Sweet potatoes are botanically different from white potatoes. Sweet potatoes (Ipomoea batatas) are in the morning glory family while white potatoes (Solanum tuberosum) are in the nightshade family. Both produce tubers but sweet potatoes are planted in the summer and harvested in the fall, while white potatoes are planted in the early spring and harvested in the summer. Sweet potatoes need a long growing season, at least 4 months, and thrive in our hot and humid summers here in the DC metro area.
While white potato plants are started with chunks of the tuber, sweet potatoes are grown from rooted sprouts called slips. Slips may look like limp, short stems with no roots. If you order slips, plant them when the soil has warmed to at least 60 degrees and nighttime temperatures are above 60 degrees. If it is too cold, pot them up and hold them inside near a sunny window.
Plant slips about a foot part, covering with soil up until the first pair of leaves. These plants are usually grown in the ground, in loose, well-drained soil. These plants are vines that grow several feet long so give them plenty of space. The green, heart-shaped leaves are edible (deer like them too). The plants will grow up until frost and the tubers should be harvested before the first heavy frost.
Ornamental sweet potato plants are grown for beautiful foliage in a wide range of colors. Ornamental sweet potato plants can have chartreuse, dark purple, bronze-red, mahogany red, or variegated cream, green, and red colored leaves. These are used frequently in containers in public spaces and gardens because the vines are ideal “trailers,” draping over containers. Since they are tropical plants, they tolerate our hot summers and add quite a lot of color. These are easy to find at local garden centers and are sold as small annuals in cell packs.
There is a relatively new line of sweet potato plants that have beautiful ornamental foliage (still edible) and produce tubers for harvest. Treasure Island Sweet Potatoes have been bred by Louisiana State University AgCenter from an original concept development and collaboration work by their partner FitzGerald Nurseries in Ireland. These plants can be grown in a container in the summer for colorful leaves and the tubers can be harvested in the fall. The plants in the Treasure Island series are named after different Polynesian Islands because each plant “hides” a treasure underneath the soil.
There are five plants:
Tahiti, green leaves and purple tubers
Tatakoto, dark green purple leaves and orange tubers
Makatea, golden green foliage and white tubers
Kaukura, purple foliage and orange tubers
Manihi, dark purple foliage and orange tubers.
These new plants would make an ideal children’s gardening project and vegetable container plant for those with limited space.
Either way you slice it, sweet potatoes are great additions for the garden. Try growing some this year!