Mother Nature can be a clever mistress, indeed. She can be so clever that she can disguise a variety of different common weeds that look like desirable grasses.
An invasion of such a grassy weed is insidious. It doesn’t appear to be a serious problem for your lawn until it’s already become a serious problem.
These weeds hide in plain sight and can be easily overlooked if you don’t know what you’re looking for.
That’s what this article is all about. We are going to provide you with a list of weeds that look like grass. You’ll discover how to identify each grassy weed and learn some different control methods for each one.
So, before these common weeds that look like common lawn grasses become an issue, let’s dive in and take a look.
1. Annual Bluegrass (Poa annua)
What it Looks Like
Annual bluegrass (Poa annua) is one of the most commonly misidentified weed grasses. It is a close relative of the desirable cold-season Kentucky bluegrass.
As with all members of the Poa genus, annual bluegrass has canoe-shaped tips on its grass blades. Because they mimic the shape of other Poa species, the best way to identify these grassy weeds is to look for their brighter and lighter green color.
Annual bluegrass also has a long ligule, or membrane, that connects that leaf blade to the base of the stem.
Annual bluegrass is also a cold-season weed grass. They tend to congregate in shady areas with excess moisture. The heat and light from the sun will dry these grassy weeds out and leave bare patches in your yard.
Control Methods
Annual bluegrass can be treated with both pre-emergent and post-emergent herbicides. However, the best way to ensure that you don’t have it hiding on your lawn is to create a habitat not suitable for its growth.
If you have areas of your yard that are shaded, open them up by trimming back the trees or shrubs that provide the shade. For moist areas, ensure that the soil isn’t compacted and is properly draining. These two prevention methods should do your grass justice and keep annual bluegrass at bay.
2. Crabgrass (Digitaria sanguinalis and Digitaria ischaemum)
What it Looks Like
If you’ve not heard of crabgrass, then you’re not spending enough time outside. Because these grassy weeds are everywhere. Digitaria sanguinalis (also called large crabgrass) is predominantly found in the northern part of the country, and Digitaria ischaemum (also called smooth crabgrass) is the crabgrass species that dominates the southern part.
But crabgrass is crabgrass. And none of it’s good. This grassy weed makes its home on unhealthy yards. So if your lawn is under-watered, under-fed, and poorly drained, then you’re probably going to have a problem with crabgrass.
Crabgrass plants are annual weeds that will die off each year. That may sound like good news until you hear that each crabgrass plant is capable of producing more than 150,000 seeds that can germinate every spring.
Crabgrass grows in clumps on your lawn. While it does look similar to normal grasses, it has a much thicker growth habit and is altogether an unattractive eyesore on your lawn. If the seeds do germinate and grow unchecked, the blades can grow as long as 2 feet. Crabgrass is generally a lighter green than most desirable lawn grasses. Once its root system is established, it spreads quickly and aggressively across your lawn.
Control Methods
Just like annual bluegrass, you can get rid of crabgrass with one of many selective pre-emergent herbicides to prevent the seemingly countless seeds from germinating. If you’re too late for that, a selective post-emergent herbicide will also clear up the problem. However, your best bet if the seeds have already germinated is to recognize and pull the crabgrass plants before they’re old enough to go to seed.
The best defense, however, is a good offense. And a good offense, in this case, is ensuring that your lawn is healthy and thick. Take care to ensure proper fertlization, watering, and drainage on your property. This will keep your desirable grass too thick and healthy for crabgrass to invade.
3. Yellow Nutsedge (Cyperus esculentus)
What it Looks Like
Yellow nutsedge is a perennial weed that can attack your lawn from above the soil and below. Seeds can be spread through the air from above the soil level and through its rhizomes, or tubers, below the soil’s surface.
The fact that it’s a perennial weed that will reappear each growing season only complicates matters further.
When yellow nutsedge is young, it will have light green colored grass blades. As it ages, the grass blades will become a deeper green. This change in color can make it hard to identify amongst your desirable lawn grass.
Yellow nutsedge is best identified by looking at its root system. On its roots, there will be nut-like tubers growing from them. These tubers give the grassy weed its name.
Control Methods
The best plan of action for controlling yellow nutsedge is to keep your lawn lush and healthy. A healthy lawn will do its own work and prevent nutsedge from having a place to invade. So be sure to do the upkeep using proper maintenance practices, and you should be fine.
Since yellow nutsedge is a perennial grassy weed, once it shows up on your lawn, the best way of getting rid of it is a heavy dose of post-emergent herbicide.
Pulling the weeds may cause you more problems because leaving the smallest piece of these plants in the soil guarantees that they will regenerate and make a repeat appearance on your lawn. If you decide to go this route, ensure that you remove every single fiber of the yellow nutsedge from the ground.
4. Green Foxtail (Setaria viridis)
What it Looks Like
Green foxtail earns its name because, once it is fully grown, a piece of the plant resembles the tail of a fox. This piece that resembles a fox tail is a seedhead that can produce hundreds of problematic seeds that can spread through your lawn and garden.
Green foxtail is an annual grassy weed that will require the germination and growth of brand new plants every year.
Identification can be tough before the plant grows its seedhead. Its blades are a normal green color and don’t have a remarkably different shape than most desirable lawn grasses. Its growth habit is normal as well. So this one can be tough to spot.
Control Methods
Since it’s an annual weed, you can control green foxtail by pulling it out. Preferably, you’ll have it removed before it goes to seed. But, as you already know, this can be a difficult task because it looks so similar to your grass before that point.
If you find that green foxtail has already gone to seed, you can pull the plant from the soil and use a pre-emergent herbicide to keep the green foxtail’s seeds from germinating in the spring.
If the invasion is too great to pull all of the grassy weed out, you can use a selective post-emergent herbicide to kill it off. You’ll still need to treat the ground with a pre-emergent herbicide at some point before the seeds begin to germinate when the weather warms up.
5. Creeping Bentgrass (Agrostis stolonifera)
What it Looks Like
Creeping bentgrass is often planted intentionally. But this intentional planting is usually relegated to the fairways and putting greens on manicured golf courses and not on your yard.
Creeping bentgrass can spread aggressively in your grass and garden through its stolons.
Creeping bentgrass will appear in light green patches in your grass. Its blades are generally finer and thinner than most desirable grasses. If you allow creeping bentgrass to grow taller than 1 inch, it will take on a puffed-up or swollen appearance.
Cool-season creeping bentgrass is averse to excessive heat and will turn brown quickly at even slight elevations in temperature.
Control Methods
Because creeping bentgrass propagates and spreads through its stolons beneath the soil’s surface, one plan of attack is to use selective herbicides on this hardy perennial plant. An herbicide containing glyphosate is your best bet. However, this may only work if you catch these lawn weeds very early in their life cycle.
Creeping bentgrass is often more widespread than it may seem. This is due to it spreading underground through its stolons. On average, if you have a patch of creeping bentgrass with a diameter of 1 foot, you actually have a mix of the grassy weed and your desirable grass that extends three times that diameter. This makes spot-treating creeping bentgrass very difficult.
Unfortunately, the nature of these weeds makes them very difficult to completely eradicate once they are established. So, you’re either going to have to start over by removing all the grass entirely and reseeding or start promoting the growth of creeping bentgrass on your property.
To promote creeping bentgrass, you’ll need to shift your focus from soil fertility and nutrition to pest control. Because pests are one of this weed’s primary afflictions.
6. Common Couch (Elymus repens)
What it Looks Like
Common couch is a hardy perennial grassy weed that also goes by couchgrass and quackgrass. These weeds are equally at home in shade and sun.
Common couch spreads through both its underground rhizomes and its airborne seeds. Once it is established, its root system becomes exceedingly difficult to remove completely. So, it’s best if you can catch it early.
Common couch has a coarse texture and will appear on your lawn in patches. It’s blue-green color can be hard to distinguish amongst some desirable grasses.
The blades of these grassy weeds look similar to fingers. Their growth habit wraps these finger-like blades around the stem at the base of the plant.
Control Methods
If it is allowed to grow unchecked, common couch will take over your lawn in no time. It makes its home on areas that are thinned or bare. So, an unhealthy lawn makes the perfect victim for these weeds.
Whenever you come across common couch in your lawn or garden, you can pull it up by hand. But, if you do, you need to ensure that every piece of the plant is removed from the soil. Otherwise, you’re destined for another visit as soon as it can regenerate.
Chemical control will require both pre-emergent and post-emergent herbicides because it spreads underground through its rhizomes. So you have to ensure that the hardy root system is dead to prevent its propagation.
The best defense against common couch (and this feels like it’s becoming a theme) is a healthy, vibrant, and thick lawn. It will outgrow the weeds, and they won’t have any space to invade.
7. Smooth Bromegrass (Bromus inermis)
What it Looks Like
Just like couchgrass, smooth bromegrass is a perennial weed that can spread through either rhizomes or seeds. It also has a robust root system that will be difficult to get rid of once it becomes established in your lawn.
Smooth bromegrass can grow to heights of over 7 feet. Its blades, or leaves, grow to between 8 inches and 2 feet long. The blades hang down in a drooping manner. The blades are covered on both the upper and lower surfaces by fine hairs.
This weed’s color ranges from a light to a normal shade of green. The upper portions of the blades can be lighter in color because of their length if growing conditions are poor.
Control Methods
Fortunately, you can control smooth bromegrass by keeping it cut short with your mower or weedeater. Keeping it short will allow your desirable grass to crowd it out eventually, and you won’t have to resort to any chemical herbicides.
However, if the weeds have spread out and established themselves, you’ll need to use some strong pre-emergent and post-emergent herbicides to quell the invasion. Use an herbicide with glyphosate for the best results.
8. Carpetgrass (Axonopus compresus and Axonopus affinis)
What it Looks Like
These weeds share the same genus and have similar physical traits, so they’re lumped together under one name. Carpetgrass is a perennial weed that can grow to heights of a foot or more. It will appear on your lawn in very thick mats that are shaded a normal green color.
In the summer, they will produce seed heads that look very similar to those of crabgrass. The seed heads will be taller than the rest of the plant.
Carpetgrass prefers acidic soil with high moisture content. You will probably find them congregating and growing in shady areas that do not receive adequate sunlight. This allows the moisture levels to build up in the soil.
Control Methods
One good thing about carpetgrass is that you can control it through natural methods. All you have to do is raise the pH level of the soil. You can do this by adding lime or salt mixed with a gallon of water. One of these two should do the trick.
Of course, if you catch it early enough, you can pull it from the earth. However, since it is a perennial weed, you’ll need to ensure that you remove every last piece of it from the ground.
9. Tall Fescue (Festuca arundinacea)
What it Looks Like
This may be confusing because tall fescue is used as a desirable grass on some lawns. However, much like creeping bentgrass, it can show up without an invitation and take over your lawn. Ironically, the very things that make this such a desirable grass are also the things that make it a worthy opponent in your yard.
Tall fescue has distinct blades or leaves. The leaves of tall fescue are thick and broad. They have pronounced veins running the length of the blades, and this gives them a coarse texture. The blades are colored bright green, and the lower surface is a lighter green than the upper surface.
Control Methods
When it comes to tall fescue, I have some good news and some bad news. The bad news is that it is an extremely hardy plant that is very drought resistant. Once it shows up in your grass, it can be challenging to remove it completely.
It spreads through underground rhizomes, so its initial damage assessment may be underestimated. It can be spread further than it appears at first.
The good news is that you can beat tall fescue with natural means. Solarization is the best technique to use. Cover the weeds up with black plastic, newspaper, a tarp, or cardboard and let the heat, combined with a lack of sunlight and oxygen, suffocate the invasion out of your yard.
10. Johnsongrass (Sorghum halepense)
What it Looks Like
Johnsongrass is a perennial weed that is relatively easy to identify and control, which is a different story than the rest of the perennial weeds in this article.
When johnsongrass is in its early stages of life, it resembles the seedlings of the corn plant we all know and love. Left to grow unchecked, it can reach heights of over 7 feet.
Its seed head will start out green and then transition to a purplish maroon color.
As johnsongrass matures on your lawn, you’ll be able to pick it out because its leaves will become up to an inch thick and have a distinct white vein running down the middle of each blade.
Control Methods
There’s an easy way to control it and a hard, labor-intensive way to control it. The easy way is to cover the entire plant with highly concentrated vinegar. Be careful not to spray anything you don’t want to kill because vinegar is non-selective.
The hard, labor-intensive control method is used for larger johnsongrass invasions. It spreads through its rhizomes under the soil along with its seeds. So, to kill the johnsongrass, you’ll need to expose those rhizomes to the elements by using a tiller to cultivate the earth containing them. Do this later in the fall and expose the rhizomes to the cold winter temperatures, and they won’t be making a second appearance in the spring.
