Glyceria maxima - Reed Sweet-Grass, Native Pond Marginal Plant

Glyceria maxima, known as reed sweet-grass, is a tall UK native grass of pond margins and shallow water. It has broad, strap-shaped green leaves, tinged pink in spring, and from June to August carries open, branched, purplish-green flower heads.

Reed sweet-grass at a glance

Botanical name	Glyceria maxima
Common name	Reed sweet-grass, reed meadow-grass
Plant type	Tall, spreading grass; dies back in winter
Height and spread	Usually about 1 m or more (sources range from 0.5 to 1.8 m); spreads 1.5 m or more
Flowers	Purplish-green, in open branched heads, June to August
Position	Full sun
Soil	Wet, poorly drained soil or shallow water
Pond depth	0–15 cm of water (up to 30 cm)
Hardiness	RHS H6 – hardy in a very cold winter (-20 to -15°C)
Native to	UK (native)

Is reed sweet-grass suitable for a garden pond?

Only a large one. The RHS says it can spread almost indefinitely and has the potential to become a nuisance, and a UK nursery says it is not for the small pond. Grow it beside large ponds, lakes and wetlands, or in a solid basket.

Is it good for wildlife?

Yes. The stems give cover and let insects climb out of the water to emerge, the seed heads feed birds in winter, and the roots help to stabilise banks.

Is it poisonous?

Yes, to livestock. Fresh young growth contains cyanide-forming compounds and has killed cattle. Do not plant it where grazing animals can reach it.

How to plant and care for it

Plant from spring to late summer. Divide it every few years, and remove the seed heads to stop it self-seeding.

Which size should I buy?

Bare-root plants (7 cm, 9 cm, 1 litre and 3 litre) arrive without a pot or compost and are the most economical way to plant a group. Potted plants (9 cm, 1 litre and 3 litre) arrive growing in our peat-free compost and give a faster display. The 2x Pot & Compost option is two plants supplied with pots and compost.