Reed canary grass: where it grows, care and moths

Reed canary grass (Phalaris arundinacea) is a native bankside grass in the Netherlands. The grass grows 50 centimetres to 2 metres tall. Below ground, the plant keeps creeping outward on its rhizomes. In summer, narrow flower heads appear, white-green to pink. Plant reed canary grass in moist to wet soil, in full sun or partial shade.

Reed canary grass at a glance

Leaf

April to October

Flower

June to July

Fruit

no noticeable fruit

JanFebMarAprMayJunJulAugSepOctNovDec

How do you recognise reed canary grass?

Start with a leaf. The blade is flat, 0.6 to 2 centimetres wide, with a smooth edge. A broad, flat midrib runs down the middle. Young leaves come out rolled up.

Next, bend a leaf away from the stem. Where blade and stem meet sits a thin, papery tongue, called the ligule. This tongue can grow to more than 1 centimetre long and often frays.

Every stem ends in a narrow, cone-shaped flower head of 10 to 25 centimetres. Its spikelets sit together in dense little clusters. Below ground run thick rhizomes, mostly pink.

Common reed (Phragmites australis) grows on the same banks and looks similar from a distance. The ligule tells them apart: common reed has a ring of hairs there instead. Garden centres also sell 'Picta', a cultivar of reed canary grass with leaves striped white and green. The wild species has plain green leaves.

Where does reed canary grass grow best?

Reed canary grass grows in full sun and in partial shade. Around midsummer, a spot with three to six hours of direct sun is still fine for this grass. Its favourite ground is moist to wet and rich in nutrients. In the wild you find it at the water's edge, beside ditches, in reed beds and in rough grassland.

Two places in a garden lead to trouble:

• A border full of perennials. The rhizomes branch far underground. That way reed canary grass claims more and more of the border.
• A dry, sandy spot. Reed canary grass wants moist to wet soil and gets too little water there.

In autumn the leaves die off. Dead, straw-coloured stems then stand all winter, until you cut them down in spring.

JuneJanuaryThe same pond edge in June and in January. This is a generated image, not a photograph.

On a plan of your own plot you can see how much room a strip of reed canary grass gets along your pond. The app draws that plot to scale, with the nearby buildings on it.

Planting and caring for reed canary grass

Nurseries sell the wild species as a young plant in a small pot. Dutch shops label it rietgras. Dividing a clump works best from mid-April to midsummer.

Space the plants about 60 centimetres apart. The spread in the table is no guide here, because that figure describes a whole colony. On planting day, 60 centimetres looks bare. The rhizomes soon close that gap. Keep the soil wet through the first summer.

That spring cut sometimes falls in the breeding season. From March through July, many kinds of birds sit on their nests. So check between the old stems before you start cutting.

What goes wrong with reed canary grass?

The grass pops up all over the border. Those are the rhizomes. Between mid-April and midsummer, slice off the runners at the edge with a spade. Pull out the shoots already growing in the border too. Repeat this every year.

The leaves hang limp or wither. The soil is too dry. Water generously, or move the clump to the edge of the pond.

No flower heads appear. Mowing or cutting in June removes the flowering stems. Leave the clump alone in June and July.

Everything is brown in winter. That is normal. Cut the dead stems off in early spring.

Something is on the leaves. Pests and diseases rarely trouble reed canary grass. Usually nothing needs doing.

Which insects and birds use reed canary grass?

Reed canary grass is a host plant for moths. The caterpillar of the small clouded brindle (Apamea unanimis) feeds on various grasses, and reed canary grass is an important one among them. The adult moth flies from early May to early August.

The caterpillar of the double lobed (Apamea ophiogramma) eats reed canary grass and reed sweet-grass. This common moth also turns up in gardens.

The caterpillar of the southern wainscot (Mythimna straminea) feeds on common reed and reed canary grass as well. Among birds there is the bearded reedling (Panurus biarmicus), which lives in reed beds. In winter it eats the seed of common reed and reed canary grass.

Is reed canary grass poisonous or edible?

Reed canary grass is not known to be poisonous. No edible part of the plant is known either.