How to Prune Indian grass?
Cut down dead foliage and old flowered stems, just before growth commences in spring

Indian grass · Molinia caerulea
Also known as: lavender grass; purple moor-grass
Will grow in full sun or part shade in any moderately fertile, moist but well-drained soil, but prefers neutral to acidic soil. See ornamental grasses cultivation
Cut down dead foliage and old flowered stems, just before growth commences in spring