Giant miscanthus

Miscanthus × giganteus

In other languages: Olifantsgras (Nederlands) · Herbe à éléphant (Français)

Giant miscanthus is a huge grass that arose from a natural cross between two Asian species, Miscanthus sinensis and Miscanthus sacchariflorus. It was brought from Japan to Europe in the 1930s. Every spring its rhizomes send up sturdy, bamboo-like stems that reach 3 m or more in a single season, with long, arching leaves that have a white midrib. In our climate it rarely flowers, and it sets no viable seed: it is sterile. Gardeners use it as a fast-growing summer screen, as a backdrop for large borders and as a focal point beside a pond.

Caution: It needs plenty of room: it grows 3 m tall and a little wider every year, so do not plant it too close to paths, walls or small plants. The leaf edges are sharp: wear gloves when cutting back and do not plant it where small children play.

Updated on 9 October 2026

Light
Full sun
warm and bright
Moisture
Normal to wet
must not dry out
Legal basis
Sand, loam or clay
any pH
Hardiness
Fully hardy
down to -25 °C
Size
3 m
tall, 1.5 m wide

Key facts
Pruning months	March
Height	3 m
Native to Belgium	No, planted
Poisonous to people and pets	Not known to be poisonous

Identify

Giant miscanthus: how do you recognise it?

Habit: Dense, upright clump 3 m tall and 1–1.5 m wide, slowly getting wider.
Stems: Finger-thick, sturdy and bamboo-like; they usually stay upright in winter.
Leaves: Long, narrow and arching, green with a white midrib; yellow-brown to straw-coloured in autumn.
Flowering: Rarely or never flowers here; only after a long, warm summer are there sometimes late, silvery plumes without viable seed.
Roots: Thick rhizomes; the clump gets a little wider every year, but does not run far like bamboo.

Plants: March–May · Pruning: March

In your garden

Why grow it?

Grows back every year into a 3 m green screen: summer privacy without a hedge.
Does not self-seed, because it is sterile.
Leaves that rustle beautifully in the wind, and a sturdy, straw-coloured outline in winter.
Little work: one cut a year.
The shredded stems make a fine mulch for the rest of the garden.

Giant miscanthus: where does it grow best?

Full sun; in shade it stays shorter and floppier.
Any fertile soil: sand, loam or clay, acid to chalky.
Moist to damp; on moist soil, including a pond edge, it grows tallest. On dry sandy soil, water in summer.
An open spot, but not fully exposed to the wind: autumn gales can flatten the tall stems.
Plant 1–1.5 m apart and at least 1 m from paths, walls and small plants; 1 m apart for a screen.

Light: Sun
Soil type: Sand, loam or clay
Acidity: Not fussy
Moisture: Normal or wet
Size: 3 m tall, 1.5 m wide
Hardiness: Hardy (to -25 °C)

Goes well with

Hemp agrimony: Large pink flower heads in late summer, also on moist soil.
Perennial sunflower: Yellow flowers into October, just as tall and sturdy.
Purple loosestrife: Pink spikes on moist soil and by the pond.
Coneflower: Pink or yellow flowers at the front, low against the tall grass.

Maintenance

Giant miscanthus: when and how to plant it?

Plant in March–May.

Plant in March–May as the soil warms up: that is when it roots fastest.
Dig a generous hole and mix in compost or well-rotted manure.
Set the plant at the same depth as in the pot, or lay rhizome pieces 5–10 cm deep.
Leave 1–1.5 m between plants; 1 m is enough for a screen.
Water thoroughly straight away and regularly in dry spells during the first year.
Mulch with compost or last year’s shredded stems.

Care

Water: Plenty of water in dry spells during the first year. Later only in long droughts, especially on sandy soil.
Feeding: A little compost in April; nothing more is needed.
Patience: It starts into growth late, often in May. In the first year it stays shorter; from the second or third year it reaches full height.
Rhizomes: The clump gets wider every year. Chop off the edge in spring if it takes up too much room.
Mulching: A layer of compost or shredded stems in spring keeps the soil moist.

Tip: In March, tie the stems together with string first and then cut them in one go: you get a neat bundle to carry straight to the shredder.

Giant miscanthus: when to prune it?

Pruning months: March.

When: Cut all stems down in March, before the new shoots appear.

How:

Cut or saw all stems down to 10–15 cm above the ground; hedge shears or a pruning saw work best.
Tie the stems together with string first: they will not fall everywhere and are easy to carry away.
Shred them for mulch or add them to the compost heap.
Do not wait too long, or you will cut the young shoots as well.

Caution: Wear gloves and long sleeves: the leaf edges are rough and sharp and can cause small cuts.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Division: In April, chop or saw a piece of rhizome with a few buds from the edge and plant it straight away. Old clumps are very tough: use a sharp spade or a saw.
Seed: Not possible: giant miscanthus is sterile and sets no viable seed.

Giant miscanthus: how does it get through the winter?

Hardy to −25 °C.

Hardy to about −25 °C; established plants need no protection in Belgium.
Young plants in their first winter: a layer of mulch over the base protects the rhizomes from hard frost.
Leave the stems standing all winter: they look lovely with frost and protect the base.
It is not well suited to pots: it grows too big and dries out quickly.

Diseases and pests

Late start: No green until May: do not panic, this is normal for this warmth-loving grass.
Collapsing stems: After autumn gales or in too much shade. Choose a sunny, slightly sheltered spot and simply cut off fallen stems.
Bare centre: Old clumps die out in the middle. In April, dig out the dead centre and fill with compost, or divide the clump.
Too wide: The clump slowly creeps outwards. Chop off the edge every spring.

Through the year

January: Leave the stems as a winter outline.
March: Cut all stems down to 10–15 cm. Plant.
April: Plant and divide. Add compost.
May: New shoots appear. Plant. Water in dry spells.
June: Rapid growth. Water in dry spells.
July: The screen closes. Water in long dry spells.
August: Full height, 3 m or more.
October: The leaves turn yellow-brown.
November: Leave the stems standing.
December: Winter stems with frost.

You and this species

Did you know?

It is triploid: it has three sets of chromosomes and therefore cannot form viable seed. That is why it never self-seeds.
In Europe it is also grown in fields as an energy crop: the dry stems are harvested as biomass.
A Danish nurseryman brought it from Japan to Europe in the 1930s; almost all plants here have been propagated vegetatively from that material.

Garden plants · All species