Which? Gardening Magazine
Expert advice through the seasons so you know what to do and when. £4.99 a month, cancel anytime.
Sign up nowIn this article
Couch grass (Elymus repens) is a stealthy invader that creeps underground through tough, wiry rhizomes and can spread several metres in a season. It is also known as twitch grass. It can be tricky to get rid of because the rhizomes insinuate themselves between the roots and stems of established plants and into nooks and crannies at the bases of hedges, fences and walls. The rhizomes have sharp tips that can pierce other plants, plastic sheeting and even pond liners.
Expert advice through the seasons so you know what to do and when. £4.99 a month, cancel anytime.
Sign up nowIt can be tricky to get rid of because the rhizomes insinuate themselves between the roots and stems of established plants and into nooks and crannies at the bases of hedges, fences and walls. The rhizomes have sharp tips that can pierce other plants, plastic sheeting and even pond liners.
When Which? Gardening magazine trialled different methods for controlling couch grass, we found that glyphosate sprays wins hands down. Most of the couch grass was killed after one treatment of Roundup. The glyphosate-sprayed plots remained largely clear of couch grass the following spring, too.
The main concern is that glyphosate can cause cancer. A second concern is the negative effect glyphosate use has on bee health. However it is legal to use.
Make more of your garden - get our free Gardening newsletter for top tips from our experts
For organic gardeners the best chemical-free method for controlling couch grass is digging it out by the roots. In our trial this was far better for reducing their number than pulling them up and a bit better than hoeing. Either way, the beds had more couch grass than glyphosate-treated ones the following spring.
Glyphosate gel reduces the amount of couch grass over the summer and the following spring, but was slower than sprays to work.
Triclopyr, the selective weedkiller in Vitax SBK specifically targets broad-leaved weeds and is completely ineffective on couch grass.
Burning couch grass has little effect on controlling the number of weeds. It becomes unwise to try burning the couch as the grass dries out.