Saint Augustine grass can be quite good at outcompeting many weed types. However, once a Saint Augustine lawn begins to lose some of its health and vigour, then many weed types can invade the turf very quickly and abundantly. Let’s cover some of the best and most effective means of killing Saint Augustine lawn weeds as quickly possible after an outbreak has occurred. While tackling all weed types in proper order.
Fertilize The Lawn First
Before beginning weed treatments, we want to fertilize the lawn first. This will achieve 2 different desired results for us. First it will increase the success rate of the weed killers by a large degree, and second is that it promotes the health and vigour of the turf to help bring it back to full health faster, thus allowing the turf to naturally outcompete weeds on its own.
Fertilize the lawn 3 to 7 days before beginning weed treatments.
Kill The Easiest Majority Of Lawn Weeds First
The biggest family of weeds are called broadleaf weeds. The term "broadleaf weeds" refers to characteristics which many weed types have in common. Many different weeds can fall into this category such as Bindii, Clover, Catsear, Dandelion and many many others.
Because so many weed types fall into the category of broadleaf weeds, these are the weeds we will want to target first with a broadleaf weed killer designed for safe use on Saint Augustine grass.
Using a Saint Augustine broadleaf herbicide, the solution is diluted in water in a large spray bottle with a wand attachment for spraying. The weed spray is then applied to the Saint Augustine lawn as per manufacturers guidelines, being careful not to apply too much, nor too little, so be sure to measure the lawn before mixing the required herbicide.
Second Application Of Broadleaf Herbicide
Within 2 to 3 weeks we'll begin to see our weeds dying off. But we can't rest on our achievements just yet. A closer look at the turf will reveal some younger weeds emerging, and some weed types that were sprayed - are still not dying.
This is normal.
Some tougher broadleaf weeds can require 3 to 4 treatments to control.
We want to apply a second application of Saint Augustine safe herbicide 2 to 3 weeks after the first. This will give a double hit for those harder to kill weeds which improves the chances of killing them, plus it will kill off those younger weeds very quickly as well.
Killing Annual Bluegrass
If we have Annual Bluegrass in the St Augustine lawn, then once we've allowed our Saint Augustine lawn to rest and recover for at least a few weeks from the last weed treatment, it’s time to treat and kill the Annual Bluegrass in our turf.
Annual Bluegrass weed killer should be mixed in a watering can as per manufacturers recommendations, and applied to the lawn. The herbicide is then watered into the lawn where it interacts with the roots of Annual Bluegrass to kill the weed.
Annual Bluegrass is best treated pre-emergent just prior to winter or just as winter begins, and mid-winter at the latest, once past these months the plant will become too mature and too strong and will easily resist most treatment methods, and will have likely already seeded itself for more weeds next winter.
More Difficult Weeds In Lawns
Once we have the majority of weeds under control, its time to tackle some of the more difficult weed types which may require specialized weed sprays or other treatments. The good news is that if the majority of our lawn is now weed free, then the last remaining tougher weeds may only be few in number, and may possibly be pulled by hand.
Bring The Saint Augustine Lawn Back To Health
These weed treatments will effectively kill the majority of weeds in heavily infested Saint Augustine lawns. We just need to be careful to space out the treatments to allow the turf enough time to recover between these herbicide treatments being applied to it.
While undertaking these weed treatments, we should also be actively trying to bring the lawn back to full health, which simply involves following good lawn care practices.
Because a strong healthy Saint Augustine lawn will naturally fight off many weed types on its own.
We began by fertilization of the turf. Be sure to follow up this fertilization every 2-3 months afterwards using a good quality lawn fertilizer with trace elements. Or after longer periods if using a slow release lawn fertilizer product.
Mow the lawn regularly, as this promotes green leaf growth, and removes many seeds from many weed types before they have an opportunity to reinfect our lawns.
Check lawn watering, that the lawn is receiving enough water, as well as not too much water. Aiming to water the lawn more deeply and less often. An application of wetting agents will also help the lawn soil distribute water throughout its profile far more effectively too.
Finally, check and rectify any other factors which may be leading to poor lawn health. Reduce cars or other foot traffic to the turf if possible, remove excessive shade, and check and rectify water logging or other issues, and we'll soon bring our St Augustine lawn back to full health once again and naturally fighting off weeds all on its own.