Answer: Winter stress can turn these off color, poor rooting can cause foliage problems, as can overwatering. Underwatering could also cause them to brown. Based on your description I am not sure what has happened to them. And since they are relatively newly planted they may not have rooted well before winter weather arrived. I hate to give up on plants, but without seeing them it is very hard to say whether they will be okay in the long run, or not.
Q&A Library Searching Tips