Sweet potatoes (Ipomoea batatas) are a warm-weather root crop grown for their nutrient-dense underground tubers. As a member of the morning glory family, the plant produces extensive vines that spread across the ground, requiring significant garden space. Companion planting involves growing specific plants near each other to create a mutually supportive environment. This practice maximizes garden health and productivity by improving soil conditions, attracting beneficial insects, and providing natural pest control.
Beneficial Companion Plants
Certain plants actively improve the health and yield of sweet potatoes. Legumes, such as bush beans and peas, are valued companions because they fix atmospheric nitrogen. They convert nitrogen gas into a usable form that enriches the soil, supporting the sweet potato’s leaf development.
Aromatic herbs and flowers offer defense against common pests, like the sweet potato weevil. Alliums (garlic and chives) release sulfur compounds that mask the sweet potato’s scent, confusing weevils and deterring aphids. Marigolds protect developing tubers by releasing chemicals that repel root-knot nematodes, microscopic worms that damage roots.
Flowers like nasturtiums and yarrow function by luring or hosting beneficial insects. Nasturtiums serve as a sacrificial trap crop, drawing aphids and flea beetles away from the vines. Yarrow attracts natural predators (ladybugs and lacewings) which prey on pests like spider mites and aphids. This biological control reduces the need for chemical intervention.
Neutral Neighbors and Space Utilization
Sweet potatoes have sprawling vines and deeply set tubers, competing for surface space and nutrients. Selecting neutral neighbors maximizes garden density without causing competition for sunlight or water. These plants typically occupy a different vertical or subterranean layer.
Root crops with shallow systems, such as radishes and beets, can be planted early alongside sweet potato slips. These crops mature and are harvested before the sweet potato vines fully cover the ground. This utilizes a shallow soil layer that the sweet potato tubers do not need until much later.
Tall, upright crops like corn or trellised pole beans can also be intercropped successfully. These vertical growers occupy the air space above the sweet potato’s canopy, avoiding competition for ground-level light. The sweet potato vines can spread between the upright crops, benefiting from partial shade during the hottest parts of the day. Leafy greens, such as spinach or lettuce, can be planted close to the surface, acting as a living mulch that suppresses weeds and keeps the ground cool.
Plants That Inhibit Sweet Potato Growth
Certain plant pairings should be avoided because they threaten the sweet potato’s health or compete too heavily for resources. Plants that share susceptibility to the same diseases or pests can act as a reservoir for infection. The Solanaceae family, including true potatoes, tomatoes, and eggplant, should not be planted nearby because they share common soil-borne pathogens and attract similar insect pests.
The primary risk is the transmission of fungal diseases like Fusarium wilt or Verticillium wilt, which persist in the soil. Planting members of the nightshade family nearby perpetuates the cycle of these diseases, contaminating the soil for future plantings. Additionally, high-water-demand crops that are heavy nutrient feeders will directly compete with the sweet potato’s extensive root system.
Vigorous, sprawling cucurbits like squash, pumpkins, and melons should also be kept separate due to their extensive vining habits. These plants compete directly for sunlight and surface space, leading to poor air circulation and reduced tuber development. This competition can severely stunt the sweet potato’s growth.