Weed grasses are a common pest in lawns and are a particular issue in lawns that haven’t been reseeded in a few years. At first, you may notice certain areas of your lawn sporting thicker green grass and might think you’re onto a winner, however this ‘grass’ will quickly become unaesthetically pleasing and can really ruin the look of a pristine lawn.
Fortunately, there are a few ways to spot and remove weed grasses before they become a major pain.
Why do weed grasses appear?
Weed grasses can be introduced to your lawn, without you knowing, in a variety of ways. On most occasions weed grasses are not the fault of the lawn owner, but more of an unfortunate reality of being one! Weed grasses can appear in your lawn after seeds have been dropped by birds or have been simply laying dormant in the soil until they have had good conditions to grow. Weed grasses are more likely to appear in compacted, drought-stricken lawns that are also excessively mown. These conditions put the lawn and current grass under stress, allowing for the weed grasses to thrive.
What type of weed grasses are there?
The three most common weed grasses you will come across in any UK lawn are Poa Annua also known as Annual Meadow Grass, Couch Grass nicknamed Yorkshire Fog and Rough Stalked Meadow Grass. Treatments for removal of these are fairly similar and are covered in our ‘Control’ section.
Why is it a problem?
General unsightliness isn’t the only downside to the presence of weed grasses in your lawn. Lawn mixes such as our own are often designed with different needs in mind, like drought resistance, wear and tear resistance, longevity etc. With weed grasses present this can disrupt the balance in your lawn and leave areas more susceptible to the above problems.
The actual spread of weed grasses is the biggest issue as their roots can become entangled in shrubs and fruit bushes, making them difficult to remove and allowing them to hop from garden to garden without much difficulty.
As with most lawn related problems, preventing it is much easier than trying to remove it. A healthy lawn is a great barrier to weed grasses as thick, well established grass roots can help prevent their spread. Maintaining a healthy lawn with regular practices such as scarifying, aerating and most importantly, feeding can really improve grass root strength and help the lawn fight off all types of weeds, not just unwanted grasses.
Re-seeding is also an important practice in lawns. It is not unusual for some grass to die in flooding or drought conditions, but this does open pockets for weed grasses to grow in. By reseeding, you can ensure that the majority of your lawn is made up of grass, and not grass and a layer of thatch. Lots of UK lawns contain species such as perennial ryegrass and fescue which are considerably long lasting grasses - but overseeding every few years can really help the composition of your lawn and make sure no alien species sneak into your lawn undetected.
If you spot weed grasses early enough in your lawn, they should begin to die off with closer mowing by using the lowest setting on your lawn mower. As they are broad leafed, they won’t tolerate this close mowing and will suffer from it.
If they do not suffer from this method, then it’ll be time to get your hands dirty. If possible, you should try to remove weed grasses by hand, this may not be practical especially if the weed grass has spread, but if you catch it early enough, there is a good chance this will work just fine for certain isolated cases. If you don’t want to use your hand, you can use a blade to cut vertically at the roots. Remove the clumps, prepare the soil from scratch and replace with seed.
If the ‘hands on’ method fails, then this leaves the option of a chemical approach. Like with lots of weeds, a glyphosate solution (Roundup) can be applied to the area to kill off weed grasses. These products aren’t selective so it is important to apply them precisely to areas where weed grasses are present as this will avoid any damage to your actual grass.
The main thing to remember with any weed grass is that it’s important to identify, prevent and control infestations as quickly and effectively as possible to stop it becoming a more prominent addition to your garden.
If weed grasses have overtaken your lawn, it is better to consider removing the turf entirely and starting from scratch.