Types of invasive grass in lawns: What to look for

A good-looking lawn adds kerb appeal to a property and, whether at the front or back of your house, they tend to be very visible. Whether you’re outside admiring your lawn from close up or glancing out of the window at it from indoors, they can have a huge impact on the appearance of your house. In this Cosy Home gardening guide, we reveal some of the most common types of invasive grasses and grassy weeds that can occur in lawns and damage your healthy grass, so that you know what to look for and what invasive plants you need to get rid of to keep your lawn in tip-top shape!  

Invasive grasses

Just like flowerbeds, lawns are prone to weeds which can spoil their appearance and affect a healthy lawn. In addition to dandelions and other flowering plants, you may notice patches of invasive grass appearing on your lawn – also known as coarse grass or wild grass, these are unwanted grasses that seem to magically appear and multiply.

While a few of these grasses can add a bit of interest in your lawn, they’re quick to spread and can quickly take over the whole area, starving the ‘good grasses’ of water, daylight and nutrients. That’s why they’re called invasive grasses or invasive weeds, as they are not normal forms of regular grass or turf grass and can cause your healthy manicured lawn to deteriorate as the new plants invade. If these types of weeds take over on your lawn, you may be left with small patches of bald areas, as they crowd out healthy grasses. 

It’s surprising just how many types of invasive grasses there are and how easily they can make their way onto your lawn due to airborne seeds. Lots of these invasive species are known by several names, so we’ve tried to include the alternative names too to help you identify them better. 

Poa annua

Poa annua (also known as annual meadow grass and annual bluegrass) is one of the worst offenders in terms of lawn weeds. This annual grass is low growing and has feathery seed heads. Despite the name, there are some perennial varieties so it can be an issue all year round. The grass seeds a lot between early spring to autumn and the unwanted weeds can easily disperse more seeds into the affected area. 

Yorkshire Fog (Holcus lanatus)

Yorkshire Fog (also known as crab grass, fog grass, meadow soft grass, or velvet grass in North America) is a common form of invasive grass or perennial weed. This grass has broad, soft, slightly hairy pale green leaves. Its flower heads can be purple to red in colour and when it turns to seed, they are grey to pink in colour. Large areas of this perennial grass will appear as patches of paler green in your lawn.

Couch grass (Elymus repens)

Couch grass (also known as twitch grass) is a complete pain if it’s invaded your garden! It has thin, wiry leaves and spreads underground, so it’s very difficult to eradicate. This grass type is commonly found between spring and autumn and has a very strong root system. In fact, just pulling up the shoots won’t have much effect on its growth habit. With small areas you may be able to dig up the roots, but larger areas will only really respond to proper weed control using weed killers.

Green foxtail (Setaria viridis)

Green foxtail is a form of annual grass that typically appears in early summer, with flowering in late summer and early fall. If you’ve ever seen this weed in seed you’ll know it immediately – the seed heads look exactly like miniature fox’s brushes. It grows fast, and can quickly take over your lawn if you let it. It can also be an issue if you have pets, as the awns (bristle-like projections on the seed head) are very sharp and can work their way under pets’ skin and cause sores. 

Rough stalked meadow grass (Poa trivialis)

Rough stalked meadow grass is fairly common in the UK and Europe and can be very invasive. It’s commonly used for hay and stock feeding, so if your garden backs onto fields it may cause a problem. It’s a rough, broad, dark green grass which grows in distinctive circular clumps, with leaves towards the bottom and tufts at the top, so it’s relatively easy to spot. The best course of action to get rid of rough stalked meadow grass is just to dig up the clumps as you see them.

Nutsedge

Nutsedge, also know as nutgrass and sedge grass, is strictly speaking not a true grass but is often mistaken for one because of its triangular leaves and the fact that it appears persistently in turfgrass. Nutsedge grows prolifically in warm weather (for example, it’s commonly found throughout the year in Florida), but an outbreak of this weed often starts in moist environments and shady areas whether other plants don’t thrive – and it spreads like wildfire! Once it has become established, it’s a drought-tolerant weed and its root systems go deep down. The best way to get rid of Nutsedge is to dig it up at the base of the plant, including all the roots, or to use weedkiller or selective herbicides if it’s away from other plants. 

Tall fescue

Tall fescue is another type of perennial invasive grass that can easily stray in from nearby fields, where it’s often grown for hay and pasture. It’s too large and tall for domestic lawns, but the tall grass can look nice  alongside the rest of your lawn if you have an area of wildflowers. The grass flowers during the summer months, before turning to seed. If you don’t want this grass mingling on your lawn, try spraying it with herbicide treatment to remove it. 

Endnote

Hopefully you’re now better clued up on the common forms of pesky invasive grasses than can infiltrate your well groomed lawn. If you do face any of these culprits, it’s best to act quickly and take action before they become too established.

All images (c) Pixabay

By Sara Walker.