Sweet potatoes are a staple in warm weather climates of the southern United States, South America and Africa. The gorgeous green leaves of the sweet potato vine grace hanging baskets every year as a trailing plant, but you can grow them as more than an ornamental plant. These root vegetables do well here in Chicago if you plant them at the right time in well-drained soils.
Here in the Midwest, planting of sweet potatoes should wait well until June when the soil is heated to over 70 degrees. These plants have tropical origins, so they need heat and good watering to survive. However, if your soil is too clay-heavy, the roots will rot if they sit in water too long. Make sure that you are planting in loose soil that has been amended or is in a raised bed.
There are many kinds of sweet potatoes - vining for those who have more space and vineless for those with little. There are over 12 varieties that are easily available, mostly from mail order catalogs or online retailers. They are available for purchase as plants, or "slips" as they are often called. Just like it's barely botanically related "other" the potato, there are many more varieties available to grow than can be bought in most grocery stores.
Once you plant in early June, expect to be able to harvest in the early to late fall. If you have small sweet potatoes at harvest time, you can save them in a cool, dry place over the winter (just like potatoes!) and use them to start your own slips to be planted outside next season.
Please add your techniques or growing tips in the comments section, below.