Poa Annua Identification Guide (Look for these 5 things!)

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Poa Annua is also known as annual bluegrass, and it can cause problems in lawns. You just need to learn a little bit about what it is and how to identify it, and then you can control it. Take a look at what you need to know to control it in your yard.

What Does Poa Annua Look Like?

What Does Poa Annua Look Like? Poa Annua tends to grow in clumps in a bunch pattern. It has tall, tasseled stalks that stand above the grass. Poa Annua has bright green leaves with a pointed tip. It also produces a white feathery seed head in the spring and early summer. 


What Is Poa Annua?

Poa Annua is annual bluegrass, and it is a weed that appears in lawns and gardens. It can be difficult to control because it produces hundreds of seeds each season, and they can stay dormant in the soil for several years.

When you are trying to identify weeds in your lawn, look for a tall, tassel seed stalk that is higher than the rest of the grass. It usually shows up in late spring or early summer, and it produces seeds even after you cut it.

One of the problems with this weed is that it will die in the heat of the summer, and it leaves behind brown patches in your lawn. Then, it comes back in the cooler weather when other lawn grasses are dying, and it will take over the lawn for the next season.

Annual bluegrass in turf. Photo: Betty Marose

Five Things to Look for in Identifying Poa Annua

  1. Tall, tasseled stalks standing above the grass
  2. Appears in late spring or early summer
  3. Grows in clumps in a bunch pattern
  4. Smooth bright green leaves with a pointed tip
  5. Produces a white feathery seed head in the spring and early summer

Features of Poa Annua

The key to controlling Poa Annua is knowing where and how to identify it. Take a look at what you need to know.

First, you need to be able to recognize Poa Annua. It has a distinct look that is different from the grass in your lawn. First, it grows in clumps and bunches. It doesn’t grow as individual blades, so you will see thicker areas where Poa Annua is growing.

The leaf blades are smooth with a boat-shaped tip, and you may notice that they wrinkle in the middle of the blade. They are bright green and will be brighter than your lawn grass. There aren’t any auricles, and the leaves grow folded in the bud.

It will grow in rounded clumps, and you will notice the white seed heads in late spring or early summer. It can spread very quickly and take over your lawn. You won’t be able to get rid of it by mowing because the patches are dense and can withstand even low mowing heights.

What Happens When it Dies Back?

When Poa Annua dies back, it will leave brown patches in the lawn. You will find it in lawns, on golf courses, or in vegetable gardens. Once it invades, it produces so many seeds that it will stick around for years to come.

Although it dies back in the heat of the summer, it comes back when the temperatures get cooler. The rest of the lawn starts dying back, and it becomes vulnerable to this invasive lawn weed. It is native to Europe, but it is found throughout the world today.

It only takes a few of these plants to establish themselves in your lawn because they spread quickly. It is important to locate the spots that die back in the summer and treat the area to try to minimize future damage to your lawn.

Poa Annua Coloring

When Poa Annua grows, it has bright green leaves. The blades are fine, and it is a low growing grass. You will notice it because it is much brighter than your lawn grass. When the seed heads grow, they are a whitish color. You will see them on the tips of the blades, and the series of white seed heads come off the leaves.

When the Poa Annua dies back in the heat of the summer, it will start turning brown. During this time, it is much easier to notice. The leaves will brown, and you will see patches throughout the lawn. Then, when your lawn is dying back during cooler weather in the fall, you will notice Poa Annua growing in with the bright green leaves again.

Other Identifiers

In addition to the color, when you look for Poa Annua, you are looking for tall stalks that are tasseled with whitish seeds. The leaves are thin with a boat-shaped tip, and you often see a wrinkle in the middle of the blade.

Look for this weed to grow in clumps and bunches. You can especially find it in wet, cool, or shaded areas of the lawn. The leaves are folded in the bud of the grass, and it doesn’t have any auricles. It is often called a winter annual because it thrives in the cooler seasons, but it produces seeds all through the growing season. In fact, each plant can produce as many as 100 seeds that will survive dormant for several years. This is one of the reasons that it is so difficult to eliminate this weed completely.

You might notice a few plants close to each other. It spreads by releasing seeds, so it will grow out from the initial plant. It spreads very quickly, and it can withstand low mowing.

When Are You Likely to See Poa Annua?

You are most likely to see Poa Annua in cooler weather. It grows in the spring and early summer, and it dies back in the heat of the summer. Then, it germinates in the late summer or early fall after the soil temperatures are lower than 70 degrees Fahrenheit.

The seeds mature in the fall, and they spend the winter in a vegetative state. They will flower and produce seeds in the late spring and early summer. Poa Annua produces a lot of seeds, and they can do it at any mowing height. It grows best when the days are short and the weather is cool. It thrives in moisture, and it can handle compacted soil.

Other Weeds That Resemble Poa Annua

There are a few weedgrassess that are similar to Poa Annua, and it is easy to mistake them for one another. Take a look at weeds that resemble this invasive grass.

Poa Trivialis

Poa Trivialis is also called rough bluegrass, and it is a perennial grass that also tolerates shade. It does well in cool weather, and it loves moisture. It also dies back in the heat of the summer. However, the stems of this plant survive underground and wait for cooler temperature before it rises up again.

It is light green and makes a thick bunch of stems, which choke out the lawn. It can leave large brown patches in the summer, and it almost looks like a fungal infection in the lawn. These seeds are also similar to Poa Annua, so it is hard to tell the difference.

Final Words

The key to controlling and maintaining your lawn is to identify weeds and implement a plan. Poa Annua is a common wheatgrass that can take over a lawn very quickly. You can look for it in clumps and bunches in the lawn, and it has a taller green stalk with whitish seeds. It will die back in the summer, but the seeds can lay dormant for up to two years.

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