Lawn Problem: Annual Meadow Grass (AMG)

What is Annual Meadow Grass?

Annual Meadow Grass is commonly thought of as a weed grass as it has very distinguishing features which stand out against other cultivated grass species. It has a quick reproductive cycle as its tolerance to stress is not great. So in early summer you will likely see the plant “liming” when it is starting to run out of water and feed. As the name suggests it is an annual so it seeds and then those seeds germinate the following year. It is very common and can be seen growing almost anywhere, pavements, gutters, paths, etc.

How do I identify Annual Meadow Grass?

It’s not always easy to identify if you have Annual Meadow Grass (AMG) in your lawn but there are key times of year when you will know. AMG is a hungry and thirsty grass that likes compact soils. It will often go limey green before the rest of the grass when its stressed, giving the appearance of random shaped spots on the lawn. It is also likely to be seeding frequently, although this is not its defining feature. Turf experts usually either make it their life’s work to rid themselves of AMG or they live with it and manage it. The plant grows from a central point from which all stems can be traced and the flowers look like a sparse Christmas tree in shape. Rye grasses can look similar but tend to have flatter formations almost like they have been ironed flat.

How do I get rid of Annual Meadow Grass in my lawn?

As it is not possible to chemically kill AMG without killing the other grasses in your lawn, there are three approaches to dealing with AMG:

  • Kill the whole lawn and reseed it. This can be done effectively however there is no guarantee that AMG will not populate the new lawn. The main advantage of this approach is that when AMG starts to invade again (and it will), it can be hand weeded fairly quickly and easily. This approach is best used on heavily infested lawns.
  • Hide or camouflage the AMG. By keeping up a good feeding regime the AMG will not be distinguishable from other grasses, cutting regularly and scarifying in autumn (which it doesn’t like) will help keep a handle on the grass and limit its spread. Regular hand weeding by sliding a knife into the turf below the roots and teasing the grass out will reduce the population over time and make it more manageable.
  • Stressing the plant, using a Plant Growth Regulator (PGR) or reducing feed and water you can kill off the AMG. It is very shallow rooting and will die before the other grass species. The area can then be over seeded with desirable species. This can be tricky as you are trying to reduce input into the area to induce death of AMG then trying to get a new plant to grow. However this method of dealing with AMG has proved successful but is more tricky.

Key Points to remember

  • AMG cannot be killed in a lawn without killing other grass species.
  • Cultural methods of control provide the best answer to reducing the population.
  • Removing seed heads helps but it is not easy.
Thumbnail Photo by kazuend on Unsplash

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