Invasive Grass Types
A very tiny plant that attracts everyone with its beauty and offers calm and quiet to one’s mind, simply with its green expanse and sometimes tiny, colorful flowers is grasses!
Grasses occur everywhere (except on the south pole). A lot of them are not native to places where they occur. When it comes to North America, it’s believed that around 11% of the grasses are non-native.
They’ve been introduced here by traders and travelers. Most of these non-native grasses are considered to be invasive and a threat to other native grass species. To protect the native North American plants from the danger of extinction, conservation methods and management policies are required.
Published: October 21, 2022.
What are Invasive Grasses?
In the United States of America, too invasive grasses are a big concern for homeowners, especially if they resemble their regular lawn grass. Not all invasive grasses are non-native.
Some are native too but have the potential to outcompete other native grasses in communities where they often would be only minor components or absent from the plant community. Loss of native grasses negatively affects forage and watershed functions and can cause land degeneration and erosion.
The invasive grasses are introduced species that, in some regions, are able to create dense stands and negatively alter the native plant communities.
While these species replace major proportions of native plant communities, they may even modify vegetation structure, the fire regime, soil erosion rates, hydrology, and forage production. These changes, in turn, can have considerable effects on livestock production as well as wildlife populations.
Also, some species that are considered invasive in some areas are considered beneficial in other areas and are recommended for planting. Examples of these are smooth brome (Bromus inermis) and Kentucky bluegrass (Poa pratensis).
Invasive grasses are simply weeds that have a competitive advantage over the rest of the plants in one’s lawn. In other words, they grow faster, taller, and thicker than the rest of the grasses in their lawn, which can soon cause them to crowd out and choke off the growth of other grasses.
While some invasive grasses may not be a big problem and can, in fact, add some variety to one’s lawn, others can lead to extensive harm. For example, quackgrass is an invasive grass that has been known to grow through concrete.
Invasive weeds can crowd out one’s desirable grasses, causing bald patches on their lawn and allowing them to spread further.
Poa annua or annual bluegrass, is a small, tufted grass that occurs commonly in lawns. It has a light green to blue-green color and grows into a dense mat. Since it can germinate quickly, it can be problematic, which means it can outcompete one’s desirable grasses for space, nutrients, and water.
It also forms a lot of seeds, which can soon cause a large infestation if left unrestrained. This grass normally dies during the hotter months or when there is no rain. In a way, this is good because the weeds will die as well.
However, it’s bad too because the bald spots will appear as it dies out.
Getting Rid of Annual Bluegrass
- The most effective solution to eliminate the annual bluegrass problem is to crowd it out with a dense lawn of one’s own desirable lawn grass.
- One can also kill it by letting their lawn dry out so they can try not to water it as often as they have been
- When one’s lawn starts drying out, one can simply dig it out with a shovel
- If one finds bald patches after digging out, they can just sow some new grass seed
Also known as tropical signalgrass or creeping signalgrass, Alexandergrass is a perennial weed and has flat, hairless leaves. This weed is native to tropical and subtropical regions but can be seen even in temperate regions. It can grow in a wide range of habitats, including lawns, agricultural fields, gardens, and pastures.
This species of plant has a very powerful growth rate and if not managed properly, it will soon overrun the lawn. It’s also very drought-tolerant, which means it can survive periods of dry weather when other grasses would struggle.
Getting Rid of Alexandergrass
- No herbicides are available that can be effective at killing alexandergrass. Hence one’s best option is to use baking soda
- Once one applies the baking soda, they’ll need to dig it up with a shovel
- Alexandergrass can be easily mistaken for normal grass. Hence one needs to keep an eye on their lawn to avoid messing up
Also called finger grass, crabgrass is an annual invasive grass that resembles a lot to Bermuda grass. It can grow in several places, but one will usually find it growing on lawns and can spread at a very high rate. It typically begins sprouting in small areas of a lawn but will soon branch out in circular areas over a period of time.
Crabgrass’s structure is rougher and coarser than most grasses. This may help one distinguish it from the rest of their lawn. This weed is a problem since it can rob one’s other grasses of vital nutrients, water, and sun. this can create bald patches and, in general, an unhealthy lawn.
Crabgrass is an invasive grass that can quickly spread and lead to permanent damage to other plants if left unrestricted.
Getting Rid of Crabgrass
- One should use a pre-emergent herbicide to stop it from sprouting
- And/Or they can use a crabgrass mower to pull out individual crabgrasses
- Or they can use a direct contact herbicide if the above solutions are not effective
For more about this topic, feel free to check our How to Get Rid of Crabgrass Without Chemicals article.
Setaria viridis, or green foxtail, is an annual grass that germinates in the spring. It’s a very quick-growing weed that can spread fast and takes over spaces of lawns, gardens, meadows, prairies, and pastures. The plant has long green leaves that have a fox tail-like look, from which it gets its name.
This weed is usually confused with other grasses but still can be distinguished by its seed head, which is made up of several small spikelets. This weed can grow to be quite tall, sometimes attaining a height of even 2.5 feet or even more.
This weed forms a large number of seeds, which are dispersed by the wind. This means that it can rapidly spread to other spaces and become a problem.
Getting Rid of Green Foxtail
- Homeowners should grow a dense lawn from the beginning. In that scenario, the lawn will begin to crowd the patches of green foxtail and starve it of vital nutrients
- They can apply a selective herbicide straight to the unwanted grass to kill it off
Cyperus rotundus or nutsedge is a perennial invasive grass that can occur in several parts of the world. It’s a fast-growing weed that spreads rapidly and can easily take over lawns and gardens.
The main difference between nutsedge and crabgrass is that nutsedge is perennial, meaning it’ll last for two growing seasons if not eliminated.
This disruptive grass propagates through subterranean rhizomes/tubers as well as seeds carried by the wind. Due to this, it can soon spread to lawns from nearby farms.
Getting Rid of Nutsedge
- Homeowners should never try to pull it out in the early stages of its growth cycle. Or the tubers will break, spreading the roots or causing them to grow back stronger.
- They can grow a thick, luscious lawn from the beginning, thus preventing any chance of nutsedge weeds being able to spread. The dense lawn grass will crowd out the invasive species and will leave no space for germination
- Another solution to nutsedge is to use a selective herbicide
Elymus repens or quackgrass, is a very common type of invasive grass that occurs throughout North America. It’s a perennial grass that spreads through its seeds as well as rhizomes (creeping roots). This makes it very tough to get rid of once it’s established in one’s garden.
The weed has been named after its distinctive seed heads, which look like the tail feathers of a duck. Its leaves too are quite unique, being much wider than most other types of grass.
Getting Rid of Quackgrass
- The homeowner should grow a dense lawn to crowd and slowly starve the invasive weed
- They should apply a selective herbicide
Bromus inermis, or smooth bromegrass, is a perennial grass native to Asia and Europe and has been introduced to North America. It’s usually used as a forage crop or turfgrass but can become an invasive problem in some regions.
This perennial weed thrives in difficult environments (including cold climates). It spreads via rhizomes in the ground and develops a strong root system.
This introduced grass can soon overtake a thin lawn. It can alter the soil bacterial community by suppressing dominant bacterial species, letting rare bacteria increase in relative abundance.
Smooth bromegrass is harmful too as it encourages excessive growth and destroys surrounding vegetation. It has a fast growth rate and a robust root system that make it a perfect ground cover. It can even be used as hay.
Getting Rid of Smooth Bromegrass
- Homeowners should grow a thick lawn from the beginning to prevent smooth bromegrass from growing in the first place
- They should apply a selective herbicide
Juncus tenuis, or slender rush, is a kind of invasive grass native to Europe and has been introduced to North America. It often occurs in wet areas like ditches, marshes, and swamps.
It’s a fast-growing grass that can rapidly spread and take over an area. It propagates via ground tubers and seeds, which are dispersed by the wind. The weed forms thick mats which can crowd out other plants.
Getting Rid of Slender Rush
- When slender rush emerges, homeowners should uproot it by hand and remove it with herbicides. But they should do this from the roots to prevent regrowth.
- Alternatively, they can cut their grass on a regular basis to prevent the plant from developing beyond the seedling stage.
Festuca arundinacea, or tall fescue, is a grass that’s native to Asia and Europe but is now established in North America. It’s usually used as erosion control, turfgrass, and forage crop.
This is a pesky weed that thrives as dense clumps and spreads through rhizomes underground. It’s resistant to severe weather conditions, which makes it difficult to kill. Actually, its leaves look similar to succulent stems.
Hence when this weed infests a lawn, the lawn grass cannot compete and dies as a result.
Getting Rid of Tall Fescue
- The most effective solution to remove tall fescue is to solarize it, for which the homeowner should cover parts of their lawn with fabric such as nylon paper for prolonged periods of time.
Bromus tectorum, or cheatgrass, is a more prevalent type of annual brome grass. It’s also known as downy brome.
It has a tremendous potential to alter the ecosystems it invades, and it can totally replace native plantations and can change the fire regime.
Areas that once experienced fire once every 30-150 years may experience fires once every 3-5 years once cheatgrass is established in it. It’s also bad for wildlife like pygmy rabbits, mule deer, and sage grouse that depend on intact sagebrush steppe for survival.
Getting Rid of Cheatgrass
Homeowners should pull small areas by hand in the spring. Having shallow roots, cheatgrass is easy to root out before it sprouts and spreads its seeds.
- While traveling in areas known for cheatgrass, homeowners should brush off shoes, tools, vehicles, and other surfaces before returning home. Cheatgrass occurs often in prairies, wildlands, roadsides, and areas that have recently undergone fire damage.
- Homeowners should keep their yard moist by watering it more often because cheatgrass prefers dry conditions, and a moist environment is a deterrent.
- Cheatgrass is extremely inflammable, hence homeowners should not burn it after pulling it out. To prevent it from mixing up with other organic matter and germinating, they should throw it out.
- If manual pulling is not possible, homeowners should use equipment like mowers and tillers to remove it. After mowing, they should bag the clippings to prevent the seeds from spreading. But since this won’t destroy the root systems or remove seeds that have already entered the ground, they should apply a chemical method.
- If the cheatgrass has developed seedheads, homeowners should apply a product containing glyphosate or imazapic that will kill it. But they will likely need more than one application. Using vinegar is not recommended because a very strong industrial concentration of it will be needed, which will harm them, their pets, and other plants.
The history of Poa pratensis or Kentucky bluegrass (also known as KBG) in the US is quite complicated.
Although it’s commonly grown in pasturelands, particularly in the northcentral and northeastern regions of the country, as an important persistent perennial cool-season forage species, it’s listed as an invasive weed in Wisconsin and the Great Plains.
It was originally discovered in Northern Asia and Europe and was introduced in the US as a pasture grass in states like Kentucky, from where it got its name. It’s a popular lawn grass in residential and commercial landscapes due to its beauty and dark green color.
Although it’s a cool-season grass, it’s versatile enough to survive and flourish in warmer conditions. It's not uncommon to find KBG in lawns in the West and Southwest parts of the US if they receive a lot of sun and the soil is extraordinarily moist.
Getting Rid of Kentucky Bluegrass
- Several homeowners don’t see Kentucky bluegrass as a weed and prefer it to be their main desirable lawn grass because of its dark blue-green color and dense, beautiful appearance.
- It also looks much similar to annual bluegrass. Thus, if a homeowner wants to get rid of it, they should first learn to identify the difference between the two. They should carefully observe how the leaf blade connects to the sheath. If there is a white ligule there, it’s annual bluegrass. If there is no ligule, it’s Kentucky bluegrass.
- The best way to get rid of KBG is to prevent it from entering the lawn in the first place, since once it’s established and starts growing, it’s hard to eradicate it. So, applying a pre-emergent such as Barricade to make sure KBG doesn’t emerge in the spring and is killed completely.
- If it’s already established, one should apply post-emergent products like Certainly Herbicide.
Pennisetum ciliare or buffelgrass, is a perennial, invasive grass that is immune and highly resistant to drought and can choke out native grasses.
This tall grass burns quickly when dry if ignited, which makes it particularly hazardous during wildfire season.
Getting Rid of Buffelgrass
- If the buffelgrass plant is green, the gardener can use herbicides to kill the plant since the herbicide works only on actively growing plants.
- If less than 50% of the plant is green, the best method to remove it is manual removal.
- With any removal method, the gardener should perform a follow-up treatment for the next 3-5 growing seasons to remove the seed that is still in the soil.
- For chemical treatment, products containing glyphosate are very effective and easily available.
- For manual removal, mowing alone is not effective. On the contrary, it stimulates new growth.
- The homeowner should use a digging tool to loosen the soil around the plant to pull it up without leaving the plant’s base behind.
- Soil bars, also known as rock picks, digging bars, or caliche bars, also work well for removal.
- Plants that are pulled up should be placed in trash bags and placed with other trash items to be collected by the city.
Phalaris arundinacea, or reed canarygrass, has native as well as non-native strains in the United States. Asian and European varieties have been introduced and grown for livestock forage and wastewater pollution control.
The non-native varieties and hybrids of non-native and native varieties are aggressive in several environments and have the potential to shade out and displace desirable plants. It’s very competitive, once established, and will often develop a solid monoculture.
Getting Rid of Reed Canarygrass
- Small stands of reed canarygrass can be eradicated through hand removal by taking care to remove as much of the root system as possible. Even small segments of rhizomes can regerminate. Plants and their parts should be disposed of responsibly, as any of them left in contact with water or moist ground has the potential to resprout.
- Covering and mulching have been proved successful to some extent in removing reed canarygrass. The gardener should cover entire areas with many layers of cardboard and several inches of mulch or heavy woven plastic fabric. The covering should be kept in place for the entire growing season with its edges sealed as shoots of reed canarygrass may grow out from the edges to try to reach the light.
- Chemical treatment includes using selective herbicides. Large infestations will need several applications for a few years. The gardener should follow the instructions carefully.
Few Final Words
Invasive grasses can be a headache for gardeners as well as homeowners. They can soon take over an area and crowd out other vegetation.
Although there are many ways to remove invasive grasses, the best approach is to prevent them from appearing in the first place.
Invasive grasses can damage lawns if no appropriate measures are taken. Most invasive grasses can be prevented by growing denser lawns or using baking soda and certain herbicides.
Also, while using chemical treatment over invasive species, gardeners should remember that more is not always better when it comes to herbicides.
In fact, solutions of herbicides, if made too strong, may lose the ability to injure the target plant. Therefore, they should always follow the recommended rates on the label.