Buying bundles of sweet potato slips can be very pricey, especially if you are a pathologically cheap tightwad like me. Many sweet potatoes in grocery stores have been treated with growth inhibitors and so can very reluctant to sprout. I buy mine at health food stores, where frequently they have leafy shoots emerging already. I usually cut one into several chunks, each with a shoot on it, let it dry in the shade for a day to heal, then bury each about 4 inches deep. The shoots emerge about a week later. Each summer I grow 'Garnet', 'Puerto Rico Gold' and a mystery one I got from a Filipino neighbor years ago I call "Filipino White". It is VERY vigorous and makes vast quantities of the leaves that are a wonderful spinach substitute when cooked....more nutritious than spinach and no oxalic acid. It roots VERY easily from stem cuttings in water. The white sweet potatoes are produced in extreme abundance and are less sweet than the usual types. The leaves of all types of sweet potatoes are yummy cooked, and some folks like them raw in summer salads. I always had poor results with sweet potatoes in Denver as those chilly nights were hard on this heat-loving tropical member of the Morning Glory family (Ipomaea batatas). But here in Florida and other places with long hot summers with warm nights, they are super-productive. The pic of a harvest between my feet shows just how many sweet potatoes you can get from just ONE rooted chunk!