A: Not quite yet, if you can avoid it.
Ornamental grasses often still have nice texture even as they go dormant, so we’re never in a hurry to cut them back. But there’s another reason altogether to not rush to do this! A number of the ornamental grasses can be damaged by the severe cold of an ice storm or extended freezing event, and leaving that top foliage up until late February or even early March will give them more insulation over their roots and crown. Damage from that cold weather doesn’t happen every year, but it can be substantial when it does and even cause younger clumps in particular to die outright, or come out so poorly that it’s July before you have much to look at.
Do your cutbacks in late winter, before the new growth starts peeking up, and you’ll keep a nice, clean appearance on your ornamental grass.
Burton specializes in diagnosing and solving plant problems. If you have a question for Burton, please email him at burton@covingtonnursery.com and include photos showing the problem.