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Ask The Yard Doctor Weeds Lawn Care

I have Poa Annua but not sure what other "undesirable grass" is

last year

I have a lawn that is approximately 29,000 square feet. It is mostly (85-90%) Perennial Ryegrass, which is what I want. I live in Arlington WA, which is in zip code 98223. The house was finished in March of 2016, which is when we moved in. Our house was one of the last ones finished in our development of 21 homes which was forested and cleared for the development. About 6,000 square feet of lawn was sod, installed by the builder, and the rest, which was done in the Fall of 2015, was hydroseeded by a company we hired. They removed a lot of rocks from the soil and tilled in a lot (100 yards?) of compost using a tiller on a Bobcat, before hydroseeding.

Each lot is about 1 acre (~44,000 square feet). Most of the other lawns have been successfully taken over by Poa Annua but I am still trying to keep it from taking over my lawn. The Poa Annua is relatively easy to pull out whole with the roots intact. I do some of it and hire laborers to do some of it. We have in-ground irrigation so I am removing the Poa one zone at a time so I can patch the holes with Perennial Ryegrass seed and Lawn Soil from Lowe's, then run a water-in cycle for that zone. This soil is fine and is easy to sprinkle in a thin layer on the seed. Unlike Peat Moss, it is not acidic so does not promote growth of moss. Last year I did use Peat Moss and this spring had to rake out about 8 of those 95 gallon yard waste containers from just a 6,000 square feet section.

My question today is, what is the "other grass" shown in the first picture? If I try to pull it out, the blades just break off and only a few roots come up, unlike the Poa. I guess I'll have to dig this out but wanted to see if anyone here had advice about an easier or better way to get rid of it. Fortunately I don't have a large amount of it. The second picture shows Perennial Ryegrass. The third and fourth pictures show Poa Annua.

Thanks,

Don

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Comments (3)

dchall_san_antonio
last year
Usually gardengal pops in for lawn issues in the PNW. If she doesn't see this in a day or two, I'll drop her a line.

The other grass in the first picture looks like poa. Whatever you have in the other pix don't look like poa.

Does WA have a lot of restrictions on herbicides? One of the problems with poa is the propensity to drop a boatload of seed and come back stronger next year. Atrazine is a fairly powerful herbicide which kills the poa and its seed, but it is also a carcinogen, so there's that. One approach you might consider to torching it out with a weed flamer from Harbor Freight. They cost about $30 plus you have to have a butane tank. I have one that I use for searing steak, but using it on weeds is the intended purpose. It will burn out the grass and seed in a very localized area like you're seeing in the lawn. Then you can reseed with rye or the surrounding grass once you know what grass you have surrounding the weeds.

You should not need to add any more soil when you seed the new grass. Simply step on the seed to ensure it has contact with the soil and start watering. I fear you're going to have enough problems with a bumpy surface based on what your landscaper did to prep for the new grass (rototilling is a no-no for grass).
FrozeBudd_z3/4
last year
last modified: last year
Possibly could be creeping bentgrass, I removed a very substantial amount from my front lawn by spot spraying with Roundup and later either reseeding or having dug the area out and doing a sod transfer from another section of lawn. If indeed bentgrass, there's a chemical treatment called Tenacity.

I ABSOLUTELY HATE POA |!! ... thankfully, most has slowly died out from my lawn, but it's a horrible pest to keep out of the veggie garden and pathways, it flowers and seeds in a flash and continuously all season long up here in the north!
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Don Anderson
Original Author
last year
Reply to dchall_san_antonio, I guess I failed to adequately explain the magnitude of our lawn installation. Rototilling was a critical part of it. I misspoke when I said the lawn was expanded in 2015. It was 2016. Please refer to the pictures below. The first one with the car shows the lawn area hydroseeded in Summer 2016. The grass on the left is the sod the developer put down. The grass on the right is the neighbor's sod. Notice how smooth the soil is. The lawn installers rototilled in the compost shown in the second picture using the rototiller shown in the third picture on a Bobcat. They also had a crew who took great care to manually smooth the soil. Then it was hydroseeded.

Regarding top-dressing seed with a thin layer of soil, I disagree. The thin layer of soil keeps birds from eating the seed and provides a protective layer which holds the water I am putting down using the irrigation system. This is running at 8:30 am, 11:00 am, 1:30 pm and 4:00 pm for 5 minutes each for two zones. The last picture shows the patches with the top dressing. I used this method a few weeks ago in another section of this lawn and it worked well.

-Don

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