Rootstock Determines the Size of the Tree
The rootstock is the lower portion of the tree that you don’t see. Rootstock selection and pruning determine the size of a tree. If you have limited space, choose a dwarf or semi-dwarf rootstock and keep it well pruned. If you want a tree to hang a hammock on, or to use as windbreak or shade, go for a semi-standard or standard. The diagram below shows the relative sizes of different rootstocks.