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.
A closeup of Poa annua with its tall seed heads and a shot of what Poa annua may look like in a residential environment are shown above, from left to right.
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 growing, and post-emergent herbicides are used to treat weeds that have already emerged. Apply pre-emergents before the first frost in your region and before soil temperatures hit 70 degrees Fahrenheit in the autumn. Pre-emergents are often the most efficient way to manage Poa annua. It gets more difficult to manage after it has established itself in your grass. Learn more about autumn pre-emergents by clicking here.
If nothing else works, use a non-selective herbicide to treat the weed.
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.
Non-Chemical Control of Poa Annua
In addition to chemical management of Poa annua, there are various non-chemical measures that may prevent or limit the amount of Poa annua that occurs.
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 need just around 1 inch of water each week, including rainfall. Consider completing an irrigation audit to ensure that the various regions of your lawn get the appropriate quantity of water.
Raising the mowing height for the grass may also be useful since Poa annua is a shorter plant, giving the lawn a chance to starve out the weeds.
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 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.
Due to its shallow roots structure, the poa annua weed may also continue to grow throughout the winter, when most residential lawns lay dormant, and will flourish in sections of the lawn that are moist, shaded, and compact.
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.