How do you kill poa in bluegrass?

I can kill Poa annua in bluegrass with Ortho Grass B Gon Garden Grass Killer. This product is a non-selective herbicide that is specifically formulated to kill grassy weeds, like Poa annua, in bluegrass. It works by penetrating the weed’s foliage and entering the root system, killing the grass down to the roots. The key points to remember are:

• Kills Poa annua in bluegrass

• Non-selective herbicide

• Penetrates weed foliage and enters root system

• Kills grass down to the roots

Best Ways to Kill Poa Annua

Poa annua, also known as annual bluegrass, is a common weed in lawns. It can be difficult to get rid of, but there are several methods that can help. Here is a comparison table of the best ways to kill Poa annua:

Method Advantages Disadvantages
Herbicide Effective at killing Poa annua Can be harmful to other plants and the environment
Mulching Can prevent Poa annua from growing Can be costly and labor-intensive
Manual removal Can be done organically Time-consuming and may not completely eliminate Poa annua
Irrigation management Can prevent Poa annua from growing in areas with proper drainage Can be difficult to implement in poorly drained areas

Understanding Poa Annua

Poa annua is a common weed species found in turfgrass areas. This invasive grass can cause significant damage to your turf and outcompete the desirable grass species. Learning the characteristics of the plant and properly managing it is key for successful control.

This article will provide an overview of poa annua, covering its identification and the best strategies for controlling it.

Identifying Poa Annua

Poa annua, commonly referred to as annual bluegrass, is a cool-season grass. It has the ability to propagate by both seeds and underground rhizomes and forms a tight sod or turf. It prefers moist, shady areas and can often be found in urban yards since it tolerates various soil types and is resistant to low temperatures and foot traffic. Poa annua also tends to spread quickly— making it considered an invasive species in some areas—and can push out more desirable turf grasses due to its prolific growth rate.

Identifying Poa Annua can be difficult since the grass is self-seeding, meaning that different stages of growth on one area can look drastically different from each other at any given time of year. Fortunately, there are a few key characteristics that can help all gardeners with Poa Annua identification:

  • It has relatively shallow roots
  • The blades are light green or yellowish in color
  • Has a softer texture compared to most other turfs
  • Roots produce flowers on stalks that have 2–3 seed heads with large powdery grains
  • Grows widely in a variety of climates and soils

In addition, Poa annua grows in “patches” which means the grass will cluster together rather than spreading evenly throughout the lawn like other traditional varieties of turfgrasses.

Life Cycle of Poa Annua

Poa annua, a creeping winter grass commonly used in lawns and golf courses, belongs to the family of cool-season turf grasses. It is one of the most prevalent weeds in landscapes and is notorious for its ability to rapidly spread across lush surfaces. Understanding the Poa annua life cycle can help you prevent it from overpopulating your space and take action against it if needed.

Germination: Poa annua will start germinating once the soil temperature drops below 50 degrees Fahrenheit (10 degrees Celsius). These annual seeds typically staple onto exposed soil, skip passing through its vegetative form, and immediately move onto flowering and seeding in fall or early spring.

Flowering: When regular fertilizing resumes or during a mild spell or warm temperatures in late winter, look for flowers on Poa plants. Identification is easy due to the unique colors of the small pale blue flower head with three long feathery stigmas protruding out from the center.

Seed Production & Dispersal: Fully developed seed heads contain small oval-shaped grains, or seeds, that remain dormant until environmental conditions become ideal for growth. As soon as flowering ends in spring and summer, these seeds take large numbers of hops away from inflorescence allowing them to disperse over great distances up to six feet away before settling down on moist soils in late autumn or early winter where they restart the cycle again.

Preventing Poa Annua

Taking the right preventive measures is critical to controlling and preventing Poa annua in your lawn.

Method Advantages Disadvantages
Proper fertilization Can promote growth of desired turfgrass species Can be costly and labor-intensive
Proper mowing Can prevent Poa annua from developing seed heads Can be time-consuming
Proper irrigation Can prevent Poa annua from growing in areas with proper drainage Can be difficult to implement in poorly drained areas
Proper aeration Can help reduce thatch buildup and improve soil health Can be costly and labor-intensive
Proper soil pH Can prevent Poa annua from growing Can be difficult to maintain and monitor

Maintaining Proper Soil pH

Poa annua (annual bluegrass) prefers soils of low fertility and acidic pH, with levels below 6.5 best for preventing its occurrence in a lawn. To prevent and manage this weed, start by properly testing the soil’s pH levels with a basic soil test kit. Aim for a soil pH that ranges from 6.5 to 7.0 and maintain it through proper fertilization practices, applications of lime or sulfur as needed, and careful consideration of the characteristics of your local water supply.

Once you’ve adjusted your soil’s pH or verified that it’s at an appropriate level, you can establish an effective maintenance strategy by making sure that your lawn receives ample water and fertilizer during the cooler months when poa annua growth is most active. This will help to create denser grass cover which can shade out any potential poa annua seedlings before they have a chance to take hold in your lawn.

In addition to watering, fertilizer should also be applied appropriately throughout the year as both nitrogen and phosphorus are important nutrients for promoting healthy growth in bluegrasses such as Kentucky bluegrass and this will help reduce infestations by aggressive weedy species like Poa annua that prefer fertility-poor soils.

Proper Mowing Practices

This grass type can better survive low mowing heights than other turfgrasses and can often take over a lawn quickly. To control poa annua, proper mowing practices should be used.

Mowing should occur at a height of no lower than 2 ½ inches for bluegrass or Kentucky bluegrass varieties. This height discourages the germination of poa annua seeds that may have come into the turf via other sources such as birds or wind dispersal. Additionally, this cutting height will encourage more vigorous growth of desirable grass species and limit competition from the poa annua by preventing it from receiving enough light energy to produce high-quality seed heads.

It is important to remember the following:

  • Not scalp the lawn and remove more than one-third of the leaf tissue when mowing because this opens up opportunities for undesirable grass types such as poa annua to invade your lawn.
  • Be sure to only use sharp blades for mowing as this reduces damage done to individual grass blades, which also helps with uniformity and prevents disease infestations.

Properly maintaining your turfgrass through shrewd mowing practices can help you keep poa annua down in check year-round!

Fertilization Practices

Fertilization is one of the key steps to effectively managing your lawn and controlling Poa Annua. Adding the proper nutrients to your grass will prevent Poa Annua from dominating as it results in the loss of marginal habitat.

The type and amount of Nitrogen that is applied should be adjusted throughout the year depending on the season and cool season grass species, such as Kentucky Bluegrass. Generally, the cool season grass needs 1 to 2 lbs of Nitrogen per thousand square foot annually, so if you are using fertilizer with a higher Nitrogen content (N-P-K ratio). The application should be split into 2 – 4 applications over 6 to 8 weeks. It is best to apply nitrogen fertilizer late in spring or summer when temperatures have warmed up [x]. Using a slow release nitrogen source helps eliminate burn risks even farther. Applying higher acids such as calcium nitrate or ammonium sulfate can also be effective in controlling Poa Annua [y].

Beyond nitrogen application other practices that can help reduce Poa Annua include:

  • Raising he mowing height
  • Vertigration practices are recommended when possible as this practice will help create competition for resources normally held by poa annua which in turn helps crowd out poa annua[z].

Killing Poa Annua

Killing Poa annua is necessary when it begins to outcompete bluegrass and other desirable turfgrasses. Poa annua is an annual grass that can quickly take over a lawn and is best treated with a combination of cultural practices and herbicides.

In this article, we will discuss how to properly kill poa annua in bluegrass for best results:

Selective Herbicides

When trying to control Poa annua, selective herbicides are the most effective solution. These types of herbicides use a chemical agent that specifically targets and kills the desired weeds without harming the surrounding desirable or non-target species. Selective herbicides can be pre-emergent or post-emergent and vary depending on the application.

Pre-emergent Herbicides
Pre-emergence herbicides kill weed seeds before they germinate and establish roots in the soil. By preventing germination, this type of chemical controls Poa for several months at a time and is usually applied on bare soil without vegetation present. Timing is important with this type of product because weeds must come into contact with an active ingredient in order for it to be effective against them.

Post-emergent Herbicides
Post-emergence herbicide works well at controlling isolated patches of Poa annua after it has already germinated. It is best used as a spot treatment when actively growing so it can effectively target specific areas within bluegrass lawns where Poa has become a problem. It is important not to broadcast spray post-emergent products randomly because they do not discriminate between desirable plants and target weeds, which can cause damage to desirable species.

Non-Selective Herbicides

Non-selective herbicides, such as glyphosate, are an effective way to kill poa annua. Glyphosate is a broad-spectrum, post-emergence non-selective herbicide that kills all grass and weed species it touches. It works by interfering with the production of important proteins in plants necessary for growth and development.

This method of killing poa annua is successful because it targets actively growing weeds during periods of active growth.

Glyphosate should be applied when poa annua is actively growing and should be applied according to the manufacturer’s instructions before the product degrades. For optimum control, glyphosate should be:

  • Reapplied every 6 weeks until desired control is achieved;
  • An additional application may be necessary if there are weather delays or overuse of preemergent herbicides.

When using any type of herbicide it’s important to read and follow all label instructions carefully in order to avoid damaging desirable turfgrass or other plants in the lawn or landscape.

Cultural Practices to Control Poa Annua

The most effective means to control this weed is through a disciplined combination of cultural practices. These include mowing at the proper height and frequency, application of protective fertility, and watering appropriately.

Mowing Poa Annua
The primary cultural control for Poa annua is periodic mowing. Proper mowing height and frequency are critical for preventing the establishment of seedheads. The minimum recommended mowing height for bluegrass is one inch or less depending on the turf species you want to maintain in your lawn or athletic surface. Homeowners should set their mower blades no higher than 2 inches above the ground; golf courses should adjust their cutting heights according to maintenance plans and put green heights. Mow at least twice per week during hot summer months when Poa populations become more problematic due to increased seed production.

Fertility Requirements
Basic fertility requirements needed to maintain a healthy stand of turf will also help ensure an unhealthy environment for Poa annua growth by promoting root development of desired plant species that out-compete it for resources like water, light, and nutrients hence eliminating its presence in the field or lawn. It can also weaken its ability to produce viable seedheads if competition is strong enough from healthy turf stands due to competing root systems made up mostly of desired turf varieties like Kentucky Bluegrass or Fine Fescue grasses which reduces its success at propagating itself.

It is important not to water too often or too deep as this encourages over-lush growth which weakens both dense grasses stands as well as individual plants allowing poa annua a greater opportunity to propagate itself successfully by exposing open spaces between densely vegetated areas of natural obstructions such as rocks or stones create which interfere with shoot emergence thereby reducing competition from desired turf varieties helping keep poa under control until other management tactics weigh in effectively on site.

Does poa annua go away on its own?

It is true that Poa annua may die off on its own during the summer months when the weather gets hot, but it may also leave behind bare spots in your lawn.

  • Germination: Poa annua germinates in late summer or early fall. The seedlings grow throughout the fall and then flower the following spring. So, the plant can reappear again next year if not treated.
  • Death in Summer: Poa annua usually dies off in the summer when the weather gets hot. This can be an advantage as it will leave behind bare spots in your lawn, however, this does not mean it will not come back next year.
  • Prevention: Implementing preventative measures such as proper fertilization, mowing, irrigation, and aeration, can help keep Poa annua from becoming established in the first place and prevent it from re-appearing next year.
  • Herbicide: Using herbicides can be effective at killing Poa annua, but it may require multiple applications and proper timing for best results.

In general, Poa annua can be a difficult plant to control and it may require a combination of methods to keep it under control.


After taking into account all the above factors, it can be concluded that the best way to kill poa in bluegrass is to use a pre-emergent herbicide. By treating the soil with a preemergent herbicide, you can prevent weeds from germinating in the future and prevent poa from taking over your lawn.

Other methods such as manual removal, overseeding, and mowing can also be employed to reduce the poa population in your lawn.

Summary of Strategies to Control Poa Annua

Control of Poa annua or “annual bluegrass” requires an integrated approach that requires strategies such as cultural and chemical control. To successfully reduce or eradicate Poa annua from turfgrass, develop a plan that includes appropriate cultural practices and adequate chemical controls when necessary.

Cultural Practices

  • Mowing height: Mowing heights between 1½ and 2½ inches can help reduce Poa annua presence by limiting seedhead production.
  • Fertilization: Improper fertilization with heavy nitrogen applications can increase the competitiveness of existing annual bluegrass weeds. Therefore, it is important to follow the recommendation of the soil test report when creating a fertilization program or plan.
  • Growth Regulators: Growth regulators (e.g., paclobutrazol) may be used to limit the vertical development of weeds in turf, such as Poa annua and tall fescue; however, some researchers have reported unsatisfactory weed control results with this practice.
  • Overseeding/Renovation: Overseeding turf with desirable grass species can help establish competitive vegetation in areas heavily infested with annual bluegrass, reducing its presence over time.

Chemical Control

Preemergence herbicides are generally applied two to four times per season for annual bluegrass suppression in high-input turf from late summer through late spring on the east coast; however, some postemergence herbicides may also be included within this program for comprehensive weed management plans. Principal active ingredients for preemergence control found on numerous products include benefin + trifluralin (TF) mixtures; oxyfluorfen (OXF); dithiopyr (DT); prodiamine (PRD); snapshot® 2.5TG; pendimethalin+dithiopyr mixtures; pyrithiobac (PTD); atrazine+simazine mixtures; dimethenamid-P+oxadiargyl mixtures; DCPA+dimethenamid-P mixtures and oxadiazon(KIC). When selecting a chemical treatment product, it is important to understand factors such as turf species, time of year application will be done, target weed that should be controlled, desired longevity of control, local weather conditions, and other restrictions before selecting a product or making an application.


Frequently Asked Questions

Q1: What is poa in bluegrass?

A1: Poa, or Poa annua, is a common weed in bluegrass lawns. It is a grassy weed that can be difficult to remove once it has established itself.

Q2: How do you get rid of poa in bluegrass?

A2: The best way to get rid of poa in bluegrass is to use a combination of cultural and chemical control methods. Cultural control methods include mowing regularly and making sure the lawn is adequately fertilized and watered. Chemical control methods include using pre-emergent herbicides and post-emergent herbicides to kill the poa.

Q3: Is it possible to kill poa in bluegrass without using herbicides?

A3: Yes, it is possible to kill poa in bluegrass without using herbicides. Cultural methods such as mowing regularly and providing adequate fertilization and water can help to reduce the spread of poa. In addition, there are some organic methods such as using corn gluten meal or white vinegar that can be used to kill poa.






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