In the Southeastern US, livestock producers rely on forages as the basis of their operations. During the summer, many commonly used perennial forages (including bermudagrass and bahiagrass) will produce high quality forage in the mid-summer months but will have slow growth in the spring and early summer. Others, like tall fescue, will go dormant in mid-summer. Native warm-season grasses such as indiangrass, little bluestem, big bluestem, switchgrass and eastern gamagrass will peak in production in late spring and summer, after cool season forages have stopped growing. This peak allows for increased forage quantity over the hotter months.
Planted perennial forages in the Southeast may be susceptible to climate change, namely increasing annual temperature and variable precipitation. To meet the challenges that these effects pose to producers, forage systems must adapt and become increasingly resilient. Native warm season grasses are better suited to thrive in variable precipitation due to deep and hardy root systems and can continue to produce in non-ideal conditions.
Warm-season native grasses encompass the following:
Indiangrass (Sorghastrum nutans) is a perennial that starts growing in April, peaks in late June and declines through August. Grazing indiangrass should begin when stand height is 24 to 30 inches tall and should be rested at a stubble height of 12 inches. Indiangrass can grow up to 3-7 feet in height and has a deep root system that allows for increased drought resistance.
Little bluestem (Schizachyrium scoparium) is a perennial bunch grass that will grow from April to a peak in early July, then decline through August. Little bluestem will grow up to 4 feet and should not be grazed below a stubble height of 12 inches, and can grow in low quality, drought prone soils.
Big bluestem (Andropogon gerardii) is a perennial rhizome clump grass that can grow up to 8- 9 feet tall and will grow from April with a peak in growth after June 1, then decline through August. Big bluestem is a hardy grass that can grow in poor soil with low pH and is particularly drought resistant due to its ability to develop root systems up to 12 ft below ground. It should not be grazed below 12 inches.
Switchgrass (Panicum virgatum) is a perennial grass that spreads by rhizomes and seed but is usually seen in clumps. Switchgrass is an earlier-maturing than most other warm-season native grasses, with growth beginning in April and production peaking in late May- early June, then declining through July and August. Switchgrass has an extensive root system which makes it a drought tolerant option for forage but can also be productive on wet sites. Some varieties are even tolerant to extended periods of flooding. It should not be grazed below 12 inches
Eastern gamagrass (Tripsacum dactyloides) grows relatively consistently from April to mid-July, then declining through August. It provides excellent quality forage over a long season, making it a good option for incorporating into grazing systems. Eastern gamagrass grows well in moist, well-draining soils with good soil fertility, but is not tolerant of flooding. It should not be grazed below 12 inches
Establishment of native-warm season grass systems
Establishing native warm season grasses requires complete removal of any previously perennial grass stands, including tall fescue and bermudagrass. Removal of planted grasses will differ based on available seedbank and chosen removal techniques.
To improve establishment and growth, it is recommended to test soil and be aware of any nutrient deficiencies. Native grasses can tolerate much lower fertility soil with more extreme pH levels compared to planted grasses. Poor fertility may have the side benefit of reducing weed pressure, allowing for more effective establishment. Because of this, it is not recommended to apply any additional N in the establishment year. Generally, if pH is above 5.0 and P and K are above ‘low’ levels on soil tests, native grasses can thrive and will not require supplementation.
Planting windows are from April through June. Planting can happen later in the summer, but dry periods are more likely and will affect germination rates and initial growth. By planting in the spring, native seeds will be able to start growing in ideal conditions and produce throughout the rest of the warm season. Generally, it will take 2 years for native warm season grass stands to establish, as germination rates are variable, and seedling growth can be slow. To support this growth pattern, it is not recommended to graze or hay native warm season grass stands until the second year of establishment, pending the stand status.
Native warm season grasses are a climate tolerant and nutritionally viable forage option for grazing systems in the southeastern US. As the producers grapple with the effects of climate change, including variable and unpredictable precipitation and increasing global temperatures, building resilient and productive grazing systems is vital to sustain food security and the agriculture industry as a whole. Utilizing climate smart practices such as establishing native warm season grasses can help promote climate resiliency and allow producers to maintain production despite environmental pressures.
Written by
Hannah Malcomson, Ph.D. student
Liliane Silva, Forages Specialist
