Answer: Erianthus ravennae is often called hardy pampas grass. It is a perennial (although it is acting like a biennial!) and it is hardy down to zone 5. Since you're in zone 4, I would consider it marginal in your garden. I wonder if your winter temperatures were just too much for this plant? I'd dig it up and check the roots to make sure they're alive. If so, replant; if not, you may have to replace your lovely plant.
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