Plant library · Ornamental Grasses
Molinia caerulea
Purple Moor Grass is a clumping perennial that brings a compact green base and airy, purple-tinged flower stems to a planting from late summer into fall. At about 3½ feet tall and 2 feet wide, it adds vertical movement without demanding the broad footprint of a large shrub. Use Molinia caerulea where its fine stems can rise through lower neighboring plants while the foliage mound remains easy to reach.
Set it in the middle or back of a sunny border, or repeat it through a meadow-style or rain-garden planting where moderately moist ground is available. Its narrow, open flowering stems suit positions beside denser perennials, allowing the planting behind and around it to remain visible. Keep the crown out of path edges and narrow entries: leave a planting-side reach-in zone so fallen late-season stems and spring cleanup do not spill into circulation space.[1][2]
Plant on 2-foot centers for a continuous rhythm of individual clumps. That spacing matches its roughly 2-foot mature width, so plants can meet lightly without being forced into a crowded block. In a border, measure spacing from the crown rather than from the tips of the flowering stems; the stems create a taller, looser layer above the main footprint. Allow a little extra room beside low walls, steps, and paths for maintenance access.
Give Purple Moor Grass full sun and moderate water, with soil that does not dry out rapidly. Place it where moisture is steadier than in a hot, fast-draining edge, such as a lower section of a border or near a rain-garden zone. Moist, well-drained ground supports a tidy clump while avoiding the need to place it in a permanently wet basin.
The flower display carries the planting into late summer and fall, then foliage and stems shift toward gold before breaking down. Treat it as a seasonal screen rather than a permanent winter structure, since the old growth commonly collapses by late fall or early winter. Leave enough access to cut the remaining foliage to the ground in late winter or early spring, just before new growth starts.[1][2]
This grass can take time to settle into its allotted space. Avoid filling its 2-foot center-to-center planting pattern with temporary plants that will be difficult to remove later; instead, use short-lived seasonal color only where it can be cleared without disturbing the crown. Its deer resistance can help guide placement in exposed beds, but it should still be positioned for its moisture and sun needs first.
Editorial content updated 2026-07-20.