Orange tree in container
I am a newbie to this forum, so if my question is basic or has been covered a million times, please understand or shunt me to the proper thread.
I have an orange tree in a five gallon container that has done well ever since it was a seedling. My mother-in-law, now deceased, gave it to one of my kids. She had started it from an orange seed in a styrofoam cup about ten years ago. I have moved it into progressively larger contaners over the years and it survived on our deck in the warmer months here in zone 6 and we moved it to a sunny indoor location in the winter. It is about 5'6" tall at this point.
As I approach retirement, I have decided to pursue container gardening and bonsai as a hobby, things I have always wanted to do. Reading about soil mixes has made me realize my mistake of using potting mixes for this orange tree. I want to repot it--into the same size container because I do not want the tree to get any larger.
What soil mix woudl be good for this tree? Any advice is welcome.