Sweet potatoes (Ipomoea batatas) create tracking vines and a thickened root that is edible, although not a potato. Plants are perennials when developed in U.S. Department of Agriculture plant hardiness zones 9 through 10 but have been increased in all zones as warm-season garden annuals. Sweet potatoes are easy to grow and tolerant of drought and heat; however, you should not grow sweet potatoes at precisely the same location in the backyard two years in a row.
Growing Sweet Potatoes
Sweet potatoes have been grown by slips, which can be grown from tubers that were stored. You can plant slips in late spring when the soil has heated to 70 degrees Fahrenheit, placing slips so that only stem leaves and tips are vulnerable. Space slips 1 foot apart, leaving 3 feet between rows. Harvest sweet potato tubers prior to the first frost, stirring carefully to avoid bruising the roots. Don’t plant potatoes at precisely the same place the following year to prevent the buildup of disease.
Avoiding Disease with Crop Rotation
Sweet potatoes are prone to attacks by root rot nematodes. For this reason, don’t plant sweet potatoes or other yearly garden plants, like tomatoes (Lycopersicon esculentum), potatoes (Solanum tuberosum) or eggplants (Solanum melongena) that tend to root rot nematodes within an area of the backyard where sweet potatoes grew the previous season. Root rot nematodes are not possible to find with the naked eye, therefore look for other signs of the presence, like knotted roots and inadequate foliage and tuber development.
What You Can Plant
You can plant a green manure crop in an area where sweet potatoes have previously grown in the backyard. It is also possible to plant annual vegetables that aren’t prone to root rot nematodes, like lettuce (Lactuca sativa), spinach (Spinacia oleracea) and cabbage (Brassica oleracea var. capitata). A green manure crop is grown and incorporated into the soil immediately after flowering or while still green. The green mulch is dug into the dirt and plants aside from those prone to root rot nematodes can be planted there for the next 3 seasons.
Sweet Potato Residue
Sweet potatoes release an allelopathic chemical during decomposition that can prevent seed germination in the soil surrounding them. Before planting any other seeds in an area where sweet potatoes have previously grown, make certain to eliminate all harvest residue left behind in the sweet potato mattress. Allelopathic chemicals can be present in leaves, fruits, flowers or stems of plants, therefore all sweet potato plant components have to be eliminated.