Purple Fountain Grass

The best companions for Purple Fountain Grass are plants that share its preference for full sun and lean, well-drained soil — and that create contrast without needing the same things at the same time. Black-eyed Susan (Rudbeckia hirta) and Coneflowers (Echinacea purpurea) both handle dry spells without complaint, and their yellow and pink blooms read sharply against the dark burgundy blades. Sedum and Lavender work for the same reason — low water needs, good drainage tolerance, and a completely different texture that makes the grass's arching habit more visible rather than less. Russian Sage adds soft blue-purple in an airy, open form that doesn't crowd the base.

Marigolds and Salvia fill in at 12–18 inches, tolerate heat, and keep the planting looking intentional while the grass does its thing. Ornamental Kale works as a cool-season bookend — it goes in when 'Rubrum' is winding down in fall, so the two rarely share the bed by more than a few weeks.

Black Walnut (Juglans nigra) is a hard no — it exudes juglone through its roots and leaf litter, and grasses planted within its drip line tend to yellow and stall rather than establish. Mint creates a different kind of problem: it spreads via underground stolons and will physically colonize the crown of the grass within a season or two, making it nearly impossible to remove cleanly. Impatiens is just a bad cultural fit — it wants consistent moisture and partial shade, so if you plant it next to 'Rubrum', one of them will always look rough.