What to Plant After Sweet Potatoes

Sweet potatoes (Ipomoea batatas) produce trailing vines and a thickened root that is edible, but not a potato. Plants are perennials when grown in U.S. Department of Agriculture plant hardiness zones 9 through 10 but are grown 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 in the same location in the garden two years in a row.

Growing Sweet Potatoes

Sweet potatoes are grown from slips, which are sprouts grown from stored tubers. You can plant slips in late spring once the soil has warmed to 70 degrees Fahrenheit, setting slips so that only stem tips and leaves are exposed. Space slips 1 foot apart, leaving 3 feet between rows. Harvest sweet potato tubers before the first frost, digging carefully to avoid bruising the roots. Do not plant sweet potatoes in the same area 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, do not plant sweet potatoes or other annual garden plants, such as tomatoes (Lycopersicon esculentum), potatoes (Solanum tuberosum) or eggplants (Solanum melongena) that are prone to root rot nematodes in an area of the garden where sweet potatoes grew the previous year. Root rot nematodes are impossible to detect with the naked eye, so look for other signs of their presence, such as knotted roots and poor foliage and tuber growth.

What You Can Plant

You can plant a green manure crop in an area where sweet potatoes have previously grown in the garden. You can also plant annual vegetables that are not prone to root rot nematodes, such as 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 manure is dug into the soil and plants other than those prone to root rot nematodes can be planted there for the next three 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 sure to remove all crop residue left behind in the sweet potato bed. Allelopathic chemicals can be present in leaves, fruits, flowers or stems of plants, so all sweet potato plant parts must be removed.

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