Giant Chinese silver grass

Family

Poaceae

Habit

perennial

Height

3 m

Spread

3.5 m

Growth

fast

Lifespan

20 years

Productive years

3–15 years

Yield in cultivation

up to 20 t/ha

Energy yield

4000 kcal per m² a year

Hardiness

zone 4–9

Shade tolerance

light shade

Soil

Sand, Silt, Loam, Clay

Soil moisture

semi-dry – very wet

pH

5.5 – 7.5

Synonyms

Miscanthus

Times apply to the northern hemisphere in a temperate climate and shift with altitude and cultivar.

Edible: Giant miscanthus is not a food plant and is not used as one. For the parent species Miscanthus sinensis there are reports that the still-unripe flower heads are edible — for the hybrid itself no such records exist, and since it flowers only rarely and irregularly the question is academic anyway. Its cultivation is aimed entirely at stem biomass: fuel, animal bedding, insulation and fibre materials. Anyone looking for an edible giant grass is better served by sugar cane or by the bamboos with edible shoots.

Medicinal: The juice of young stems is utilized for dispersing toxins, dissolving blood clots, diverting extravasated blood, and alleviating inflammation. The plant has diuretic and cooling properties.

Other uses: Carbon Farming Solutions – Industrial Crops: Biomass (crops not grown for the food industry. Industrial crops provide resources in three main categories: materials, chemicals, and energy. Traditional materials include timber and straw, paper and cardboard, as well as textiles). Only a few perennial industrial crops have been properly domesticated. Those that have show significantly higher yields. Miscanthus x giganteus is partially domesticated. An excellent biomass producer in temperate climates, requiring very little nitrogen fertilizer. Most of the giant miscanthus is used for biofuel but could also serve as feedstock for a range of bio-based materials. Livestock feed: Bank. A potentially good candidate for contour hedgerows in agroforestry. An excellent windbreak. A popular ornamental plant – Outstanding autumn color that remains attractive in winter.

Site: The rule of thumb is a comparison with maize — a good maize site is a good miscanthus site. Ideal are deep, humus-rich, freely rootable loams with high nutrient storage and 500 to 600 millimetres of rain during the growing season; light sandy loams work too, where rainfall distribution between June and September decides the yield. Cold, waterlogged and poorly aerated soils are out, as are elevations above 700 metres. On marginal sites growers often try it tentatively and are positively surprised, because the underground rhizome all but rules out total failure. Since the hybrid is sterile it does not self-seed and spreads only slowly by rhizome — unlike Chinese silver grass it stays controllable. Height needs thought: from the third year the stand is three to four metres tall and casts a long shadow from late summer, darkening neighbouring beds and paths. That same height is what makes it valuable as a buffer strip: five to ten metres of miscanthus between a conventionally farmed neighbouring field and your own garden, a watercourse or a forest garden slows both spray drift and run-off; well-developed riparian buffer strips are credited with retaining up to ninety per cent of incoming pesticides and nutrients, at a minimum width of five metres and up to twenty for critical substances. Care: The first two years are decided by weed control, because as a C4 plant miscanthus needs mean temperatures of at least eight degrees and starts late in spring — by which time the surrounding vegetation has a head start. Late frosts can damage young shoots. From the third year the stand closes, suppresses weeds itself and needs practically no attention; feeding is unnecessary or minimal, because the plant withdraws nutrients into the rhizome before harvest. Irrigation pays only on very light soils, since too much water at the roots suits it badly. Harvest from January to March, once the culms have dried through and the nutrients are stored, and in any case before regrowth in April — cutting later damages the new shoots and weakens the stand. The chopped material serves as mulch, bedding or fuel. A planting stands twenty years and more; to clear the ground again the rhizomes must be milled out and the area worked over for a season.

Giant miscanthus is a triploid hybrid with 57 chromosomes and therefore sterile — it sets no viable seed. Sowing is out of the question; propagation is entirely vegetative, by dividing the rhizomes. Planting runs from March to May once the soil has warmed, at about one to one and a half rhizome pieces per square metre; each piece needs at least two or three buds and goes some ten centimetres deep. In the first and second years weed control decides whether the stand succeeds, because the plant starts late in spring. From the third year the stand closes and looks after itself; a planting lasts twenty years and more. Commercial growers also work with micropropagation.

Habitat: Birds use the stems as winter quarters. In Central Europe a great number of small creatures such as spiders and beetles use giant miscanthus as overwintering quarters. In farmed landscapes tidied up over winter, roe deer and wild boar use miscanthus stands as a refuge. Insects find shelter in the dense clumps.

Special: Sterile triploid (57 chromosomes) -> no viable seed, does not self-sow (unlike M. sinensis); C4 grass, minimum temperature 8°C, starts late+poor competitor in spring; clump stays within about 1m², no runners; up to 4m growth in one season; harvest Jan-March after nutrients withdraw into the rhizome, before regrowth in April; yield 10-20t dry matter/ha, 25-30t irrigated; stand lasts 20+years;

No natural range — giant miscanthus is a cultivated plant. It arose in Japan as a natural cross between Chinese silver grass (Miscanthus sinensis) and Amur silver grass (Miscanthus sacchariflorus), whose combined range covers Japan, China and Korea. The entire European stock goes back to a single clonal line that reached Central Europe via Denmark around 1935, at first as an ornamental grass. Since the 1980s the plant has been grown as an energy and fibre crop, with centres in Germany, Austria, Britain and increasingly in Eastern Europe and the American Midwest. Because it is sterile, it stays wherever it was planted.

The parent species of giant miscanthus occupy moist meadows, riverbanks and slopes in East Asia, from the lowlands into the hills. The hybrid itself occurs nowhere in the wild, but its requirements follow that ancestry: it is warmth-loving and runs C4 photosynthesis, for which it needs at least eight degrees to get going at all — so it stands still in early spring and competes poorly with weeds. It grows best on deep, humus-rich loams with 500 to 600 millimetres of rain during the growing season. It roots shallowly, forms a dense mat of rhizomes and so protects the soil against erosion, but reacts badly to prolonged summer drought.