Molinia caerulea comes from the cool moors and bogs of Europe and western Asia, and it carries that heritage into the garden: it prefers moderate to moist soil, tolerates low fertility, and is in no rush to perform until the weather turns. The upright clump of flat narrow blades is handsome through summer but genuinely beautiful in fall, when the foliage shifts to golden yellow and the copper-brown flower stalks catch the light. Then, typically by late fall, both foliage and stalks break down and fall, leaving the ground effectively clear.

That collapse is worth knowing before you site it — Purple Moor Grass offers almost nothing in winter, which makes it a poor choice for a prominent mixed border but an excellent one alongside plants that hold their structure through the cold months. Cut any remaining material to the ground in late February or early March, just before the new blades emerge. It is slow to establish, but once settled in it fills out reliably and, notably, tolerates black walnut toxicity, a quality that is rarer than it sounds.