I remember the day I laid my brand new sod and the amazing feeling I felt admiring my perfectly green and lush yard. I wanted to keep my lawn looking just like that forever. But if you’ve got a lawn, you know that keeping it weed-free is a full-time job, no matter if it’s new sod or an already established lawn.
So, if you’re sitting there admiring your St Augustine lawn, wondering what the best method is to prevent weeds, you’ll first have to learn what weeds you are likely to encounter and how to deal with each type. Let’s take a look at the 8 most common weeds in St Augustine grass.
Which Are the Most Common Weeds in St Augustine Grass? (The Short Answer)
Several types of weeds are common in St Augustine grass and fall into two main categories: broadleaf weeds and grassy weeds. Here are the 8 most common weeds in St Augustine grass.
4 common broadleaf weed varieties:
- Chickweed
- Dollarweed
- Henbit
- Clover
4 common grassy weed varieties:
- Annual Bluegrass
- Crabgrass
- Dallisgrass
- Bermudagrass
A Closer Look At Common Weeds that Affect St Augustine Grass
When healthy, St Augustine grass is excellent for snuffing out weeds. But unfortunately, no grass is immune to weeds, and the best way to keep weeds off your St Augustine lawn is to know what you’re dealing with and the specific methods to get rid of them. So, let’s go over 8 types of weeds in St Augustine grass and how to control them.
4 Common Broadleaf Weeds in St Augustine Grass
Broadleaf weeds are easy to spot in the grass because their rounded leaves are very different from your St Augustine’s long, thin shoots. But each weed is different, and it’s important to know what you’re dealing with. So, here are the 4 most common broadleaf weeds you’ll find in your St Augustine lawn.
Chickweed – Stellaria media
Chickweed is a very common broadleaf weed found all over the states. You’ll easily spot it by its small star-shaped white flowers and oval leaves that grow opposite each other along a light-green hairy stem.
One of the ways I control Chickweed in my lawn is by spraying a pre-emergent herbicide in the fall months when the Chickweed is germinating. If it happens to pop up in my lawn during the growing season, then I mow it down and use a clipping bag to prevent the seeds from spreading and becoming an even bigger headache next season.
Dollarweed – Hydrocotyle
Dollarweed thrives in the same conditions as St Augustine grass, which is why you’ll likely find its glossy leaves spotted around your yard. You’ll know it’s a Dollarweed by its round leaves that resemble a silver dollar.
This pesky weed is immune to the mower since 90% of the plant actually lives underground. So my best advice is to arm yourself with a good post-emergent broadleaf targeted herbicide with Metsulfuron Methyl and a lot of patience since this could be a long battle if the Dollarweed becomes well-established.
Henbit – Lamium amplexicaule
Another common weed across the United States is Henbit. This annual weed germinates in the fall and sprouts in the springtime. Henbit will stand out in your St Augustine grass with its purple flowers and heart-shaped leaves.
If you can see the flowers, then make sure to use a clipping bag when mowing to avoid spreading seeds all over your yard. And believe me, there will be a lot of seeds since each plant can produce over 2,000 of them. Also, you can get a broadleaf post-emergent herbicide with Atrazine which is safe on your St Augustine grass and helps get rid of Henbit.
Clover – Trifolium
If you have any bare patches in your St Augustine grass, then Clover is likely to make a home there. You’ll quickly notice this 3-leaved weed with white flowers between the spring and fall.
As soon as I spot a Clover cluster, I pull them out and dig out any remaining roots, which is pretty easy to do since it has a shallow root system. Because Clover grows in bare areas, I try to fill in any empty spots in my yard with new sod or plugs.
4 Common Grassy Weeds in St Augustine Grass
Most grassy weeds look a lot like St Augustine grass, so knowing a few key characteristics will help you know which grassy weed you’re dealing with. Unfortunately, most herbicides that tackle grassy weeds will also hurt your St. Augustine lawn. So, let’s go over the characteristics of 4 common grassy weeds in St Augustine grass and how to get rid of them.
Annual Bluegrass – Poa annua
This low-growing turf grass is one of the most common grassy weeds that can make a home in your St. Augustine grass. It has a brighter shade of green than St Augustine, and you’ll see its white feathery seed heads pop up early in the growing season.
Your St. Augustine grass will develop bare spots in the summer once the Annual Bluegrass dies off. This grassy weed likes shady, moist areas, so make sure to keep your soil well-drained to prevent Annual Bluegrass from growing in your St. Augustine lawn.
Whenever I’ve had Annual Bluegrass in my lawn, I let my grass grow 3-4 inches which helps to block the sunlight from reaching the roots.
Crabgrass – Digitaria
It’s pretty easy to spot Crabgrass growing in your St. Augustine grass by its coarse and yellow-green leaves. You can also tell it apart because it grows low to the ground since the shoots grow outwards, much like the shape of a crab.
Crabgrass grows in clumps in bare spots, so I like to avoid this stubborn grassy weed by keeping my lawn thick and healthy and plugging bare areas. It’s not only good for keeping the weeds away, but it makes my yard look better too.
I always avoid using herbicides on my lawn to control Crabgrass because it will likely hurt my lawn too. So, if some Crabgrass does make its way into my lawn, I like to hand-pull the clusters as soon as I spot them.
Dallisgrass – Paspalum dilatatum
If you see scraggly, tall weeds popping up in your St. Augustine lawn, then you are likely dealing with Dallisgrass. This common weed in St Augustine grass has tall shoots and caterpillar-like seed heads.
For me, the best way I’ve found to tackle this grassy weed is by removing the clusters with a shovel. Because it spreads by seed, I always make sure to use a clipping bag when I mow over any Dallisgrass in my lawn that has gone to seed. If you don’t catch the seeds, you’ll really be in trouble.
Bermudagrass – Cynodon dactylon
If you live in any of the southern states, then you’ve probably dealt with Bermuda grass growing on your St Augustine lawn. These two types of grass are high competitors and thrive in similar climates. You can spot Bermuda grass in your lawn by its thin, hair-like, and soft blades.
My best method for controlling Bermudagrass growing in St Augustine lawn is to grow my lawn a bit longer than usual. Bermuda grass needs a lot of sunlight and can easily shade itself out if left to grow long, so by growing the St Augustine grass longer, you can block the sunlight and crowd out the unwanted grass.
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