726 Miscanthus floridulusCommon Names: giant miscanthus, giant eulalia grass, Japanese silver grass, Amur silver grass Family: Poaceae (grass Family)
Giant miscanthus is a huge and robust ornamental grass that can stand as tall as 15' and spread out more than 8 ft (2.4 m) across. The leaves are flat, but slightly folded, about an inch and a half wide, and 3 ft (0.9 m) long. They are deep green with a white midvein. The leaves arch gracefully outward from stout reedlike culms (stems) up to 2 in (5 cm) in diameter that grow upright from a central clump. The overall appearance is like a giant green water fountain. In late summer or autumn, giant miscanthus produces 18-20 in (46-51 cm) silvery silky plumes that are held high above the leaves on strong stems. The plumes stay silvery-white, but the foliage turns beige and russet in early winter. The leaves eventually drop off in winter, leaving just the vertical stems. Although it is technically a clump grass and not a turf-forming grass, giant miscanthus spreads and enlarges slowly with short underground rhizomes.
Look for the name, "Giganteus" if you want this grass. It may be listed as a variety of Miscanthus sinensis, M. sacchariflorus, M. japonicus, or simply as Miscanthus 'Giganteus'.
Giant miscanthus, Miscanthus floridulus, is native to Japan, the Ryukyu Islands, Taiwan, and other islands in that part of the Pacific. It has become an invasive pest in Guam and other Pacific islands outside it native range.
CultureGiant miscanthus flowers late in the season and may not bloom at all in northern latitudes. Cut dead stems back to the ground before new growth begins. Light: Giant miscanthus does best in full sun. It is likely to stretch for the sun and wind up falling over if planted in too much shade. Moisture: Giant miscanthus needs lots of water during its growing season, but likes it dry in the winter. It tolerates fairly moist soils, but does best in well-drained soils with frequent watering. Hardiness: USDA Zones 5 - 9. Giant miscanthus flowers best following long, hot summers, and it may not flower at all in zones 5-7. Propagation: Propagate giant miscanthus by dividing the root crown. This can be done with a back hoe or steam shovel if a standard garden spade seems inadequate.
Use giant miscanthus as a stand-alone specimen or plant several in a line to form a screen - no, make that a barricade! Use it to anchor a mixed border, but you probably will want to keep it in the background. Giant miscanthus tolerates fairly wet soils and often is planted at waterside. The persistent stems and long-stalked flowers provide vertical structure and form through the winter. Giant miscanthus tolerates salty and coastal conditions, and can be used in seaside gardens, but withered, winter foliage is likely to be blown off in strong winds. Lower leaves tend to wither and drop off late in the season anyway, leaving a bare zone that may beg for something planted in front. The flowerheads are used in floral arrangements, both fresh and dried plumes persisting indefinitely.
Definitely not for the small garden, giant miscanthus is an imposing and dominating plant, an imperial grass that plays second fiddle to no other. Use it where you want it to be seen! And, know that it will continue to enlarge (slowly) and be difficult to remove if you change your mind.
This and other species of Miscanthus grow so much during a single growing season that they are used for biomass energy production in Europe and Asia.
Steve Christman 7/15/00; updated 9/5/03