Molinia is a genus that belongs to the family Poaceae and the tribe Gratioleae. There are two species of deciduous grasses in this genus. The species Molinia caerulea is commonly called purple moor grass, while the species Molinia arundinacea is known as tall moor grass. These grasses grow mostly in Europe and Asia and are commonly used as ornamental garden plants.
M. Caerulea can grow up to 35 inches (90 cm) tall in full sun or partial shade. They thrive in well-drained moist soil that is neutral to acidic. These grasses have leaves that arch widely and resemble fountains. From these fountain-like mounds emerge see-through flowers that start off green, turn purplish-brown, then finally turn yellow as the plant matures. The Molinia caerulea are versatile plants because they can be used for border planning, as partners to perennials, or potted up for the patio or indoor usage.
Another popular variety is the variegated moor grass, or Molinia caerulea variegata, which has green and milky white striped leaves that grow up to 30 inches (75 cm). The blades are typically about 0.3 inch (8 mm) wide and taper to a thin point. These plants are slow growing, and it takes about three years for them to reach maximum height, even when growing in ideal conditions. Their delicate upright flowers with yellow stems and purple spikes come out in the months of August to September. They can be attractive perennial borders because they are compact, and their flowers can look like a shimmering lace veil when blown by a slight breeze.
M. arundinacea, or tall moor grass, has arching and narrow leaves that are 2 inches (5 cm) wide and reach up to 4 feet (1.2 m) long. These grasses grow in clumps, and its transparent golden flowers with long, upright stems bloom from July to September. Their flowers can grow to a height of 8.3 feet (2.5 m). The grass is capable of self-sowing in the shade, but it cannot do so in full sun. They thrive well under the full sun in cool climates, but they need shade and adequate water in hot areas.
The Molinia arundinacea is used by golf course landscapers in areas near ponds or water courses. Home gardeners and landscapers often use them for borders, screening, or foliage. They can also be planted in areas where tall plants are needed, but where there is not enough space for bulky or heavy plants.