Noel Valdes presented a program about growing sweet potatoes at the March 24, 2016 Dodge County Master Gardener meeting. Sweet potatoes are actually morning glories! They produce a beautiful bloom and all parts are edible and non-toxic including the leaves and stems. Warm climate conditions are required for most sweet potatoes, but new varieties have been developed for our Wisconsin climate and shorter growing season.
Many local nurseries and greenhouses have the sweet potato slip varietal called Jewel, developed for northern climates. You can also obtain cuttings from any part of a sweet potato if you know someone who has had success with growing them locally. The best way to grow sweet potatoes is either in a raised bed or in ridged hills, but in the ground works too. Planting must absolutely wait until after our last frost; sweet potatoes are frost intolerant. Using soil warming plastic much enhances growth and eliminates a lot of weeding.
Sweet potatoes should be rooted deeply, 9-12″ and 18 to 24 inches apart. They need a lot of room to grow. Once planted and leafing out occurs, your crop will require very little maintenance. The only pests are wire worms, voles and deer. Use a row cover or agricultural fabric to protect plants.
At harvest, this must occur before the last frost, use loppers to cut off the vines to the ground. Sweet potatoes in the ground are very fragile so leave lots of room around and under the fruit when digging to prevent damage. Cure the potatoes for 10 days at 70˚, wrap them in newspaper and your sweet potatoes are good for one year.