Originally from Africa and now grown as an annual across most of North America, Cenchrus setaceus — purple fountain grass in its most familiar cultivated forms — is one of those plants that changes a border composition dramatically. The foliage is burgundy to reddish-purple, the bottlebrush plumes that emerge in summer carry the same lavender-pink intensity, and together they create a color accent that reads as deliberate and sophisticated rather than accidental. It blooms from summer until the first hard frost, longer than almost any comparable ornamental grass, and the continuous display makes it a reliable workhorse for containers and bed backgrounds alike.

In zones 9 to 11 it can persist as a perennial, but across most of its range it is grown as an annual from transplants, mounding to 3 to 4 feet in full sun to light shade. It tolerates drought and arid conditions well and is entirely untroubled by deer. The self-seeding habit is vigorous enough to raise invasive concerns in some southern and western coastal states, so deadheading before seeds disperse is worth practicing in warmer regions. In zones where winter kills it back cleanly, this concern diminishes. The reddish-purple cultivars in particular are among the most effective color accent grasses available, holding their depth through the full growing season.