Porcupine Grass (Miscanthus sinensis ‘Strictus’) is a widely favored ornamental grass due to its striking appearance and manageable growth. Many gardeners often wonder if this robust plant might be invasive. Generally, Porcupine Grass is not considered invasive in most regions. This particular cultivar exhibits a clumping growth habit, meaning it expands gradually from its base rather than spreading aggressively through runners or prolific self-seeding.
Characteristics of Porcupine Grass
Porcupine Grass is an ornamental grass with an upright, columnar growth habit. Its stiff, erect leaves feature unique horizontal yellow bands, resembling porcupine quills, which gives the plant its common name. This warm-season grass typically forms dense clumps, growing 5 to 9 feet tall, including its flower plumes, with a spread of 2 to 6 feet.
In late summer or early fall, Porcupine Grass produces feathery plumes that emerge in shades of pink or reddish-brown. These plumes transition to a silvery or beige color as they mature, providing visual interest through fall and winter. The plant’s architectural form and persistent plumes add texture and vertical appeal to garden landscapes. It thrives in full sun to partial shade and adapts to various soil types, preferring medium moisture but tolerating drought once established.
Is Porcupine Grass Truly Invasive?
While the species Miscanthus sinensis, or Chinese Silver Grass, is considered invasive in many parts of the United States, the ‘Strictus’ cultivar behaves differently. The distinction lies in its growth pattern and seed viability. Porcupine Grass is a clump-forming plant, meaning its root system expands slowly outward from a central point, maintaining a contained footprint.
Invasive plants spread rapidly through prolific self-seeding or extensive rhizomatous growth, outcompeting native vegetation. While Miscanthus sinensis ‘Strictus’ can produce viable seeds, studies indicate significantly lower seed production compared to other Miscanthus cultivars or the wild species. For example, a 2010 study found ‘Strictus’ produced 907 viable seeds, substantially less than other varieties. While some Miscanthus cultivars touted as sterile are not entirely so, the clumping nature and reduced seed fertility of ‘Strictus’ typically prevent it from becoming a high-risk invasive plant in most garden settings.
Managing Porcupine Grass in the Garden
Despite its non-aggressive nature, Porcupine Grass is a sizable plant that benefits from routine maintenance to keep it looking its best and contained. Cut back the dried foliage in late winter or early spring, just before new green shoots emerge. This process not only tidies the garden but also encourages vigorous new growth for the upcoming season.
To manage the plant’s size and vigor, division of the crown every few years is beneficial. This is best performed in the spring as new growth appears, providing an opportunity to propagate new plants or reduce the existing clump’s size. While ‘Strictus’ has low self-seeding, deadheading the spent flower plumes after they fade in the fall can minimize unwanted seedlings. Applying mulch around the base of the plant can also help suppress any reseeding.
Alternatives to Porcupine Grass
For gardeners seeking alternatives with a similar aesthetic to Porcupine Grass and no risk of invasiveness, several native ornamental grasses provide excellent choices. These options mimic the upright form and interesting texture without concerns about uncontrolled spread.
Switchgrass (Panicum virgatum) is a clumping grass that comes in various cultivars, offering blue-green foliage that transitions to golden-yellow or bronze hues in the fall. Little Bluestem (Schizachyrium scoparium) has blue-green leaves that turn reddish-bronze in autumn, providing a dense, upright form. Prairie Dropseed (Sporobolus heterolepis) offers a finer texture with arching, emerald-green foliage and airy, scented seedheads. These native grasses provide comparable visual appeal while supporting local ecosystems.