How to Remove Poa Annua From Your Lawn

A weed that can easily be mistaken for Kentucky bluegrass is known as Poa annua, or annual bluegrass. Poa weed is a grassy weed that’s extremely common throughout the United States and is well adapted to various locations, conditions and maintenance practices making it a weed that can be tough to get rid of.

Is Poa annua a weed?

Poa annua, or annual bluegrass, is in fact a weed. In fact, Poa annua grass is one of the more notorious weeds due to how difficult it is to control in both residential and professional settings. It’s technically a cool season grass but is often considered a weed throughout many areas of the United States.

Poa Annua Identification

Perhaps the easiest way to identify Poa grass is by its tall seed head which produces tassels and rises above the typical home lawn. Poa annua grass is light green in color, making it stand out in most other grass types which can contribute to the “patchy-look” in lawns.

Pictured above from left to right: A closeup of Poa annua with its tall seed heads and a photo of what Poa annua might look like in a residential landscape.

How to Get Rid of Poa Annua

If you’ve identified Poa annua early on and only a few weeds are present, it can be pulled by hand and may not grow back again. However, if Poa annua turns into a recurring problem or is too extensive to pull by hand, there are many chemical options that serve as Poa annua herbicides. One method for controlling Poa annua is by using a pre-emergent or post-emergent herbicide.

How to Kill Poa Annua

Chemical control is often the best approach if Poa annua has spread throughout your entire lawn. While there are many herbicide options available, they will typically fall under one of the following categories: pre-emergent herbicides and post-emergent herbicides. Both types are typically necessary for controlling Poa annua since it’s such a tricky weed.

Start by using a pre-emergent herbicide to prevent Poa…it’s more effective.

Pre-emergent herbicides are used to prevent weeds from appearing while post-emergents are used to treat currently existing weeds. Use pre-emergents before the first frost in your area in the fall and before soil temperatures reach 70 degrees Fahrenheit. Pre-emergents are often the most effective method for controlling Poa annua. Once it appears in your lawn, it becomes harder to control. Learn more about fall pre-emergents here.

Use a post-emergent herbicide when weeds are currently present.

If Poa annua has already established itself, the question then becomes “what kills poa annua?”. A Poa annua post-emergent herbicide will be necessary at this point in the game. Even if you applied a pre-emergent on time, it’s good to apply a post-emergent to kill any current Poa annua weeds before they begin spreading—and they can spread pretty fast.

A few Poa annua killers are Hi-Yield Atrazine and Tenacity. Revolver is also a good option.

If nothing else works, spot-treat the weed with a non-selective herbicide.

This is often a last resort option and should be optional. If you’ve applied both a pre- and post-emergent herbicide and still see Poa annua, consider spot-treating it with a non-selective herbicide. 

Non-selective herbicides will kill all vegetation it comes in contact with, which is why you should spot-treat with it for the purposes of killing Poa annua. You’ll use a liquid non-selective herbicide, tank-mix it in a spray-tank and apply directly to the weed with a nozzle.

Selective herbicides, on the other hand, only kill the weeds listed on their product labels.

When Poa annua cannot be controlled by maintenance practices alone and a chemical must be applied, make sure to read the label carefully to ensure that it will not cause any damage to your lawn and is compatible with your type of grass. This weed is very similar to some grasses commonly found in home lawns and many chemical products can cause damage if the label is not checked before application.

Non-Chemical Control of Poa Annua

In addition to chemical control of Poa annua, there are also many non-chemical strategies that can prevent Poa annua or reduce how much it appears.

Due to its shallow rooting system, Poa annua will thrive in areas of the lawn that are overwatered; therefore, homeowners should attempt to water deeply and infrequently so that the shallow rooting system is unable to obtain the water it needs. 

Most lawns only need around 1-inch of water per week including rainfall. Consider conducting an irrigation audit to provide the different areas in your lawn with the proper amount of water.

It can also be beneficial to raise the mowing height for the lawn, as Poa annua is a shorter plant, which gives the lawn a chance to choke out the weeds.

Creating a lawn that is dense and healthy can prevent weed problems from occurring. This includes maintaining a proper mowing, irrigation and fertilization schedule to meet the needs of the turf so that thin or diseased patches that are more susceptible to weeds do not have the chance to develop. Check out our care guides on individual grass types for more information.

Weeds will struggle to compete against a maintained, established lawn. Proper fertilization can help it develop a healthy canopy that is thick enough to crowd out weeds. Here are some of our favorite fertilizers. You can learn more about them in Why Use Lawnifi Fertilizer?.

Can you pull Poa annua?

Poa annua can in fact be pulled by hand in less severe scenarios and it may not grow back again. However, if Poa annua turns into a recurring problem or is too extensive to pull by hand, chemical options may be the best method of control. 

Where does Poa annua come from?

Poa annua is an annual grass species that’s native to Eurasia. Over time, it became naturalized. It can now be found in Africa, Australia, New Zealand, North America, South America and all major sub-Antarctic islands. It was first classified by Carl von Linné in 1753.

Where does Poa annua grow?

Poa annua can be found in gardens, paths, roadsides, agricultural fields, lawns, golf courses and other professional landscapes. 

As previously mentioned, Poa annua can be spotted in many places around the world. It’s well adapted to various locations, conditions and maintenance practices making it a weed that can be tough to get rid of.

Poa annua tends to prefer areas with a lot of nitrogen and thrives in overwatered landscapes or areas near bodies of water. 

The poa annua weed can also continue to grow in the winter when most home lawns go dormant and will thrive in areas of the lawn that are damp, shady and compact due to its shallow rooting system.

How does Poa annua spread?

Poa annua spreads by seeds that’s carried by wind, foot traffic, mowing, etc. Unfortunately, by the time you spot Poa annua in your lawn or garden, other Poa annua plants are more than likely germinating. This is why preventative control with pre-emergent herbicides are a more effective method of control. 

A single Poa annua plant can produce hundreds of thousands of seeds. What’s even worse is that the seeds can remain dormant in soil for years and germinate later in the future. The amount of seeds produced can make this weed really hard to permanently get rid of.
Poa trivialis, on the other hand, spreads with stolons.

When does Poa annua germinate?

Poa annua grass germinates in the fall when soil temperatures drop below 70 degrees. This is why it’s important to apply a pre-emergent slightly before soil temperatures reach 70 degrees and consistently drop.

Once the germination process begins, the weed will continue to grow throughout the spring and will then flower and die off in the summer. When the weed dies off from the heat of the summer, it leaves behind unattractive brown or bare patches in the lawn.

A single Poa annua plant can produce hundreds to thousands of seeds, which can remain dormant in the soil for years and will typically germinate during the late summer to early fall.

When does Poa annua die?

Will Poa annua die in the summer?

Poa annua grass germinates in the fall when soil temperatures drop below 70 degrees, continues to grow throughout the spring and will then flower and die off in the summer. Unsightly brown patches from the dead weed will be left in its place.

How can Poa annua be prevented?

Pre-emergent herbicides can be used to prevent weeds from appearing. Post-emergents, on the other hand, are used to treat currently existing weeds. Use pre-emergents before the first frost in your area in the fall and before soil temperatures reach 70 degrees Fahrenheit. 

Pre-emergents are often the most effective method for controlling Poa annua. Once it appears in your lawn, it becomes harder to control. Learn more about pre-emergents here.