Hello, I saw some potential in this plum tree that had sprouted and grown from under a tree and reaching for sun it grew slowly and sideways. I harvested it August 31st and cleaned the roots and potted it. I chopped back a little so it wasn't going to tip the pot. My question is when and how far back can I chop without killing it? Also any suggestions on the style would be appreciated. The leaves are all pretty far out on the branches. Could I develop this as a cascade of sorts? Or eventually chop all the way back to that first potential leader?

thank you! mike