Sorghastrum, commonly known as Indiangrass. This tall, warm-season grass is a significant component of the North American prairie and offers a lot to the landscape.

What Makes Sorghastrum So Special?

• Native Status and Ecological Importance: Sorghastrum nutans (the most commonly cultivated species) is a dominant grass of the tallgrass prairie ecosystem, a critically important and increasingly rare habitat in North America. Planting it helps restore and support this ecosystem, providing food and shelter for wildlife.
• Golden Fall Color: Its most striking feature is its beautiful golden-yellow to orange-bronze fall color, which provides a warm glow in the autumn landscape. This color often persists through the winter, adding interest to the dormant season.
• Plumes: The airy, golden seed heads (plumes) are quite showy and add a delicate texture to the garden. They shimmer in the sunlight and sway gracefully in the breeze.
• Wildlife Value: Provides food (seeds) and cover for birds and other wildlife. It is a larval host plant for several butterfly species.
• Drought Tolerance: Once established, it is exceptionally drought-tolerant, making it a good choice for water-wise landscapes.
• Adaptability: Grows well in a range of difficult conditions.

Description

• Foliage: Blue-green to gray-green leaf blades during the growing season, turning golden-yellow to orange-bronze in the fall. The leaves are typically flat and relatively wide (up to ½ inch).
• Flowers/Seed Heads: Large, airy, golden-bronze plumes that appear in late summer and persist into winter. The plumes are composed of many small spikelets, each with a distinctive, twisted awn (a bristle-like appendage).
• Growth Habit: Upright, clump-forming, warm-season grass. Typically grows 4-7 feet tall, sometimes taller.
• Stems: Sturdy, upright stems that are often reddish or purplish at the base.

Details

• Bloom Time: Late summer to fall (typically August-October).
• Hardiness: Generally hardy in USDA zones 4-9.
• Sunlight: Prefers full sun (at least 6 hours of direct sunlight per day).
• Soil: Adaptable to a wide range of soil types, including clay, loam, and sandy soils. Prefers well-drained soil but can tolerate occasional wetness.
• Drought Tolerance: Highly drought-tolerant once established.
• Deer Resistance: Generally considered deer-resistant.
• Attracts Wildlife: Provides food and cover for birds, small mammals, and insects.
• Salt Tolerance: Moderate salt tolerance.

Native Habitat

Sorghastrum nutans is native to North America, primarily the tallgrass prairie region of the central and eastern United States and Canada. It is found in prairies, meadows, open woodlands, and along roadsides.

Landscaping Design Tips

• Prairie Gardens: A must-have for prairie gardens and restorations.
• Meadow Gardens: Excellent for meadow-style plantings, providing vertical structure and fall color.
• Mass Plantings: Creates a dramatic effect when planted in large masses or drifts.
• Backdrops: Use as a backdrop for shorter perennials and grasses.
• Screens: Can be used to create a visual screen or privacy hedge.
• Focal Points: Its tall stature and showy plumes make it a good focal point in the garden.
• Winter Interest: Provides excellent winter interest with its persistent foliage and seed heads.
• Erosion Control: Its deep root system helps stabilize soil and prevent erosion.
• Companion Plants:
• Other prairie grasses, such as Andropogon gerardii (Big Bluestem), Schizachyrium scoparium (Little Bluestem), and Panicum virgatum (Switchgrass).
• Prairie wildflowers, such as Echinacea purpurea (Purple Coneflower), Rudbeckia hirta (Black-eyed Susan), Solidago (Goldenrod), and Aster.

Planting and Care

• Planting: Plant in spring or fall. Space plants 2-3 feet apart.
• Watering: Water regularly during the first growing season to establish a strong root system. Once established, it is very drought-tolerant.
• Fertilizing: Generally, does not require fertilization. Excessive fertilization can lead to floppy growth.
• Pruning: Cut back to the ground in late winter or early spring before new growth emerges.
• Division: Divide clumps every few years in spring if they become too large or overcrowded. This is not typically necessary for its health.
• Pests and Diseases: Generally, pest and disease-free.

Taxonomy

• Kingdom: Plantae
• Phylum: Angiosperms
• Class: Monocots
• Order: Poales
• Family: Poaceae (Grass family)
• Genus: Sorghastrum
• Species: nutans (most common in cultivation)

Morphology

• Roots: Deep, fibrous root system.
• Stems: Erect, sturdy, often reddish or purplish at the base.
• Leaves: Linear, flat, blue-green to gray-green, turning golden-yellow to orange-bronze in fall. A key identifying feature is a small, pointed "claw" or "ligule" where the leaf blade meets the sheath.
• Flowers/Seed Heads: Inflorescences are large, terminal panicles (branched clusters) with a golden-bronze color. Spikelets are small, with twisted awns.

Popular Varieties

• Sorghastrum nutans 'Indian Steel': A cultivar with blue-gray foliage and a more upright habit.
• Sorghastrum nutans 'Sioux Blue': Another cultivar with blue-gray foliage.
• Sorghastrum nutans 'Golden Sunset': Selected for its intense golden-yellow fall color.

Other Insights for Gardeners

• Warm-Season Grass: Sorghastrum is a warm-season grass, meaning it actively grows during the warmer months (spring, summer, and early fall) and goes dormant in winter.
• Slow to Establish: It can be slow to establish, so be patient during the first year or two.
• Aggressive Spreader (Potentially): While generally clump-forming, Sorghastrum nutans can spread via rhizomes in some situations, particularly in loose, sandy soils. This is generally less of a concern than with some other grasses, but it is something to be aware of.
• Fire Adapted: Like many prairie plants, it is adapted to periodic fires, which help maintain its vigor and prevent the buildup of thatch.

In summary, Sorghastrum, particularly Sorghastrum nutans, is a magnificent native grass that offers striking fall color, showy plumes, and excellent wildlife value. Its adaptability, drought tolerance, and low-maintenance nature make it a valuable addition to a variety of landscapes, especially those aiming to recreate the beauty and ecological benefits of the North American prairie. Its strong vertical presence adds structure and movement to the garden.