Types Of Weeds In St Augustine Grass

Last Updated on April 1, 2023 by Mattias

One of the best qualities of st augustine (Stenotaphrum secundatum) is that this grass is highly resistant to invasive weeds. Thanks to its aggressive growth rate and competitive characteristics, weeds barely stand a chance against your st. augustine lawn.

However, you should know that even though the probability is extremely low, weed invasion is not entirely impossible. Some certain practices can trigger weeds and if your lawn isn’t strong enough then it won’t be able to outgrow weeds. 

If you are wondering about the intensity and nature of weeds then keep reading this article and learn all about the types of weeds in st augustine grass.

Types Of Weeds In St Augustine Grass

If your st augustine lawn is lacking primary care and its health is compromised then several types of weeds can get a chance to attack and overtake. The most common types of species that can attack your st augustine grass includes broadleaf weeds such as henbit, clover, chickweed, and dollar weed. Apart from that, grassy weeds such as bermuda grass, poa annua, dallisgrass, and crabgrass are just as likely to overtake your lawn and fight st augustine for essential nutrients. 

If you are not sure about the importance of knowing the types of weeds in st augustine grass then the answer is quite simple. identifying the weed leads you to understand what you’re working against. Once you know how the weed works, you can determine its intensity and see the level of damage it can cause.

This process helps you categorize weeds on an urgency level and gives you a headstart to control the weeds. Identifying types of weeds in st augustine grass also makes it easy to control it. You can target the weed’s weak spots and discourage its growth.

Furthermore, classifying them under appropriate categories helps you choose the right products and selective herbicides for weed control.

Types Of Broadleaf Weeds In St Augustine Grass

There are plenty of weeds that can attack your lawn and a huge portion of them are attracted to st augustine grass. Narrowing it down, some of the most common broadleaf weeds are listed below

Broadleaf, as the name suggests, are the type of weeds that have broad-sized leaves. They are thicker and their general appearance is easily distinguishable from your lawn’s grass.


  • Nature 

Chickweed (Stellaria media) is undoubtedly the most common weed that can infest your lawn. It is a wild plant and a winter weed that can produce up to 20,000 grass seeds in a single season. Since st augustine is a warm-season grass, it will be dormant during cold weather and its ability to fight weeds will be low.

Chickweed flowers will have little competition and they will grow aggressively until your entire lawn is covered. Identifying chickweed in your lawn is quite simple. Its flowers are 1⁄4 in size and they rarely grow more than 2 inches. It has five white petals and an equal number of sepals supporting it.

Fact: common chickweeds have shallow roots and they are not likely to grow back once you remove them.

  • Solution 

If you have spotted chickweed before it got out of hand, here are a few things you can do to prevent its invasion.

  1. Pull the roots out by using manual force
  2. Use appropriate herbicides
  3. Cultivation- can be done if plants haven’t grown too much


  • Nature 

Henbit (Lamium amplexicaule) is also a winter annual weed that is likely to attack your lawn in cooler months. It is a non-toxic species whose seed starts germinating in fall or spring (less likely to be early spring) regardless of the season, this weed doesn’t pop up until winter. Henbit is a tough weed that is disliked because of its aggressive growth and invading characteristics.

If you have a poorly maintained st. augustine lawn and your grass is thinning out then henbit is most likely to attack. It is also attracted to a moist soil surface and overwatered grass. You can identify it in your lawn by looking for a plant that is 10-25 cm tall. Its square-shaped stems are hairy, and its green-purple color is hard to ignore. Since it is a broadleaf weed, you should eliminate it at first sight.

  • Solution 

Here’s how you can prevent henbit from spreading 

  1. Control their growth when they are young
  2. Keep a thick and healthy lawn
  3. Do not plant grass under shady areas

White clover

  • Nature 

White clover, scientifically known as Trifolium repens L. is one of the most common perennial weeds that can attack house lawns. This weed is found nationwide and its aggressive growth rate makes it a threat to lawns and turfs.

One of the worst characteristics of white clover is that it doesn’t only overtake your grass but also attracts bees to your lawn. This increases maintenance costs and requires extra work. Clovers have deep roots which enable them to creep and enter gardening areas as well. The possibility of invasion increases when your st augustine lawn is under-fertilized and exposed to full sun.

White clover weeds are easily recognizable because of their trifoliate arrangement. Each leaf of this white flower is made up of 3 leaflets that are oval in shape and ¼ inches in diameter. You’ll notice that these weeds grow close to the ground and they have sparsely haired stems.

  • Solution 

The most effective solution to get rid of this fast-spreading weed is the application of herbicide. 

Dollar leave

Dollar leave (hydrocoele spp) is another type of common broadleaf weed that can attack your lawn and take it over. It is a perennial warm-season species that can offer tough competition to your active st. augustinegrass and fight it for dominance.

This weed is most likely to pop up in your lawn if your watering schedule isn’t appropriate. It is highly attracted to wet and moist areas so if your growing medium isn’t well-drained then be prepared for dollar leaves.

You can spot dollar leaves in your lawn by their appearance. This weed is distinguishable because of its bright green color and round-shaped leaves. Even though it is also referred to as “pennywort”, its primary name – dollar weed comes from its dollar-shaped leaves. This weed can float in water and its leaves are attached to long stalks.

  • solution

Dollar leaves can be prevented by the following methods

  1. Install a good drainage system 
  2. Fahrenheit herbicides
  3. Cut back on watering 
  4. Dig it out by hands 

Types Of Grassy Weeds In St Augustine Grass

Unlike broadleaf weeds which are easily identifiable because of their distinct appearance and broad size, grassy weeds are much more difficult to spot. Grass blades are likely to blend together so well that you won’t even notice that your st augustine lawn is being harassed. 

You can get rid of these weeds by pulling them out by roots and mulching afterward but the best way to get rid of any grassy weed is a selective herbicide

Bermuda grass

Bermuda is one of the fastest growing warm season grasses whose aggressive growth makes it both a desirable turf grass and an invasive weed. If this grass is your dominant lawn turf then you’d be able to enjoy the benefits of its dense growth and quick establishment. 

However, that isn’t the case when this grass is being used as a secondary/ alternative species. If your st augustine lawn is weak then even a little bit of planted bermuda can take over. 

This grass has dual methods of reproduction which means that it spreads both through its underground stems (rhizomes) and above-ground stems (stolons). Its creeping growth habit enables it to send shoots all over the surface and create various clones of the original plant. Not only that but its deep root system is hard to get rid of and it can easily outgrow st augustine grass. 

Since the two lawn grasses blend together so well, it is extremely hard to catch this problem

Poa annua

Poa annua, also known as annual bluegrass is a hybrid variety that is considered a low-growing turfgrass. Poa annua is considered a weed because it competes with every other species and its fast growth rate overtakes turf pretty quickly. Despite its shallow roots, this grass is tough and persistent. 

Its appearance isn’t desirable either and no one intentionally wants to have this grass on their lawns. It has hairless leaf blades that are yellow in color and they grow in short unsightly clumps. 

Poa annua will invade your st augustine lawn if you aren’t taking proper care and the grass is weak or damaged. It will also be drawn to the areas that are shady and overwatered. Apart from poa annua weeds, diseases such as mole crickets and chinch bugs are also attracted to these conditions. 


Dallisgrass is an invasive grass species that originates from Brazil. It is a common weed that spreads aggressively through its rhizomes and threatens your established lawn. Dallisgrass can invade various turfgrasses including Zoysia, bermuda, and st augustine. 

To make matters worse, dallisgrass is also a perennial species which means that its roots never fully die. This grass comes year after year to invade your st augustine lawn through the same root system.

If you’re not sure how to spot it in your lawn then look for a grayish-green colored grass that has a coarse texture and sparsely haired leaf blades. 

This grassy weed will invade your st augustine lawn if conditions are poor and the soil is continuously damp. Dallisgrass is attracted to wet and damp habitats so if your watering habits are not adequate then you may face this problem. 

How To Prevent Weed Invasion In St Augustine Grass

If you have noticed flowers with a similar appearance on your st augustine lawn then it’s time to take some necessary measures. If left unattended, these weeds can form a dense turf and carpet your entire lawn. They can even outgrow dormant st augustine grass and force it to die.

You can prevent this from happening by using adequate weed control products. It is a good idea to use herbicides as they will eliminate weeds effectively and show the best results. Pre-emergent herbicides such as isoxaben can be used to prevent the problem and post-emergent herbicides can be used to solve it.

Unless you are ready to replace the entire lawn, make sure to use selective herbicides, they will target your desired species and only kill them.

Non-selective herbicides, on the other hand, kill everything they make contact with and even a slight negligence on your part can damage st augustine grass severely. Read the instructions on the product label and make sure that it only kills specific weeds that you want to be eliminated. 

Furthermore, If you don’t prefer using chemical herbicides then you can manually pull the weeds out. This method is not likely to work with grassy weeds if their growth has spread out.

All things aside, the best way to solve weed problems in your lawn is by fixing the root cause. Most, if not all weeds primarily attack your lawn because of its poor maintenance and unhealthy growth.

If you keep your st augustine grass in check and take care of its essential needs then the grass will fight off weeds without your interjection

Tips for lawn maintenance 

  • Mow your lawn regularly to eliminate weed seeds before they fully germinate 
  • Water your lawn at an adequate amount and refrain from overwatering 
  • Install a good drainage system 
  • Feed fertilizers to your st augustine lawn in order to make it tough and weed resistant 
  • Always keep an eye out for lawn weeds
  • Encourage its growth by fulfilling growth requirements 

Types Of Weeds In St Augustine Grass Summary

St augustine is one of the most famous warm-season grasses that establishes carpeted turf. Its primary growth season remains from late spring to early summer but weeds can attack at any time. This grass is desirable and highly used in southern regions however, a weed-invaded lawn doesn’t look nearly as attractive. If you want to prevent this problem and solve weed invasion once and for all then it’s extremely important to know about the types of weeds in st. augustine grass lawns.

The key takeaway from this article is that there are two main types of weeds (broadleaf and grassy). However, several other variations and kinds fall under these categories. We discussed some of the most common types of broadleaf and grassy weeds that may attack your st. augustine grass lawn. We hope that understanding their nature and learning about their appearance will help you prevent and rescue your lawn.

Furthermore, St augustine grass is tough enough to compete with weeds so as long as you maintain a healthy lawn, the type of weeds will not be a problem for you.

Did you find this article helpful? Lawn weeds are never welcomed guests so if you want to save your friends’ lawns then share this information with them as well.

Leave a Comment