Common couch

How to recognise it

Habit

Grass of 30–100 cm that forms loose, extensive patches from rhizomes rather than tussocks.

Leaf

Dull green to bluish green, flat, 3–10 mm wide, often with scattered hairs on the upper side. At the base of the leaf blade are two small auricles that clasp the stem; the ligule is very short.

Flower

Straight, narrow spike of 5–15 cm, from June to August. The spikelets sit in two rows with their broad side against the stem; each spikelet has two glumes and sometimes short awns.

Fruit/Seed

Elongated grains, ripe in August–September.

Roots

Long, white, branching rhizomes with nodes and a hard, sharp tip, mostly in the top 10–20 cm of soil. Any piece with a node can grow into a new plant.

Confusion with

Perennial rye-grass has spikelets set edge-on to the stem, only one glume, glossy leaves and no rhizomes. Bearded couch forms tussocks without rhizomes, has long awns and grows in woodland. On the coast grows sea couch, with stiff, bluish-grey leaves.

Flowering: June–August · Pruning: June and September

Why grow it?

• Foodplant for the caterpillars of, among others, the speckled wood and the ringlet, and of many grass-feeding moths.
• Its network of rhizomes binds loose soil on banks, dykes and dunes.
• A pioneer that quickly covers bare, disturbed ground and so limits erosion.
• In a verge or wild corner its tall growth shelters grasshoppers, spiders and small mammals.
• In times of scarcity, the rhizomes were once dried and ground into flour.

Common couch: where does it grow best?

• In the wild: arable fields and margins, road verges, dykes, riverbanks, dunes, rough ground and waste land.
• Sun to partial shade; in deep shade it stays weak.
• Almost any soil, from dry sand to moist clay, preferably fertile and disturbed.
• In the garden it belongs only in a wild corner, a hedge bank or a verge, well away from the vegetable garden, borders and lawn.

Goes well with

• False oat-grass: Together a tall, rough grassland for grasshoppers and caterpillars.
• Wild carrot: White umbels above the grass; food for hoverflies.
• Tansy: Yellow buttons in late summer; holds its own among couch on rich soil.
• Common nettle: Foodplant for the peacock and small tortoiseshell in the same wild corner.
• Common comfrey: Bells for bumblebees in May–July; also grows in a rich, wild corner.

Common couch: when and how to plant it?

1. Never plant couch in or next to a vegetable garden, border or lawn: it runs under edging and paths.
2. Usually it arrives by itself, with soil, compost or plants from other gardens, so you rarely need to plant it.
3. To green a wild corner or bank, simply let the couch that is already there grow, or sow a mix of native grasses.
4. Border the spot with a path that you keep mown short: frequent mowing holds it back.
5. Never take soil containing bits of rhizome to another garden, and never dig up plants in the wild.

Care

Watering

Not needed, even in dry summers.

Feeding

Never: on rich soil it grows even more vigorously.

Mowing

Mow a wild corner or verge once or twice a year and remove the cuttings. In a lawn, regular mowing weakens it a lot.

Weeding

In the vegetable garden and borders: loosen the soil with a fork and pull the rhizomes out whole. Repeat every time new shoots appear; this exhausts the rhizomes.

Smothering

You can cover a weedy patch of vegetable garden for a whole season with cardboard and a thick mulch, or with light-proof sheeting. Without light most of it dies.

Composting

Do not put fresh rhizomes straight on the compost heap: first let them dry out in the sun or drown them for a few weeks in a bucket of water, or put them in the green waste bin.

Tip: Never rotavate a patch full of couch: fork the rhizomes out whole and remove every new shoot as soon as you see it. That way the plant is exhausted within a season or two.

Pruning and mowing

Pruning months: June and September.

When: In a wild corner or verge, in late June and in September.

How:

• Mow at 5–10 cm with a scythe or a bar mower.
• Mow before the seed ripens if you do not want it to self-seed.
• Remove the cuttings so that the soil becomes poorer and other plants get a chance.
• Leave part standing each time as shelter for insects, also over winter.

Caution: Never rotavate ground with couch in it: the rotavator chops the rhizomes into pieces, and each piece grows into a new plant.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Rhizomes

This is how it mainly spreads: the rhizomes grow a good way further each year, also under paths and edging. Any piece with a node can sprout.

Seed

Ripens in August–September, drops around the plant and travels with cuttings, hay and soil.

Soil and compost

Bits of rhizome travel with soil, compost and the root balls of plants from other gardens. Check plants you are given.

Common couch: how does it get through the winter?

Hardy to −30 °C.

• Most leaves die back and turn straw yellow; in mild winters green shoots keep growing.
• The rhizomes overwinter in the soil and sprout straight away in early spring.
• Fully hardy, to about −30 °C.
• Late February–March is a good time to fork out rhizomes in the vegetable garden: the soil is bare and you can see them well.

Diseases and pests

• Weed: In vegetable gardens and borders it chokes other plants. Fork out the rhizomes, pull new shoots at once and keep the soil covered.
• Piercing: The sharp tips of the rhizomes grow right through potatoes, the roots of perennials and loose soil. Lift infested perennials, rinse the root ball and pick out the rhizomes before replanting.
• Under edging: It creeps under paths, paving and border edging. A mown strip or deep edging helps; check the edges every spring.
• Ergot: A fungus that forms black, horn-shaped grains in the spike. They are poisonous to grazing livestock; mow a verge or meadow rich in couch before the seed ripens.

Through the year

• February: Fork out rhizomes in the vegetable garden as soon as the soil is workable.
• March: New shoots. Check the edges of borders.
• April: Pull every new shoot in the vegetable garden at once.
• June: Flowering starts. Mow the wild corner in late June and remove the cuttings.
• July: In flower. Keep weeding in the vegetable garden.
• August: End of flowering; seed ripens.
• September: Second cut in the wild corner. Cover bare vegetable beds with mulch or a green manure.
• November: Leaves turn straw-coloured; leave them in the wild corner.

Did you know?

• The Dutch name kweek is related to kwiek, ‘lively’, and to the English quick, ‘alive’; the name couch goes back to the same root. A grass that is almost impossible to kill.
• The French name chiendent literally means ‘dog’s tooth’.
• In times of scarcity the rhizomes were once dried and ground into flour, and they were also fed to livestock.