Aspects of the invention are directed to fabrication methods and resulting structures for providing transistors having hybrid crystal orientation channels and mixed crystal orientation bottom epitaxies. In a non-limiting embodiment, a first fin having a first crystal orientation is formed in a first region of a substrate having a second crystal orientation. A second fin having the second crystal orientation is formed in a second region of the substrate. The second fin is formed directly on a surface of the substrate. A mixed crystal bottom source or drain region is formed between the first fin and the first region of the substrate and a single crystal bottom source or drain region having the second crystal orientation is formed on sidewalls of the second fin and on the surface of the substrate in the second region.