Purple Sweet Potato (FRESH PRODUCT). PURPLE SKIN

  Hawaii Purple Sweet Potato. Stores well.

It is a unique colored sweet potato that is reddish purple inside, and the most consumed potato in Okinawa. The purple color contains polyphenol which has antioxidant effect, used for cooking, sweets such as cake and ice cream, cosmetic, and other various uses.
I have started Okinawan Sweet Potatoes in seven half-whiskey barrel containers.
I got just as much yield from the container as I did from a Raised Bed, but it was so much easier to harvest the Okinawan Sweet Potatoes in the container. It would take me a over an hour to dig up the Raised Bed and find all of the Okinawan Sweet Potatoes. With the container, all I had to do was to dump the container onto some newspapers and the Okinawan Sweet Potatoes would just appear. No digging. No hunting.
Start the Slips
Sweet potatoes aren't started by seed like most other vegetables, they're started from slips. Slips are shoots that are grown from a mature sweet potato.
To start your slips, you need several healthy, clean sweet potatoes. Each sweet potato can produce up to 50 slip sprouts. To create sprouts, carefully wash your potatoes and cut them either in half or in large sections. Place each section in a jar or glass of water with half of the potato below the water and half above. Use toothpicks to hold the potato in place 
The slips need warmth, so put them on a window ledge or on top of a radiator. In a few weeks your potatoes will be covered with leafy sprouts on top and roots on the bottom
Before you plant sweet potato slips, you have a little extra work to do. Sweet potatoes need loose, well-drained soil to form large tubers. You don't want the roots to face resistance when they try to expand within the soil. Loose soil is more critical than almost any other factor when it comes to growing sweet potatoes successfully.