I bought an organic sweet potato to enjoy for lunch and then forgot to eat it. It sat in our fruit bowl for a few weeks before I noticed all the little green sprouts. I hacked it in half and suspended it over a glass of water with tooth picks with just a little bit of the potato in the water. After a week it looked like this:
After the shoots got to be about 8-10 inches tall I gently pulled them off of the potato and put them into a jar of water where they quickly grew roots.
After two more weeks the roots had filled up the glass jar. I filled up a pot with potting mix and plopped them in there. Now I have a big beautiful pot of sweet potato vines growing on the deck. Give them a big enough pot (or plant them directly into the garden) and you'll have sweet potatoes by fall. Great thing about all this? That one sweet potato keeps on producing sprouts endlessly. I could fill the deck with greenery very inexpensively. Just make sure you start with an organic sweet potato, the traditionally grow ones are sprayed to prevent sprouting. Happy gardening!