Dealing with couch grass

Couch grass is a common problem in cultivated garden areas, owing to its vigorous, spreading underground stems. Couch grass is easily spread by cultivation because it regrows from even tiny pieces of root left in the soil, but is straightforward to restrict when identified at an early stage. It's worth bearing in mind that couch grass does have benefits for wildlife: the leaves are a foodplant for the caterpillars of many types of butterflies and moths, and clumps provide shelter for other invertebrates, such as beetles. Couch grass could therefore be allowed to grow in garden lawns or wilder areas, where it can be kept from spreading into beds and borders.

What is couch grass?

Couch grass, also known as twitch or scutch, is a perennial grass species that is native to the UK, and which grows widely in farmland, road verges, and uncultivated land, as well as in gardens. The botanical name of couch grass is Elymus repens.

Identifying couch grass

Above ground, couch grass can be confused with other grasses, with its flat green blades that can reach 40cm long. But digging up the plant will reveal its spreading underground stems (rhizomes). These rhizomes are a pale cream or white colour and have a sharp growing point. Knowing what couch grass looks like, when compared to annual ‘weed’ grasses and lawn grasses, is important, so that you can spot and eradicate it at an early stage. Thin, yellow-green flower spikes appear in mid to late summer and can reach up to 120cm high.

Does couch grass cause problems?

Couch grass is only a problem in cultivated areas like garden borders and vegetable beds. Here, not only does couch grass spread rapidly to form dense mats of underground stems, but the major problem occurs when it grows through the root systems of garden plants, when it becomes very difficult to eradicate. It competes with plants for water and nutrients and reduces crop yields in vegetable beds. Gardeners battling with it often ask can you ever get rid of couch grass. The answer is yes, though it often takes a few goes to eradicate it completely. In a lawn, couch grass is less of a problem, because regular mowing keeps its growth in check. However, be aware that its underground stems are likely to spread into adjacent beds and borders.

Couch grass and the law

There are no laws relating to couch grass. However, if you have couch grass growing where it may spread to neighbouring plots, it is considerate to keep it in check.

How to prevent couch grass

Tackling couch grass at an early stage will save a lot of hard work later. Try and prevent it becoming established as it will be harder to eradicate. Watch out for couch grass spreading into your garden from neighbouring plots or wild land. If this is the case, dig a trench in the ground along your boundary, at least 30cm deep, and line with a tough material such as special root barrier membrane (the sharp tips of couch grass roots can pierce plastic or thin membrane).

Help prevent couch grass spreading from a lawn into an adjacent flower bed by installing a lawn edging strip. While this is unlikely to stop the spread of all growth, couch grass is shallow rooted, so it will certainly work to some extent. The seeds produced by couch grass are relatively few and only a small proportion are likely to germinate, but it’s still a wise precaution to remove and bin any that appear.

How to control couch grass

Dig out all the roots and underground stems of this grass, especially at the edge of infested lawns. It's best to use a garden fork to carefully lift out networks of the rhizomes. A spade will cut them up and make it harder to find all the pieces. Where couch grass is growing in among long-lived plants in borders, it will be necessary to lift plants while dormant and tease out the weed from the rootballs. While systemic weedkiller can be used to control couch grass in areas apart from lawns, this is best considered as a last resort due to potential environmental impact.

How to remove couch grass

Avoid putting couch grass growth in your garden compost bin where it will continue to grow. Instead, dispose of it in your garden waste collection, or take it to your local council waste disposal site.

Frequently asked questions

What is another name for couch grass?
The botanical name of couch grass is Elymus repens. Other common names for couch grass are twitch grass, scutch, wickens, and grandmother grass.

How to prevent couch grass?
Dig up couch grass as soon as growth is seen. Prevent couch grass spreading in from outside by installing underground barriers or frequently digging up invading growth. Where couch grass is growing in lawns, regularly cultivate by cutting a fresh edge to the lawn using an edging iron and then turning over adjacent border soil using a fork to remove any couch grass roots which are spreading into borders. If bringing in topsoil or manure from outside, ensure it is free of perennial weed roots.