Weeds in a lawn are already a headache. If they look like grass, they’re double the problems as eliminating them becomes even harder. Such weeds like crabgrass, nutsedge, common couch, and others present a problem that needs careful assessment on your end to solve.
Invasive weeds that look like grass include crabgrass, nutsedge, quackgrass, clumping tall fescue, green foxtail, and annual bluegrass. Some of the grassy weeds are tough to control and may require the application of a selective pre-emergent and post-emergent herbicide to get rid of.
Tall grass weeds in a lawn with medium to tall grass can easily pass for part of the lawn until they’re assessed closely. Herbicides that kill the grass family would kill the weeds and your grass. This calls for other elimination methods discussed below.
Why are some grasses considered weeds in lawns?
A lawn looks great if it has one type of grass or several types but arranged in a certain way. Unwanted grasses would mess up the look of your lawn since they introduce a different look.
For example, they’ll have a different leaf structure, introduce some flowers and some pests and diseases. They also compete the primary grass for water and nutrients thus making it grow poorly.
10 Invasive weeds that look like grass
Some invasive weeds which can easily pass for grass include the following:
1. Crabgrass
Crabgrass, also called finger grass, is an invasive weed looking like grass. If you find a weed that looks like Bermuda grass, that’s likely crabgrass. It can sprout in any part of your lawn and will spread quickly once it sprouts in one part of the lawn. Its growth starts in small patches which spread out in concentric circles.
It has a course texture compared to most types of grass and is an annual plant. These traits are advantageous to you as you can tell it apart from the rest of the lawn, and you can be sure it’ll die after the season comes to an end.
The main problems caused by crabgrass are that it spreads quite fast and its damage is permanent. In fact, it crowds out and smothers other plants growing around it if left to spread.
How to get rid of crabgrass
The best method of getting rid of crabgrass is to prevent its germination. For this one, you should use a pre-emergent herbicide on your lawn. Most pre-emergent herbicides are combined with fertilizer.
If, however, the crabgrass has already germinated, you should just pull it out using a crabgrass remover individually or use a direct contact herbicide. These methods will require some hard work on your part but they’re the best options you have against this weed.
Read also: Best Crabgrass Killers Safe for Lawns
2. Nutsedge
There are different types of nutsedge but all look like grass and quite a headache to get rid of once they get into your lawn. Before maturing and blooming, nutsedge looks a lot like tall grass.
The main difference it has with crabgrass is that it’s perennial in nature. As such, it’ll go on for two seasons if not controlled. It’s spread both by underground tubers and rhizomes, and airborne seeds. For this reason, it can easily move from a neighboring farm to yours in a short while.
How to get rid of nutsedge
When dealing with nutsedge, never pull them out as you’ll only be spreading them further. You’ll only pull out the stems but leave the roots and tubers which will only grow stronger the next round.
A good approach to dealing with them before they start spreading is to grow a thick lawn that chokes out grassy weeds. This way, they’ll find no space to sprout and spread out. From the start, make sure your lawn is healthy and growing thick.
If they’re already in your lawn, apply a selective herbicide such as Sedgehammer Plus Herbicide directly to the base of the plant to kill the root system and the plant as a whole. It’s a headache doing so on each root but that’s the best way to do it.
Pro tip: You’re not supposed to pull nutsedge because it will come back quite easily unless you do so early in its life cycle. Otherwise, the tubers break off and you make more independent plants, thus increasing the population of nutsedge grassy weeds in your lawn.
3. Green Foxtail
The green foxtail gets its name from the stalks of its heads which look like foxtails pointed upwards. Green foxtails are common in meadows and prairies and can grow to between 10 to 100 centimeters in height.
Their seeds, contained in the foxtails, spread by wind and can be carried for great distances to cause havoc in lawns and pastures. Each foxtail has hundreds of tiny seeds which prefer warm soil between 15 and 35 degrees Celsius (59 to 95 degrees Fahrenheit). They can, however, germinate in any season with favorable conditions.
How to control green foxtails
The best method of dealing with this weed is having a thick lawn to crowd them out. Other than that, you may employ herbicides which are applied directly to the plant to prevent damage to the surrounding grasses.
4. Slender Rush
Slender rush is often called ‘path rush’ or ‘poverty rush’ and it grows in clumps much like how crabgrass grows. It’s a bright green weed that looks like grass and spreads both by tubers in the ground and seeds on the surface. These aspects make it quite tough to deal with since the normal methods of herbicides and uprooting can still leave it fertile and ready to germinate.
How to control slender rush
Slender rush can be put under control with both herbicides and manual methods such as uprooting them whenever they appear. Always aim to uproot them from the roots to prevent their re-emergence.
Another method is mowing the lawn frequently to prevent their maturing to the seeding stage.
5. Wild Garlic and Onion
As their names suggest, they’re very similar in appearance to garlic and onion plants. They even smell exactly like them and can be used in your dish in the place of actual garlic and onions.
One way to know they’re in your lawn is that they give off a smell of freshly-cooked pasta sauce right after you’ve finished mowing your lawn. Physically, they look like tall grass. They usually have a faster growth than your lawn grass and will thus appear in clumps above the rest of the lawn.
How to control wild garlic and onion
One way to control them is to transplant them to your garden or pot for use like onions and garlic in your dish. Yes, they’re very much edible and delicious. Their growth is in early spring and late fall (they’re dormant in the summer) makes it easy to pick them out and deal with them.
If you hold them in a large enough clump when the ground is moist, you can uproot them with the tubers which is also effective in dealing with them.
Herbicides can also be used to deal with them. When choosing your herbicides, make sure they act on this particular weed since most don’t.
6. Quackgrass (Common Couch)
Common couch is also called quackgrass or simply couch grass and it looks very much like grass. Couch grass spreads by both seeds and underground rhizomes which makes it very tough to deal with especially once it’s established itself.
How to control couch grass
Like most other weeds on this list, couch grass is also controlled through crowding it out with the grass in the lawn. Basically, taking good care of your lawn makes it robust enough to keep the weeds at bay.
If the weeds establish themselves before your lawn is thick and robust enough to fend them off, you’ll need a herbicide applied directly to the weeds.
7. Smooth Bromegrass
Smooth bromegrass is a perennial grass-like weed that’s quite difficult to kill off given its hardiness. Besides being perennial in nature and highly adaptable even to cold environments, it also propagates itself through rhizomes in the soil and a very robust root system. In a thin lawn, it’ll easily take over.
Beyond being a nuisance, smooth bromegrass is great at providing ground cover owing to its robust growth and tight root system. It also makes great hay if you needed it for this purpose.
How to control smooth bromegrass
Given its growth behavior, the best way to beat smooth bromegrass is to crowd it out with a thick lawn. You should attempt this after mowing down the lawn for the best results.
When this fails, go for herbicides applied directly to the plant.
8. Tall Fescue
Tall fescue is a tough weed that grows in thick clumps and is spread by rhizomes in the soil. It’s resistant to drought and most conditions that can kill your lawn. In fact, its leaves look almost like succulent stems. As such, when it invades a lawn, it’ll quickly crowd out the grass and kill it off.
How to control tall fescue
The best way to deal with tall fescue is to solarize it. Solarizing entails covering sections of your lawn with an impermeable material such as nylon paper for long periods of time. This section is deprived of sunlight, air and water while its temperatures become unbearable to the plants. Eventually, they die off.
Herbicides can work although the amounts needed to kill the weeds would be so large that you’ll just harm the environment in the process. The cost of the herbicides won’t be economical as well.
Trying to uproot the weeds won’t work since you’ll just likely leave the rhizomes in the soil where the grasses will grow from.
9. Annual Bluegrass
Annual bluegrass is popularly called ‘Poa’ and is an invasive weed that has a thick growth in cool and moist environments. It prefers growing in areas with enough water and some shade if possible.
The grass often dies in the summer or when the temperatures rise and there isn’t enough rain. This is a good and bad thing. It’s good since the weeds will die off by themselves, and bad because it dies off and leaves ugly bare patches in your lawn.
How to control annual bluegrass
It’s relatively easy to control this weed since you can simply crowd it out with a thick lawn of your own.
Given that it requires cool and moist conditions, you can also kill it simply by letting the lawn dry up a little. When it starts dying off, you can then dig it out, plant good grass then water the area.
Where these methods don’t work, you can always resort to herbicides to be applied directly to the weeds.
10. Alexandergrass
Alexandergrass, also called tropical signalgrass or creeping signalgrass, is a perennial weed that looks like St. Augustinegrass. It has quite a robust growth and would easily choke out the latest of the lawn if not taken care of quickly enough.
How to control Alexandergrass
At the moment, there is no herbicides that can kill Alexandergrass. As such, the only solution is using baking soda to burn it off before digging it up and replanting that section of the lawn.
These weeds can be easily mistaken for grass and the only way to tell them apart is that they’re not similar to the grass in your lawn. In some cases, however, they may pass for your lawn grass until they’ve messed up your lawn. For this reason, always observe your grass to understand its growth so that you can identify any weeds early on.
Most of the weeds in this list are grasses, so why did you speak of them as though they are not? Being a weed does not mean that a plant isn’t a grass.
Hello Neha, weed is anything unwanted in the area of interest or that competes with any cultivated plant. As such, the discussed 10 are considered weeds when they sprout in unwanted areas.