The Acanthus mollis took a pounding in the frost and snow but this is a tough species with deep roots. The large leaves do flop in sub-zero cold. If conditions improve after a short time they raise themselves up again. The recent cold spell was prolonged and that did for them but fresh growth is already going strong.

 The old leaves are turning to mush on the ground; in effect the plant is laying down its own mulch. I'm generally happy to for plants to decompose where they stand which returns nutrients to the soil.