concern for homeowners. While quite safe for many lawn types, the active ingredient in many lawn weed killers was often Dicamba, which would damage or even kill the grass when it was used on a Saint Augustine lawn.
These days we have many more choices which are readily available to effectively kill weeds in Saint Augustine grass lawns. We simply need to be aware that we need to purchase a product which is clearly labelled as safe for use on Saint Augustine grass.
If the product is not clearly labelled as safe for St Augustine grass, then we can do a simple check on the label for the active ingredient in the herbicide:
- MCPA and Bromoxynil based herbicides are generally safe for use on Saint Augustine grass.
- Dicamba based herbicides are never safe for use on Saint Augustine grass.
So our preferred weed killer for use on St Augustine grass will have the safe active ingredients of MCPA and Bromoxynil to effectively kill many weed types safely in Saint Augustine grass, and we want to ensure these products are manufactured by a highly respected herbicide company which manufactures products for home use.
Applying Saint Augustine Grass Weed Killer
A Saint Augustine safe weed killer is a concentrated herbicide which will need to be diluted in a handy sprayer with water. Dilution and application ratios are printed clearly on the product packaging.
Warning - do not apply more herbicide or mix the herbicide any stronger than manufacturers recommendations, applying too much herbicide can still damage any lawn type, not just Saint Augustine grass.
Repeat Applications of Lawn Herbicide
Some weeds can be quite robust, and therefore difficult to eradicate in a single spray, other weed types will have masses of seeds already in the soil, and therefore will continue to produce more weeds, even though the last lot were killed.
If weeds re-emerge after spraying, or some weeds still remain alive, repeat the weed spraying again in another 2 weeks or as specified on the product label of the weed killer you are using.
Do Not Spray Weeds After Lawn Mowing
As with all weed killers, never spray any herbicide on a lawn within a week of its last lawn mowing. The open wounds created from mowing will quickly absorb any herbicide, and will damage or perhaps even kill any lawn type, not just Saint Augustine grass.
It's also a great idea to never mow the lawn until one week after mowing, this allows ample time for the weeds to take up the herbicide before it is removed with lawn mowing.
Professional Saint Augustine Grass Weed Spraying
Some weed types can be extremely difficult to eradicate in a St Augustine grass lawn. If you're experiencing ongoing weed control problems in your Saint Augustine lawn, then it may be wise to hire a professional and licensed weed spraying contractor.
A professional weed spraying contractor will have expert knowledge and access to chemicals to treat weeds that the homeowner cannot access themselves. In these cases, it is highly recommended that the homeowner hire a professional spraying contractor, and one who guarantees their work!