I still have Swiss Chard growing that I planted last summer. It seems as though it stayed protected from the layer of leaves I put on top of it last fall. Should I pull this or try to keep it growing?

I had celery that survived last years ('09 - '10) winter however last summer it was skinny and didn't grow nearly as well as the new celery I had planted last summer. The 2 year old celery is still growing believe it or not. I don't have the heart to yank it.