Struggling with Blue Flag Iris — would appreciate advice

I want to be honest: I'm not getting great results with Blue Flag Iris and I'm not entirely sure why. frost damage on tender varieties left in shallow water has been a recurring problem despite my attempts to address it. I've been focusing on removing dying foliage in autumn before it rots and reduces water quality based on everything I've read.

essential habitat and breeding ground for pond wildlife is there in glimpses, which tells me the plant has potential in my conditions. I have it in an indoor water feature with appropriate species which might not be ideal. overwintering dormancy in the pond bed showed some improvement. Two stars for now — not the plant's fault, but not a success yet. I'll update if things improve.