Sweet Potato Companion Plants

Sweet potato companion plants

The best sweet potato companion plants are marigolds, nasturtiums, thyme, and summer savory. These companions deter pests, attract beneficial insects, and work without competing with sweet potato vines for space. The worst companions are other vining crops, large-rooted vegetables, and plants from the morning glory family.

Sweet potato companion planting is straightforward once you understand the plant’s main challenges: aphid pressure on vines, nematode damage to roots, and the aggressive spread of vines that crowds out nearby plantings. The best companions address one or more of these challenges without creating new ones.

Why companion planting works for sweet potatoes

Sweet potatoes face consistent pest pressure across the US:

• Aphids attack vines, especially in hot weather
• Sweet potato weevil (primarily in Zone 8+ southern states) damages roots
• Root-knot nematodes cause galled, misshapen roots in southern soils
• Colorado potato beetle occasionally attacks foliage in northern states
• Whiteflies can colonize vines in warm climates

Companion plants address these pests through several mechanisms:

1. Trap cropping: Drawing pests to sacrifice plants (nasturtiums for aphids)
2. Aromatic deterrence: Strong-smelling plants disrupt pest navigation (thyme, marigolds)
3. Beneficial insect habitat: Providing nectar for parasitic wasps and predatory beetles that control pests
4. Soil biology: Marigolds secrete compounds toxic to root-knot nematodes

Best companion plants for sweet potatoes

Marigolds

The most well-documented and widely recommended companion for sweet potatoes.

French marigolds (Tagetes patula) secrete alpha-terthienyl from their roots — a compound toxic to root-knot nematodes in the soil. Studies at NC State and the University of Florida have confirmed that marigold plantings reduce nematode populations in adjacent soil.

For sweet potatoes, this matters: root-knot nematodes cause significant yield losses in southern states (Zone 7–10), where the nematodes remain active year-round. A border of French marigolds on all sides of the sweet potato bed provides protection throughout the season.

Additional benefits:

• Strong scent deters aphids and may deter sweet potato weevil
• Bright flowers attract beneficial insects including parasitic wasps
• Easy to grow as a summer annual alongside sweet potatoes in the same season

Best varieties: ‘Petite Harmony’, ‘Lemon Drop’, ‘Naughty Marietta’ (French marigold types). Avoid giant African marigolds — too tall to border a bed without shading vines.

See our marigolds guide for planting and care details.

Nasturtiums

Nasturtiums are the best trap crop for aphids — one of the most common sweet potato pests.

Aphids strongly prefer nasturtiums over sweet potato vines. A planting of nasturtiums near sweet potatoes draws aphid populations away from vines while also providing habitat for beneficial insects. Parasitic wasps that lay eggs in aphids are attracted to the nectar-rich nasturtium flowers.

Additional benefits:

• Edible flowers and leaves (peppery, excellent in salads)
• Sprawl low and won’t shade vines if planted at the edge
• Reseeds readily in warm climates for minimal annual effort

Potential drawback: A heavily infested nasturtium can host enough aphids to migrate to sweet potatoes if left unmanaged. Check trap plants weekly and remove heavily infested growth.

See our nasturtium growing guide for care and uses.

Thyme and oregano

Aromatic herbs may deter sweet potato weevil and aphids through volatile compounds.

Thyme (Thymus vulgaris) and oregano (Origanum vulgare) are planted near sweet potatoes primarily for their strong scents, which may disrupt pest navigation. The evidence is more observational than controlled, but both plants serve multiple purposes — edible herbs for the kitchen and flowering plants that attract beneficial insects in summer.

Plant thyme and oregano at the edge of the sweet potato bed rather than between rows — they stay small enough not to interfere with vine sprawl, and their woody stems survive being occasionally covered by vines.

For care details, see our creeping thyme guide and Greek oregano guide.

Summer savory

Summer savory (Satureja hortensis) is less commonly known but effective. Its strong scent deters several soft-bodied insects including aphids and may deter sweet potato weevil in southern states. It grows to 12–18 inches and provides edible harvests of strongly flavored leaves used in bean and vegetable dishes.

Beans

Bush beans at the edge of a sweet potato bed provide nitrogen fixation without competing with vines.

Beans fix atmospheric nitrogen through root bacteria, enriching the soil. Sweet potatoes are moderate feeders and benefit from nitrogen enrichment without the application of synthetic fertilizers.

Important: Do not plant beans in the path of sweet potato vines. Sprawling vines will cover and smother low-growing beans within a few weeks. Plant beans at the bed margin, giving them at least 24 inches of space from the nearest sweet potato slip.

Pole beans planted before sweet potato slips are set out can work if given a head start — but pole beans need full sun too, and competing with sweet potato vines in a cramped bed usually doesn’t end well.

Tansy

Tansy (Tanacetum vulgare) has a long history as an insect-repelling plant. It is aromatic and may deter several sweet potato pests. Important note: tansy is toxic if ingested (humans and livestock) and spreads aggressively by seed. Deadhead flowers before they set seed, or choose non-seeding varieties. Plant at the bed edge only.

Summer flowers

Many annual flowers serve as beneficial insect habitat when planted near sweet potatoes:

• Zinnias attract hummingbirds and parasitic wasps
• Cosmos attract beneficial insects through the summer season
• Alyssum provides nectar for small parasitic wasps that control caterpillar pests

The primary value of these flowers is supporting beneficial insect populations across the whole garden, not specific sweet potato pest deterrence.

Companion plants comparison

What not to plant near sweet potatoes

Squash and other vining crops: Both sweet potatoes and squash spread aggressively by vining. Planted near each other, they compete for space and the same soil resources. The sweet potato vine usually loses — squash vines are larger and move faster early in the season.

Potatoes and tomatoes: These share diseases with sweet potatoes — particularly fungal diseases like early blight and some root rots. Keep them in separate parts of the garden.

Sunflowers: Sunflowers produce allelopathic compounds from their roots that inhibit the growth of some nearby plants. Sweet potatoes grown near sunflowers sometimes show reduced yields. The evidence is observational, but the risk is easy to avoid by keeping sunflowers at distance.

Morning glory and bindweed: Sweet potatoes and ornamental morning glories are both in the Ipomoea genus — they share some pests and diseases. Bindweed (Convolvulus arvensis), though in a different genus, is a persistent weed that competes aggressively. Keep all morning glory relatives away from sweet potato beds.

Tall crops that shade vines: Sweet potatoes need full sun (6+ hours daily). Corn, tall sunflowers, and large tomato plants cast shade that reduces yield. Plant these well away from sweet potato beds.

Companion planting in practice

How to set up a companion-planted sweet potato bed:

1. Plan the bed with sweet potato slips in the center, companion plants around the perimeter
2. Plant French marigolds along the entire perimeter, 6 inches inside the bed edge
3. Plant nasturtiums outside the marigold border — they serve as the outermost trap crop
4. Place thyme or oregano at corners of the bed
5. Set sweet potato slips in the center, 12–18 inches apart in rows 3 feet apart

The perimeter strategy uses companion plants as a barrier without putting anything directly in the path of sweet potato vines, which can reach 6–10 feet by midsummer.

For the broader principles of what grows well together, see our companion planting guide and companion planting chart.

Sweet potato care through the season

Companion planting works best when the sweet potato crop itself is healthy and well-managed.

Key growing requirements:

• Full sun (6+ hours daily) — essential for good yield
• Warm soil — 65°F minimum for slip planting
• Consistent moisture — drought stress reduces yield significantly
• Loose, well-drained soil — heavy clay compresses roots and causes misshapen tubers
• Season length — sweet potatoes need 90–120 days from planting to harvest

For complete sweet potato growing information including soil preparation, slip planting, curing, and storage, see our how to grow sweet potatoes and sweet potato growing guides.

NC State Cooperative Extension’s sweet potato production resources provide detailed pest management information for southern states where sweet potato weevil is a significant challenge.

Rotating sweet potatoes in the garden

Companion planting reduces pest pressure within a season, but crop rotation provides protection across seasons.

Do not plant sweet potatoes in the same bed two years in a row. Rotate with:

• Legumes (beans, peas) — improve soil nitrogen
• Brassicas (broccoli, cabbage, kale) — clean up different pests
• Alliums (onions, garlic) — suppress soil diseases

Returning to the same bed after 3–4 years allows nematode and disease populations to decline naturally. Marigold plantings during the off-year rotation period help suppress nematodes further.

Companion planting is one tool in a broader approach. Combined with rotation, good soil management, and variety selection, it consistently reduces pest pressure without chemical inputs.