How to Control Poa Annua in the Lawn

As it produces hundreds of seeds, small numbers can multiply very quickly and can prove very difficult to control.In this article, Eden brings you the ways to control poa annua in your lawn, the causes of poa annua and the other weeds that need to be removed from your lawn.

1. Fertilize Regularly to Control Poa Annua

A healthy lawn can effectively crowd out weeds. Therefore, before considering chemical controls, starting with some cultural practices like proper fertilization of lawns is recommended by Eden. Lawns should be regularly fertilized, about four times a year, so that the soil does not lack any nutrients and the grass remains healthy, keeping the lawn thick and lush, not leaving any room for weeds to sprout.

The appropriate times to fertilize your lawn is during early spring, late spring, summer and fall. Fertilizer applications in early spring allow the lawn to get a boost of energy after the dormant months of winter and late spring fertilizations replenish all the nutrients that a hungry lawn would have soaked up throughout the spring season. 

Jonathan Green Winter Survival Fall Fertilizer is a good option for this or you could use Scotts Turf Builder Lawn Food which is good for use in all seasons but it has a high nitrogen content which can burn your grass if applied unevenly. This is also phosphate free and therefore can be used in states that have phosphorus bans. 

2. Apply a Pre-Emergent Herbicide to Control Poa Annua

The hardiness of the poa annua seeds and the sheer number of them produced every time can make this grassy weed difficult to control without chemical methods. Therefore, pre-emergent applications are recommended by Eden to control poa annua. 

When applying pre-emergent herbicides it is important to do so at the right time for effective control. Poa annua seeds germinate during the fall season and early spring time. Therefore, the fall application of pre-emergent herbicide for poa annua should be when the soil temperatures are consistently below 70 degrees Fahrenheit. 

Eden recommends applying the fall pre-emergent herbicide twice with a gap of six to eight weeks in between. This will ensure that any spots missed during the first application are covered and provide more comprehensive annual bluegrass control for the entire lawn by also impacting any late germinating poa annua seeds.

Another pre-emergent application is required in early spring to control the poa annua seeds from germinating when the temperature rises after winter. The exact time of this application will depend on where you live and you can consult your local county extension office for the information.

Some of the products recommended by Eden for pre-emergent poa annua control are Dimension 2EW Herbicide and The Andersons Barricade Pre-Emergent Weed Control; both these products are selective and do not harm ornamentals. 

Apply a Post-Emergent Herbicide to Control Poa Annua

Post-emergent herbicides should be applied in combination with pre-emergent applications to provide effective control of weed grass seeds that germinate late and also to kill any established poa annua grass. 

But care needs to be taken while applying post-emergent herbicides as they can affect the surrounding grass, depending on the grass type. Poa annua is classified as a weed due to the unsightly white seeds on its stalks and its invasive tendency but it technically still is a cool season grass.

Some of the products recommended by Eden for post-emergent herbicide applications are Quali-Pro Negate 37WG Herbicide and Certainty Herbicide. You can spray the product using a pump sprayer if it is a liquid concentrate for granular post emergent applications you will need a spreader.

Spot Treat Your Yard to Control Poa Annua

Another method to control poa annua in your yard with minimum damage to the surrounding grass, especially if it’s cool-season grass is to spot treat your yard. Find the patches on your lawn where the annual bluegrass is trying to overtake your turfgrass and apply non-selective herbicides to treat the weeds in those patches.

Since these herbicides are non-selective, they will kill the turfgrass wherever they are sprayed. Therefore you need to be careful with their application or you might end up killing all the grass on your lawn and harm the nearby garden plants and ornamentals. Eden recommends reading the label of the product carefully before application to understand how the product will affect your lawn.

Some of the products recommended by Eden for spot treatment of poa annua in your lawn are Roundup products like Roundup Pro Max and Roundup Super Concentrate Weed & Grass Killer. The active ingredient in Roundup products is glyphosate which provides excellent control over poa annua. A pump sprayer can be used to spray the product after mixing the appropriate amount.

Set Your Mower High to Control Poa Annua

Similar to appropriate fertilization, mowing your lawn high is another cultural practice to prevent poa annua in your lawn. Poa annua grows short and therefore, when you mow your lawn high, that is, around three to four inches, this will give your grass a good chance to crowd out the weeds.

A lush, thick and healthy lawn will have very few problems due to poa annua or annual bluegrass. You can use a ruler or a tape measure to set the correct height for your mower deck.

When lawn grass is allowed to grow tall, it will encourage the grass to develop deeper roots which is preferable to extend the life of the lawn and make it disease and pest resistant and to make it choke out the weeds.

When allowing your lawn grass to grow tall, you should be careful to not let it get too tall as this will encourage the presence of insects in your lawn. Mow to keep the height of the lawn between three to four inches and every time you mow follow the one-third rule of mowing with sharp blades.

Avoid Overwatering to Control Poa Annua

The most favorable growing conditions for poa annua are shady areas of your lawn combined with excess moisture as it has shallow roots that are fed with the excess water. Therefore, you should avoid overwatering your lawn, especially in the shady areas so that its shallow roots are not able to receive water to grow.

Check the areas of your lawn that receive a lot of shade to see if the irrigation water you supply to these patches dry up. Due to lack of sunlight, the water that is not absorbed by the soil will not quickly evaporate and remain there for a long time, creating favorable conditions for insects, diseases and weeds.

If you see that the shady areas in your lawn remain moist then it is an indication that you might be overwatering these patches. Therefore, you need to set you irrigation system to supply the amount of water that will get absorbed by the soil and not create wet patches in your lawn.

Eden recommends a deep and infrequent irrigation pattern instead of a shallow one as this has a two-pronged benefit. It will allow all the water to completely dry up before new irrigation water is supplied and also encourage your lawn grass to grow deep roots that will keep the grass healthy and make it resistant to drought conditions. 

What are the Causes of Poa Annua?

Poa annua is a difficult weed to control once it invades your yard but learning what causes it might help you prevent this annual bluegrass from taking over your lawn. Given below are the various causes of poa annua.

• Change in seasons: There are certain seasons that are more favorable for poa annua growth like fall and spring. Therefore, when the season shifts after summer and winter, there are more chances that poa annua will be seen in your lawn. 
• Overwatering your lawn: Too much moisture, especially in the shady areas of your lawn will invite any dormant poa annua seeds in your lawn to sprout as this annual bluegrass prefers shade. 
• Applying excessive fertilizer: Poa annua is technically a cool-season grass. So, any fertilizer that is used to aid turfgrass growth will also enable poa annua to grow. Therefore, you should take care that you only apply fertilizer that is required by your turfgrass and not anything more as the excess will be taken up by poa annua, making it strong. 
• Ease of spreading: Poa annua can enter your yard in various ways – through foot traffic, birds, wildlife, lawn mowing, new plantings, etc. Also, even a single poa annua stalk can produce multiple seeds and these seeds are hardy and sow easily. 

Does Poa Annua Come Back Every Year?

Yes, poa annua comes back every year. Poa annua is an annual that germinates during spring and early fall and the rest of the time, its seeds remain dormant. Poa annua is known as a prolific seed producer that can produce hundreds of seeds that sow easily and are hardy. These seeds remain dormant till the conditions are favorable for sprouting and then germinate immediately. 

What are the other Weeds that Need to be Removed from the Lawn?

Apart from poa annua, there are other weeds that need to be removed from your lawn to maintain the health and quality of your lawn. They are given below.

• Crabgrass: Crabgrass is one of the most common weeds found throughout the U.S. and in southern Canada. It has a prominent midvein out of which flat, minted grass-like blades emerge and they look like a crab’s or a spider’s legs, hence the name. 
• Dandelion: Dandelions are broadleaf perennial weeds that are one of the easiest weeds to identify due to their yellow flowers that transform into white puffballs. The leaves of this weed are lance-shaped and their edges are serrated. 
• Plantain: Broadleaf plantain can be found throughout the U.S. and southern Canada. This is a broadleaf perennial weed that has rosette-shaped leaves. It spreads through its seeds that range from orange to black in color. These weeds can produce up to 15,000 seeds per plant.
• Canada Thistle: Canada thistle is also a common weed throughout the U.S. and some parts of Canada. It is a broadleaf perennial weed that grows upright up to two to three feet tall. It can be identified by pink, purple and white flowers. It is also called creeping thistle and it spreads through root fragments and seeds.
• Oxalis: Oxalis are broadleaf perennial weeds that are found throughout the U.S., mostly along the coastal regions and through the southern part of Canada. They can be identified by their heart-shaped leaves that are plain green in color; they also develop bright yellow flowers in spring. 
• Ground Ivy: Ground ivy is a perennial broadleaf that releases a distinctive odor upon being crushed and it is found in eastern America and parts of Canada. Ground ivy can be identified by its green kidney-shaped leaves and lavender flowers that bloom in spring and summer. It spreads fast through seeds, stolons and root notes and creates a carpet in shady areas, affecting the turfgrass in these areas. Ground ivy is also called Creeping Charlie.

If you are facing issues in your lawn due to poa annua or any other lawn weeds and require professional assistance, you can consult Eden. Our experts are knowledgeable to correctly identify the types of weeds in your lawn and skilled to employ the appropriate control measures while keeping the overhealth of your lawn in mind. If you have any other landscaping queries or are curious about the other landscaping and yard services we offer, you can visit our website or contact us at any of our offices.