My cast iron plants are rusting
I planted 5 large cast iron plants around an oak tree several years ago. Ive noticed that the larger leaves have turned yellow in color and have brown edges. There are plenty of smaller healty looking leaves in each plant. Is it necessary to prune the discolored leaves from these plants on a regular basis. Also, can these be dug up and separated similar to a hosta? If so, what is the best time of the year to do that?