What is couch grass?
Couch grass (Elymus repens) is a perennial grass that spreads rapidly via networks of underground stems (rhizomes). It can infest borders and lawns.
How to identify couch grass?
Couch grass looks similar to other grasses, but instead of having a single clump of fibrous roots, it forms a dense underground network of roots and white rhizomes.
New shoots are produced each spring and autumn that quickly produce tufts of leaves and new rhizomes.
Couch grass damage
Couch grass spreads through borders and lawns, out-competing other plants for water and nutrients, and sometimes smothering them. The rhizomes grow in amongst the roots of other plants, making it difficult to remove them.
It is often spread easily from garden to garden as small sections of rhizomes become hidden in amongst the roots of other plants or in the soil.
Couch grass control
Couch grass is difficult to get rid of by hand, as plants can re-grow from any segments of roots left behind in the ground.
How to get rid of couch grass without using chemicals
- Where couch grass has not become too entangled with the roots of established plants, weed it out by hand with a hand fork. Take care to remove as much of the white rhizomes as possible.
- In heavily infested borders, it may be best to dig up all the plants and carefully remove all couch grass segments from the rootballs. Pot up the plants or plant them in a temporary bed, then dig over the infested bed, removing all couch grass rhizomes. Wait until all couch grass has been removed before replanting the bed.
- For lawns infested with couch grass, strip off all turf and dig out all couch grass rhizomes, then re-turf or re-seed the lawn.
How to get rid of couch grass using weedkiller
- In borders, use a systemic weedkiller containing glyphosate, like Roundup Ultra. The weedkiller is best applied in spring when the grass is in active growth. Glyphosate is a non-selective weedkiller and will kill any plant it comes into contact with, so protect all other plants with plastic sheeting. Repeat every six weeks until all the couch grass has been killed.
- For heavy infestation in borders, dig up all plants, remove all couch grass root segments from their rootballs and replant the plants in a temporary bed. Spray the infested bed with a systemic weedkiller like Roundup Ultra. Wait until all the couch grass has been completely killed before replanting the bed.
- There are no selective lawn weedkillers that will get rid of couch grass in lawns without killing the other grass, so the only solution is to replace the lawn. Spray the affected area with a systemic weedkiller containing glyphosate, such as Roundup Ultra, which will kill all the grass, including the couch grass. Once all the grass has died, dig over and re-turf or re-sow the area.
- Always follow the manufacturer’s instructions when using weedkiller.
How to prevent couch grass?
Couch grass is often brought into a garden as segments of rhizome in the rootballs of other plants.
- Before planting, check the rootballs of plants that have been moved from other areas and remove any couch grass rhizomes.
- Dig up any couch grass plants as soon as they emerge to stop them spreading.