Hi there. I have a teddy bear magnolia that is looking terrible. The leaves are shrivelled and brown and any new green ones are breaking away. Some of the stems/branches are green and others a dead/dry looking texture. We definitely over pruned it but surely that has not caused it to be in such bad shape. This tree has great sentimental importance to us so any advice would be great. Also, we live in Sydney Australia and the tree is in the sun most of the day. Thank you so much!!
It needs acidic, well drained, nutrient rich soil. If you can, it would do better planted in the yard in full to part sun. Or at least in a larger container with acidic soil. Also, be sure to discard any leaves that fall to help prevent fungal spots next year. Pruning more than 1/3 of a tree at a time can be detrimental. Here is more on its care that should help:
https://www.gardeningknowhow.com/ornamental/trees/magnolia/magnolia-evergreen-varieties.htm
https://www.gardeningknowhow.com/ornamental/trees/magnolia/pruning-magnolia-trees.htm