I am in Melbourne and I have this large birds nest fern which has been in the same pot in the same spot for about ten years and normally thrives. Early this winter the leaves started turning brown from the edges in, and now it looks like this. My partner had fed it with worm juice from the worm farm so I thought maybe it was just suffering from over fertilisation and I hoped that it would fix itself to no avail. The brown areas are dry and crispy, not soggy. Help please?