Growing multiple grape varieties in the same hole
I am interested in growing two or more grape varieties from the same ground hole in an espalier fashion (why? because of space constraints). Pardon my ignorance about grape species, but I am considering between green, red and black grape vines.
I'd like to know if doing so is a wise idea or will lead to problems down the road, such as disease or one species dominating the other. Please let me know your thoughts. I am a novice in this area and would very much appreciate any input.