I have kafir lilies Kaz. The plant stays green all year. I'll send you some if you'd like, when I cut them back and divide after flowering in the next few weeks.
Of course watercress stays green all year round but doesn't grow in the winter so whatever size you have in at the end of autumn is what stays green all winter. It is worth having some if nothing else is there in the winter months just to break up the coldness look of winter water.