Champions of the Prairie: The Essential Roles of Warm-Season Grasses

By Mandy Komes-Leifheit

Warm-season grasses make up a significant majority of Illinois prairie ecosystems, often accounting for more than 50% of the plant biomass. In tallgrass prairies, dominant species such as Andropogon gerardii (Big Bluestem), Sorghastrum nutans (Indiangrass), Panicum virgatum (Switchgrass), and Schizachyrium scoparium (Little Bluestem) thrive in the summer months and can reach impressive heights.

🌱Ecological Powerhouses

These grasses aren’t just tall—they’re tough, too. Warm-season grasses play critical roles in prairie ecosystems.

Soil Stability: Their deep, fibrous root systems help anchor soil, reduce erosion, and improve soil structure.

Carbon Storage: They store large amounts of carbon underground, helping mitigate climate change by locking it in the soil long-term.

Wildlife Habitat: Dense stands of grasses offer shelter and nesting areas for birds, insects, and small mammals. Species like A. gerardii and P. virgatum create complex vertical structures that support diverse fauna.

Water Quality: These grasses filter runoff and reduce nutrient leaching, which contributes to cleaner streams and waterways.

Biodiversity & Resilience: Their seasonal growth complements that of cool-season plants, promoting year-round habitat diversity and strengthening resistance to invasive species.

🌾What Is a Warm-Season Grass?

Warm-season grasses emerge in late spring to early summer, with flowering extending from mid to late summer, and sometimes into early fall. Their ornamental value can persist into fall and even winter.

They begin actively growing when soil temperatures consistently reach 60–65°F and air temperatures are around 70–75°F. This means they’re often slow to wake up in cooler springs—so don’t panic if your Sporobolus or Schizachyrium are taking their time. They’re just waiting for the warmth!

Some warm-season grasses are better suited for residential landscapes than others. These species tend to be well-behaved and manageable in home landscapes.

🌱Great for Gardens:

Bouteloua curtipendula (Sideoats Grama)
Chasmanthium latifolium (River Oats)
Eragrostis spectabilis (Purple Lovegrass)
Schizachyrium scoparium (Little Bluestem)
Sporobolus heterolepis (Prairie Dropseed)

Keep in mind that some of these prefer wetter soils than others, so be sure to select species that works with site conditions.

⚠️Caution in Smaller Spaces, Andropogon gerardii and Sorghastrum nutans are both aggressive growers. While they’re workhorses in prairie restoration and habitat projects, they can easily take over smaller garden settings. These plants have a job to do—just maybe not in your flower bed!