Imperata cylindrica 'Rubra' is a warm-season ornamental grass grown primarily for foliage color. Leaves emerge green with red tips in spring and deepen to full crimson by fall, making it one of the few grasses used as a color accent rather than for structure or seed interest. It works well in borders, containers, and as a contrast to blue or silver foliage plants.
This cultivar spreads slowly by rhizomes and stays compact. Full sun produces the most intense red; shade causes growth to trend predominantly green. Keep soil evenly moist during establishment. The parent species, Imperata cylindrica (cogongrass), is a federally listed noxious weed across much of the southern US. Any shoots that revert to solid green must be removed and destroyed immediately to prevent potential spread. Some states restrict or ban the sale of this cultivar — confirm local regulations before planting. Soil pH of 5.5–6.5 suits it best, and a light mulch layer helps retain the consistent moisture it prefers.
Rhizomes of Imperata cylindrica are used in traditional Chinese medicine under the name Bai Mao Gen to stop bleeding, reduce fever, and treat urinary tract inflammation. This pertains to the species broadly; the ornamental cultivar is not harvested for medicinal use.
Rust
Orange to brown raised pustules on the undersides of leaves, with yellow spotting on the upper surface. Heavy infections cause leaves to yellow and drop.
Remove and destroy infected leaves. Avoid overhead watering and improve air circulation. Apply a sulfur or copper-based fungicide if it spreads. Clear plant debris in fall.
Fungal leaf spot
Brown or purplish spots on the leaves, often ringed with a yellow halo, that spread and merge in warm, humid, or wet weather; heavily spotted leaves yellow and drop early.
Pick off spotted leaves and clear fallen debris to remove overwintering spores. Improve air circulation by thinning, and water at the base so foliage dries quickly. If it persists, apply a copper- or sulfur-based fungicide at the first sign.
Crown Rot
Lower leaves yellow and wilt; the base of the rosette turns brown and soft, sometimes with white fungal threads at the soil line. Plants collapse in wet conditions.
Remove and destroy affected plants. Improve drainage and avoid overhead watering. Do not mulch directly against the crown. Space plants for airflow and avoid replanting in the same wet spot.