6 Best Pre-Emergent For Poa Annua | How & When To Use Them

Poa Annua is a species of self-seeding turfgrass, more commonly known as annual meadow grass or bluegrass. Different from “Kentucky” bluegrass (Poa pratensis), Poa Annua is native to temperate climates, yet can survive in severe climates as well.

Due to its aggressive growth habits, Poa Annua was recently included in the Global Compendium of Weeds. Its delicately plumed pods can send an undesirable cache of seeds in the direction of our carefully curated lawns, leaving unsightly brown patches at the end of its life-cycle.

While we can’t control where the wind takes those seeds, we can manage where they land by employing the best pre-emergent for Poa Annua. After all, preventing growth and seed production ultimately means preserving our healthy lawns. 

Choosing The Best Poa Annua Pre-Emergent

It’s important to understand exactly what a “pre-emergent” does. Unlike weed killers, which are designed to eliminate weeds during active growth, pre-emergents focus on blocking the growth of newly emerging seedlings by inhibiting roots or attacking the plant itself at the cellular level.

The best choice for combating weeds will depend on what your end goals are. Are you looking to prevent seed germination or eliminate existing weeds? If you want to accomplish both, I’ve discovered a couple of effective options that are formulated for double duty.

Poa Annua Identification

So, how do you know if you have a Poa Annua infestation? A noticeable difference in color is the first give-away. This weed displays a lime green hue against the darker green of a healthy lawn. It also grows in clumps with blades stemming from a center point rather than individual blades. The final tell-tale sign is the pale spray of seed pods that emerge toward the end of its life cycle.

Poa Annua Vs Crabgrass

It’s easy to tell the difference between Poa Annua and crabgrass if you know what to look for. Poa Annua blades are very similar in shape and size to those of well-managed lawns — singular, slender ribbons of green. Crabgrass also grows in clumps but, in contrast, looks very much like miniature corn stalks with several cupped leaves growing along a single stem.

Why Is Poa Annua Bad?

Compared to other weeds, Poa Annua seeds are difficult to eliminate because these bothersome plants can withstand being mowed down to less than 1 inch. They can also quickly recover by immediately producing new seeds just days after. In fact, removal attempts via mowing give them the motivation to multiply even faster.

Poa Annua Infestations

An infestation of Poa Annua is evident by large patches of light green on an otherwise dark green lawn, followed by unsightly fronds of seed heads that are taller than the rest of your grass. According to the University of California, it only takes a few established plants to quickly dominate an entire lawn or garden.

Why Does Pre-Emergent Stop Poa Annua?

Pre-emergents specially formulated for this type of weed create an herbicidal roadblock below the soil surface where seeds embed themselves. This prevents sprouting seeds from growing roots and thriving. For more advanced infestations, there are pre-emergent options on the market that contain added weed-eradicating ingredients to further eliminate any that have survived and matured.

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Pre-Emergent Herbicides for Poa Annua Reviewed

After a lot of testing and in-depth research (and many thanks to my lawn for being such a good sport!), I’ve compiled a list of the top six preventative weed killers on the market that demonstrated the highest level of effectiveness.

My criteria were performance, ease of use, and value for money. I’m confident that you’ll find the best pre-emergent for Poa Annua growing in your lawn below.

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1. Scotts WeedEx with Halts Pre-Emergent Weed Control for Lawns

Features:

• Active ingredients: Pendimethalin
• Target weeds: Poa Annua, Crabgrass, Foxtail, Spurge, Oxalis, Henbit, Chickweed  
• Application: Spreaders
• Formulation: Ready to Use
• Action time: Approx. Two Weeks
• Rainproof: Yes
• Coverage area: 5,000 sq. ft.
• Use: Lawns

My list starts off with a highly recognizable brand. I was really interested to see how Scotts performed, and I started with this one because you only need to apply it once when spring temps reach around 13C. One 10lb bag is enough for a large area but, honestly, I only used half of it on my front lawn using a push spreader. The back would be the testing ground for my next pick.

Because pendimethalin is the active ingredient in this, which is toxic to pets and people, I made sure to wear protective clothing while applying. Scotts maintains that you can walk and play on it after. But I would certainly wait a while before rolling around on it. Click here for Scotts Weedex Pre-Emergent from Amazon.com

WeedX works by halting plant cell division. If the cells can’t divide, the plant won’t grow. This process can last up to 9 weeks, which coincides with Poa Annua’s growth cycle. The only downside is that I did see a few new weed clumps popping up. But, per the label, this product may not cover deeply burrowed seeds or those introduced after application.

Pros      

• Only one application needed per season
• Prevents growth and seed formation for up to nine weeks
• One bag covers up to 5,000 sq ft.

Cons

• Depending on severity of infestation, more than one bag may be needed

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2. Scotts Crabgrass Pre Emergent Control for Lawns

Features:

• Active ingredients: Pendimethalin
• Target weeds: Crabgrass, poa annua, goosegrass, and henbit
• Application: Spreaders
• Formulation: Ready to Use
• Action time: Approx. Two Weeks
• Rainproof: Yes
• Coverage area: 5,000 sq. ft.
• Use: Lawns

As mentioned already, I tested this one on my back lawn. The difference between this product and the first is their target and frequency of application. WeedEX is better for Poa Annua and this one targets crabgrass. But it could also affect Poa weeds as it contains the same active ingredient, pendimethalin, while needing to be applied twice rather than once.

After donning protective clothing, I applied the whole bag over my back lawn using my push spreader once the temperature reached 13C in spring. In time, I saw far fewer crabgrass and Annua clumps (still more than on my front lawn, though). This may be due to the amount I put on per sq ft and the increased size of my back lawn. If you do the math, this was actually a win. And I will definitely be trying this product again, maybe applying a little more per sq ft.

Scotts Crabgrass Pre-Emergent works in a similar way to WeedEX by halting plant cell division. However, it’s formulated to focus on the biology of crabgrass. But again, per the label warning, this product may not cover deeply burrowed seeds or those introduced after application. Check Scotts Crabgrass Pre-Emergent Prices from Amazon.com

 

Pros      

• Effective on crabgrass as well as other grassy weeds
• Prevents both spring and winter seedlings with just 2 applications
• Stops crabgrass at cellular level

Cons

• May not effect weed seeds deposited weeks after application

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3. The Andersons Barricade Pre-Emergent Weed Control

Features:

• Active ingredients: Prodiamine
• Target weeds: Crabgrass, poa annua, goosegrass, and henbit
• Application: Spreaders
• Formulation: Ready to Use
• Action time: Immediately after watering in
• Rainproof: Yes
• Coverage area: Covers up to 5,800 sq ft (18 lb)
• Use: Lawns

I really appreciate that Andersons’ Barricade eliminates grassy weeds growing in garden beds, as well as lawns, without harming ornamentals. So, that’s where I chose to test this. I recommend reading the plant list on the bag, to ensure your border plantings are safe. Click here to view The Andersons Pre-Emergent Weed Control.

After not weeding my beds the previous fall, I spread Andersons’ granules around my beds using a hand spreader and wearing protective clothing. The active ingredient Prodiamine is a selective, contact herbicide formulated to control the unique biology of weeds with no significant effect on agricultural crops or garden plantings.

You do need to water this one in because only weeds that come into contact with the granules and water will be eliminated. It’s also important to note that your lawn will be safe for people and pets once these granules are watered in and allowed to dry.

Within a week, I saw unsightly weeds shriveling away, leaving my plants and flowers untarnished. The only drawback was the stains made by granules that settled into the crevices of the stones that line my borders. Make sure to sweep any stragglers into the target area to avoid this.

Pros      

• Effective on crabgrass, poa annua, goosegrass, and henbit
• Beneficial on lawns and garden borders
• No significant impact when used around in border plantings

Cons

• Must be watered in to facilitate activation

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4. Quali-Pro Prodiamine Pre-Emergent Herbicide

Features:

• Active ingredients: Prodiamine
• Target weeds: Poa Annua, chickweed, crabgrass, goosegrass, henbit and others
• Application: Backpack or handheld pump sprayer
• Formulation: Mix with water prior to use
• Action time: Immediately after watering in
• Rainproof: Yes
• Coverage area: Between 9,000 – 44,000 sq. ft.
• Use: turfgrass, lawns and around landscape ornamentals, trees and shrubs

Similar to Barricade, this option from Quali-Pro can also be applied to lawns and ornamental beds and needs to be watered in. What I really liked was the expanded formulation to include the elimination of a larger list of weeds and invasive grasses. Because of the different application methods (handheld sprayer vs. spreader), one 5lb bottle is good for up to a whopping 44,000 sq ft. This means multiple applications for the same price if you have a smaller space to treat.

Keeping in mind that these yellow granules focus on preventing weed seed germination and not already growing weeds, I tested Quali-pro’s selective herbicide on some perennial borders that encase a small section of lawn, where weed seeds had already been ejected by the plants and were about to erupt. Because this product keeps working for up to 6 months, it was a while before I could document its full effect.

While initial skin exposure can result in irritation or rash, your lawns and garden areas will be safe for all to use after watering the product in and allowing it to dry. Click here for Quali-pro Pre-Emergent Herbicide here

Pros      

• One 5lb bottle good for up to 44,000 sq ft or multiple applications
• Great value for money
• Prevents seed germination in a broad range of weeds

Cons

• Not for use on already established weeds

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5. Bonide DuraTurf Crab-Grass Pre-Emergent Control for Lawn

Features:

• Active ingredients: Dithiopyr
• Target weeds: Crabgrass, Barnyardgrass, Black Medic, Chickweed, Foxtails, Goosegrass, Henbit, Oxalis, Pigweed, Purslane, Ryegrass and Spurge
• Application: Spreader
• Formulation: Ready to Use
• Action time: Immediately after watering in
• Rainproof: Yes
• Coverage area: 9.5 lbs, treats up to 5,000 sq. ft.
• Use: Lawns and Ornamental Beds

The fact that this weed eliminator from Bonide also covers a long list of weeds, in both lawns and garden beds, was a plus. While it doesn’t cover as large of a surface area, the easier method of application was attractive. See prices for Bonide DuraTurf Crabgrass Pre-Emergent for Lawns at Amazon.com

Covered in protective gear the following spring, I spread this on my front lawn and flower beds once it warmed up to around 13C. When weed seeds germinate and form roots, the active ingredient, Dithiopyr, prevents those roots from developing any further by blocking cell division and growth with just one application. This effect can last for up to four months.

All this, plus it doesn’t stain pavement or border stones. The only downside is that, depending on the severity of your weed infestation, more than one bag may be needed. And, due to the dust that arises during the application, it’s recommended to wait a day or so before spending time in the targeted areas.

Pros      

• Blocks root growth in a broad range of weeds
• One easy application needed for the whole season
• Doesn’t stain sidewalks or paving stones

Cons

• More than one bag may be needed, depending on infestation severity

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6. Fertilome Turf & Ornamental Weed and Grass Stopper

Features:

• Active ingredients: Dithiopyr
• Target weeds:  Poa Annua, crabgrass, oxalis, henbit, chickweed, and others
• Application: Spreader
• Formulation: Ready to Use
• Action time:  Immediately after watering in
• Rainproof: Yes
• Coverage area: Up to 3,500 to 5,000 sq. ft.
• Use: Lawns, Trees/Shrubs, Garden/Plants

My last pick is from Fertilome. I applied this before I fertilized my lawn (you don’t want to feed the weeds!). Tilling will loosen any embedded weed seeds and bring them to the surface. Again, I do recommend that you read the list of plants this can be used with found on the bag. 

It does need to be watered in but, again, I don’t mind that. I also found that, since this should be applied a couple of times a year, the larger bag is more economical. View Fertilome Turf & Ornamental Weed & Grass Stopper here.

The active ingredient, Dithiopyr, prevents roots from growing as they emerge from the seed. This ingredient is also why you’ll want to wear protective clothing when applying with your spreader. Once watered in and dry, your lawn will be safe to walk and play on.

The only real downside is that you have to time the application correctly for it to be effective. Just follow the instructions in terms of timing and you should get great results.

Pros      

• Easy to apply
• Prevents roots from growing and spreading when applied in spring and fall
• Prevents weeds prior to planting in borders

Cons

• Must be applied at specific times for full effectiveness

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When To Apply Pre-Emergent For Poa Annua

Most of the products I’ve reviewed are recommended for use in the spring and fall. Poa annua, specifically, tends to sprout in the fall. This would be the most effective time to apply your pre-emergent to eliminate this type of weed.

When Does Poa Annua Germinate?

Poa weeds are considered winter annuals. This means their seeds will germinate in late summer or early fall when the temperature drops below 21C. Seedlings will then mature and retreat into a dormant state until spring when they flower and reproduce. It’s best to eradicate them prior to dormancy.

How To Apply Pre-Emergent Weed Killers

Pre-emergents can easily be applied either by granule spreader or with a handheld sprayer if using a water-soluble option. Some will need to be watered in after application, while others will not require it.

Verdict: Eliminating Poa Annua With Pre-Emergent

The common benefit of all six of my recommendations is that they are all effective in eliminating weeds. Different active ingredients and application methods are used to approach this from different angles. This gives you the flexibility to choose one that fits your individual needs and end goals. 

So, now, it’s over to you to decide. Will you go for my first choice of Scotts Weedex Pre-Emergent? Not only does it target Poa Annua and other winter weeds but it will also effectively eliminate other grassy and broadleaf weeds. Or will it be Scotts Crabgrass Pre-Emergent Control that is effective at stopping Poa Annua and will also target crabgrass? Or do you need to eliminate weeds in your borders as well as your lawn? In that case, you will need Andersons’ Barricade Pre-Emergent.

Poa Annua Weed Control FAQ’s