Plant library · Ornamental Grasses
Leymus arenarius
Blue Lyme Grass is a bold, blue-gray perennial grass that brings upright, wheat-like summer spikes to a sunny planting. At about 3 feet tall and 3 feet wide, it reads as a substantial textural mass rather than a fine edging grass. Its vigorous habit makes it better suited to places where its boundaries are deliberate and easy to inspect.
Use it as a contained accent beside a broad path, against a wall, or in a large planter where its arching foliage and summer seed spikes can be seen at close range. Keep it out of tightly mixed borders, narrow foundation beds, and planting pockets shared with slower-growing perennials. Give it open space on at least one side so new shoots are visible before they reach neighboring plants or circulation areas.[1][2]
Set plants 2½ feet apart, center to center, for a continuous-looking planting; each clump can fill roughly 3 feet across at maturity. In a repeated row, reserve a clear edge along a path or bed boundary rather than allowing the planting to blend into smaller neighboring plants. Treat the 3-foot footprint as the designed clump size, not as a permanent limit on spread in open ground.
Place Blue Lyme Grass in full sun, where its blue-gray foliage and upright spikes will not be shaded by taller shrubs or trees. It suits low-water layouts and well-drained ground. A dry, exposed strip or a raised bed edge gives the grass a setting that is easier to maintain and monitor than a lush, closely planted border.[1][2]
Summer brings the bold spikes that rise above the foliage, extending the plant’s vertical presence when nearby low perennials may be less prominent. The foliage can remain visually useful beyond the flowering period. Allow enough room around the clump for fall cleanup without stepping through adjacent planting.[1][2]
This grass spreads aggressively by rhizomes and can outgrow an informal planting area. Use a container, a bed with firm boundaries, or a site where expansion is acceptable and regularly managed. Do not rely on ordinary plant-to-plant spacing alone to restrain it; leave access for checking and removing outward-moving shoots before they occupy adjacent ground.[1][2]
Editorial content updated 2026-07-20.