Q.sweet potato ornamental varieties
Do I need special sweet potatoes to grow the 4 varieties: Sweet Carolina/purple, Blackie, Marquerite (green) and Tri-Color? What do I use for seed potatoes for the various colors?

You can purchase tubers or plants for these specific varieties at your local garden store.
For more information on ornamental sweet potatoes, please visit the following link:
https://www.gardeningknowhow.com/edible/vegetables/sweet-potato/grow-sweet-potato-plant.htm