Giant Miscanthus (Miscanthus × giganteus): A Perennial Biomass Crop (FS-2024-0734)

Giant miscanthus is a sterile hybrid, which must be propagated vegetatively, typically by rhizomes. Other miscanthus species, which are used primarily by the landscape industry, are not sterile and can become a problem for local environments through seed dispersal. However, giant miscanthus is the result of a cross between Miscanthus sinensis and Miscanthus sacchariflorus which have two different ploidy levels, diploid and tetraploid, respectively. The result of this cross is Miscanthus x giganteus, which is a triploid hybrid, like seedless watermelons. Triploids do not produce viable seeds, and therefore giant miscanthus is not able to become invasive via seed propagation (Wilson & Heaton, 2013a). The inability of giant miscanthus to produce viable seed, along with its high yields, may make it a more desirable biomass crop than other commonly used biomass crops, such as switchgrass (Panicum virgatum L.). Switchgrass does produce viable seed and has become a nuisance in some of the areas of the country where it was being grown for biofuels (USDA NRCS Plant Materials Program, 2001).

Giant miscanthus rhizomes grow in a clump forming growth pattern, expanding about one foot per year for the first three years. However, giant miscanthus has not been found to spread aggressively via rhizome propagation like other rhizome spreading species, such as johnsongrass (Sorghum halepense L.), and it is not observed to move beyond its planted field boundaries except in cases of soil disturbance. The biggest risk for unwanted propagation of giant miscanthus is via erosion and water movement, so it should not be planted in shore stabilization where wave action is expected. Giant miscanthus rhizomes planted immediately adjacent to streams and ditches could erode and travel along a waterway to start a new stand. Giant miscanthus can be terminated with herbicides; however, multiple treatments might be required over successive years (Vollmer & Rogers, 2024). For more information, see FS-2023-0685, Considerations for Terminating Giant Miscanthus on Maryland Farms (Vollmer & Rogers, 2024).

Giant miscanthus should be planted in soil where the pH is between 5.5 and 7.5 (Kalmbach et al., 2020). Giant miscanthus can be grown on different soil types from sandy soils to heavy clay soils. Research in the United Kingdom demonstrated that giant miscanthus yields higher on soils with higher moisture retention such as clay soils (Richter et al., 2016). Ideally, giant miscanthus will be grown in areas with at least 30 inches of rainfall expected per year (Williams & Douglas, 2011). The average rainfall in Maryland is 43.6 inches per year (National Integrated Drought Information System, 2024). Giant miscanthus can be grown on land with wet or salty conditions, with expected lower yields compared to prime farmland. For more detailed information see FS-2024-0735, Growing Giant Miscanthus on Marginal Land: A Sustainable Solution for Challenging Conditions (Hirsh et al., 2025).

In plant hardiness zones six or higher, giant miscanthus rhizomes can be planted in fall (Figure 2). In zones four-six, giant miscanthus rhizomes do best planted in early spring after the last frost. Giant miscanthus is prone to winter kill in zones lower than four. Soil temperatures should be above 50°F for emergence. If giant miscanthus is planted at a site where over-winter waterlogging may occur, spring planting is preferable to prevent rhizomes from rotting in saturated soil. Rhizomes can be planted with a specialized planter (Figure 3), but farmers have also successfully used other creative methods to bury rhizomes, such as a modified potato planter. For small areas, planting by hand is often the simplest method. The planting equipment should deposit two to four inches of soil over the rhizomes, with a spacing of two feet between rows and two feet between plants within rows (Wilson & Heaton, 2013a). Good soil to rhizome contact is essential for plant establishment. For more detailed information on planting giant miscanthus see Williams and Douglas (2011).

Giant miscanthus has low nutrient requirements. Nitrogen application is unnecessary in the first year of growth, because it can increase weed pressure.

For more information about fertilization please see EB-443, Soil Fertility Recommendations: Nitrogen, Phosphorus, and Potassium Requirements of Miscanthus (Kalmbach et al., 2020).

While giant miscanthus will outcompete weeds once it is established (year 3), herbicides are recommended during the establishment phase (Wilson & Heaton, 2013b). Giant miscanthus has even been shown to outcompete phragmites (Phragmites australis ssp. australis) on marginal land. Giant miscanthus can be grown in fields with deer pressure, and results from the University of Maryland study on marginal land with heavy deer pressure has shown that deer pressure does not cause yield losses. For more details, see FS-2024-0735, Growing Giant Miscanthus on Marginal Land: A Sustainable Solution for Challenging Conditions (Hirsh et al., 2025). Although some rust has been observed in the Midwest, pest and disease damage on giant miscanthus is negligible and pesticides are not required (Hively, personal communication).

The dry biomass material is harvested once annually between November and March. Standard forage or silage harvesting equipment such as choppers, mowers and balers can be used to harvest giant miscanthus (Figure 4). After harvest the giant miscanthus material can be trucked directly to a buyer, stored in bulk (e.g., silage bags), or stored in bales.

The biomass can be used for animal bedding, bioenergy, or as a raw material for fiber and various industrial applications (Jacobson, 2024). Giant miscanthus also has environmental uses including erosion control and carbon sequestration. Giant miscanthus can be planted on field borders, which can scavenge nitrogen from groundwater prior to entering streams and ditches. Giant miscanthus is currently used in Maryland as a poultry bedding source, which functions the same as traditional pine chip bedding but is more sustainable. During harvest for giant miscanthus that will be used as poultry bedding, the dry giant miscanthus is chopped into one inch size pieces and is stored or even directly transported into the poultry houses. If considering growing giant miscanthus, it is important to secure a market or buyer prior to investing in this perennial crop.

• National Integrated Drought Information System. (2024). Drought in Maryland. Retrieved October 10, 2024, https://www.drought.gov/states/maryland#:~:text=Maryland%20has%20an%20average%20rainfall,but%20this%20varies%20by%20region. 
• Heaton, E., Moore, K., Salas-Fernandez, M., Hartzler, B. Liebman, M. & Barnhart, S. (2010). Giant Miscanthus for Biomass Production. (AG201). Iowa State. https://store.extension.iastate.edu/product/12611
• Hirsh, S., Sater, H., & Moyle, J. (2025). Growing Giant Miscanthus on Marginal Land: A Sustainable Solution for Challenging Conditions (FS-2024-0735). University of Maryland. https://go.umd.edu/FS-2024-0735
• Jacobson, M. (2024). Energy crop profile: Giant miscanthus. Penn State Extension. https://extension.psu.edu/energy-crop-profile-giant-miscanthus
• Kalmbach, B., Toor, G., & Ruppert, D. (2020). Soil Fertility Recommendations: Nitrogen, Phosphorus, and Potassium Requirements of Miscanthus (EB-443). University of Maryland. https://extension.umd. edu/resource/soil-fertility-recommendations-nitrogen-phosphorus-andpotassium- requirements-miscanthus-eb-443
• Richter, G. M., Agostini, F., Barker, A., Costomiris, D., & Qi, A. (2016). Assessing on-farm productivity of Miscanthus crops by combining soil mapping, yield modeling and remote sensing. Biomass and Bioenergy, 85, 252-261.
• USDA NRCS Plant Materials Program. (2001). Switchgrass Panicum virgatum L. https://plants.usda.gov/DocumentLibrary/factsheet/pdf/fs_pavi2. pdf
• Vollmer, K., & Rogers, E. (2024). Considerations for terminating giant miscanthus on Maryland farms (FS-2023-0685). University of Maryland. https://extension.umd.edu/sites/extension.umd.edu/files/publications/FS-2023-0685_ConsiderationsForTeminatingGiantMiscanthus_ada.pdf
• Williams, M. J., & Douglas, J. (2011) Planting and managing giant miscanthus as a biomass energy crop. Technical Note No. 4. USDA NRCS Plant Materials Program. https://www.nrcs.usda.gov/plantmaterials/flpmstn10548.pdf
• Wilson, D., & Heaton, E. (2013a). Giant miscanthus establishment (PM3056). Iowa State. https://store.extension.iastate.edu/product/14006
• Wilson, D., & Heaton, E. (2013b). Giant miscanthus weed control (PM3055). Iowa State. https://store.extension.iastate.edu/product/Giant-Miscanthus-Weed-Control