Sweet potatoes are storage roots from the plant Ipomoea batatas, a member of the morning glory family (Convolvulaceae). They are botanically distinct from white potatoes, which are stem tubers belonging to the nightshade family. Gardeners often use companion planting to maximize the health and productivity of their sweet potato crop. This technique involves strategically placing certain plants near one another to create a mutually beneficial micro-ecosystem. Selecting the right neighbors naturally enhances yields and manages common garden issues without relying on chemical interventions.
Why Companion Planting Benefits Sweet Potatoes
Companion planting establishes a balanced, supportive environment for sweet potato vines. A primary benefit is the natural management of garden pests through chemical signals or physical barriers. Certain aromatic plants release compounds that either mask the scent of the foliage or actively repel destructive insects. This method reduces the need for external pest controls, allowing the crop to develop undisturbed.
Although sweet potatoes require ample space, their aggressive ground cover benefits from strategic neighbors. Low-growing companion plants act as a living mulch, providing density that suppresses weed growth. Weed suppression conserves soil moisture and reduces competition for nutrients. Furthermore, specific companions can improve the soil’s chemical composition, directly supporting tuber development.
Ideal Companion Plants
Effective companion plants contribute essential nutrients or natural defense mechanisms to the sweet potato patch. Legumes, such as pole beans and cowpeas, fix atmospheric nitrogen into the soil. Bacteria in their root nodules convert nitrogen gas into a usable form. This nitrogen is released when the legume roots decompose, replenishing a nutrient sweet potatoes utilize heavily for vine growth.
Aromatic herbs and flowers serve as a defense system, particularly against the sweet potato weevil (Cylas formicarius). French marigolds release a substance from their roots that suppresses harmful nematodes and weevils in the soil. Planting herbs like thyme, catnip, or summer savory nearby helps to confuse or repel weevils and other insects with their strong essential oils.
Ground-covering plants and flowers offer physical benefits that regulate the garden environment. Sweet alyssum forms a dense, low mat that shades the soil, keeping the root zone cooler and suppressing weeds without competing heavily with the sweet potato roots. The tiny flowers of alyssum and borage attract beneficial insects, such as parasitic wasps and hoverflies, which prey on soft-bodied pests like aphids. Radishes are quick-growing root crops that help break up and aerate compacted soil, making it easier for developing sweet potato roots to expand.
Plants to Avoid When Growing Sweet Potatoes
Certain plants should be kept at a distance because they hinder the crop’s development or increase the risk of disease. Heavy feeders, like corn and members of the brassica family (broccoli and cabbage), demand significant soil nutrients. These plants quickly deplete the nitrogen and minerals sweet potatoes need, resulting in stunted vine growth and smaller tubers.
Competitive root crops pose a direct threat because they occupy the same subterranean space. True potatoes (Solanum tuberosum) compete directly with developing sweet potato roots for room and resources in the upper soil layers. This competition can lead to a reduced yield of both crops.
The most problematic companions share common pests and diseases, creating a “disease bridge” in the garden. Plants in the nightshade family, including tomatoes, peppers, and eggplant, are susceptible to similar fungal wilts and harbor the same pests. Planting tomatoes nearby increases the risk of spreading fungal pathogens and can attract the sweet potato weevil. Maintaining separation from these vulnerable plants reduces overall risk.