Jesse Saylor
Family
Poaceae
Botanical Name
Miscanthus 'Giganteus'
Plant Common Name
Giant Silvergrass
Special Notice
This entry has yet to be reviewed and approved by L2G editors.
General Description
A slow-growing, very tall-maturing perennial grass, the giant silvergrass is not foremost known for use in gardens, but as a potential biofuel source. Giant silvergrass is sterile (doesn't produce seeds), the result of genetically crossing Miscanthus sacchariflorus and M. sinensis. This hybrid first occurred naturally where both species existed in the same landscape. While the growth of the underground rhizome roots is slow, the above-ground canes and leaves of this warm-season grass is rapid. Plants sprout in spring, reaching maximum height and mass by late summer.
From an environmental standpoint, growing giant silvergrass as an agricultural crop provides many benefits. Cutting the foliage provides burning fuel, food for farm animals, or as a potential source to create ethanol. The plants sequester carbon dioxide from the atmosphere, stabilize soil, prevent erosion, provide wildlife cover and help filter water runoff. Once this grass is established, the maintenance input is quite low, with little need for supplemental irrigation or fertilizer applications.
Giant silvergrass becomes a tall clumping mass. The green leaf blades are long and narrow, flopping and arching with greater length. The stem is thick and sturdy, looking like a corn stalk or thin sugarcane culm. In mid- to late summer, the tops of each stem produces a fluffy, feathery cluster of tiny flowers. No seeds are produced. Frost kills the foliage, turning it shades of purple, rust and bronze before dropping away and leaving the naked stems. As with other ornamental grasses, the dead tissues are cut away by early spring to allow new growth to grow unimpeded and with access to full sunlight and air. Depending on agricultural use, giant silvergrass may be cut down in late summer (when green) for livestock food, or in winter (when fully dry) for use in construction or as fuel.
Grow giant silvergrass in full sun locations in a fertile, moist soil that has good drainage. In regions with very hot, dry summers, partial shade is best. This perennial grass does not tolerant soggy soils, but in the summer growing season does benefit from an evenly moist soil. Plants are established by planting rhizome cuttings. Once growing, expect one giant silvergrass to persist for about 15 to 30 years before naturally dying out. If grown strictly for garden ornamentation, plant giant silvergrass in a spacious location as it gets extremely tall. Use it in the background of a mixed border or as a tall hedge or screen. Cut back the dead foliage to just above soil level each late winter, and allow the plant to grow anew. In cold winter regions, giant silvergrass may not mature enought to flower before the onset of killing fall frosts.
'Giganteus' is often mislabeled or confused with Miscanthus floridulus, which does produce seeds and is also tall growing. The latter is less cold hardy and is known as the Pacific Island silvergrass or giant Chinese silvergrass.
