Potato Companion Plants

Claim. Beans are said to deter Colorado potato beetle, and potatoes to deter Mexican bean beetle. No controlled evidence was found for either direction.

Mechanism. Proposed by tradition; not demonstrated in a controlled comparison.

Conditions. Planted together Both plants must be present at the same time.

Applies when. Optional experiment, not a guarantee.

Limitations. Tradition only.

Evidence. Tier D: Traditional knowledge or structured community observations without a controlled comparison. (tradition).

Sources. University of Minnesota Extension 2023

Reviewed August 15, 2026 by Garden Planner editorial team (pending independent horticultural review). Record bush-beans--potato--pest_suppression v1. Request a correction.

Claim. Cucumbers and potatoes are traditionally kept apart, sometimes citing blight. Late blight of potato (Phytophthora infestans) does not infect cucumbers; no shared disease justifies the rule.

Mechanism. Claimed by tradition; no harmful interaction demonstrated.

Conditions. Planted together Both plants must be present at the same time.

Applies when. The planner does not separate these plants on this claim; it evaluates space, light, water and timing normally.

Limitations. No mechanism; the planner treats this as no verified relationship for risk purposes.

Evidence. Tier D: Traditional knowledge or structured community observations without a controlled comparison. (tradition).

Sources. University of Minnesota Extension 2023

Reviewed August 15, 2026 by Garden Planner editorial team (pending independent horticultural review). Record cucumber--potato--disease_risk v1. Request a correction.

Claim. Sunflowers are said to inhibit potatoes and beans through allelopathy. Laboratory bioassays show inhibitory compounds in sunflower residues, but a field effect on neighbours at normal spacing is not established; shade and water competition explain most reports.

Mechanism. Claimed by tradition; no harmful interaction demonstrated.

Conditions. Planted together Both plants must be present at the same time.

Applies when. The planner does not separate these plants on this claim; it evaluates space, light, water and timing normally.

Limitations. Lab evidence only.

Evidence. Tier D: Traditional knowledge or structured community observations without a controlled comparison. (tradition).

Sources. Duke 2015

Reviewed August 15, 2026 by Garden Planner editorial team (pending independent horticultural review). Record sunflower--potato--allelopathy v1. Request a correction.

Claim. Eggplant is a preferred host of Colorado potato beetle and shares soil-borne wilts with potato; adjacent plantings let beetles move between them.

Mechanism. Shared pest and pathogens within the nightshade family.

Conditions. Planted together Separate beds. Both plants must be present at the same time.

Management. Hand-pick beetles; Rotate nightshades together.

Applies when. Where Colorado potato beetle occurs (North America, Europe).

Limitations. Manageable trade-off; mainly a rotation issue.

Evidence. Tier C: Indirect evidence: greenhouse or pot work, a related crop or species, or credible extension guidance with important uncertainty. (extension synthesis).

Sources. University of California Statewide Integrated Pest Management Program 2025; University of Minnesota Extension 2023

Reviewed August 15, 2026 by Garden Planner editorial team (pending independent horticultural review). Record potato--eggplant--shared_pest v1. Request a correction.

Claim. Potatoes and strawberries share Verticillium wilt; avoid planting strawberries in beds that grew potatoes in the last three years.

Mechanism. Soil-borne pathogen.

Conditions. Planted together Separate beds. Both plants must be present at the same time.

Management. Keep bed history; Resistant cultivars.

Applies when. Rotation concern.

Limitations. Manageable.

Evidence. Tier C: Indirect evidence: greenhouse or pot work, a related crop or species, or credible extension guidance with important uncertainty. (extension synthesis).

Sources. University of Minnesota Extension 2023; Royal Horticultural Society 2025

Reviewed August 15, 2026 by Garden Planner editorial team (pending independent horticultural review). Record potato--strawberry--disease_risk v1. Request a correction.

Claim. Potato and tomato are both hosts of late blight; spores spread readily between adjacent plants, and infected potato foliage or volunteers are a common source of tomato infection. Extension services advise keeping them apart and rotating the nightshade group.

Mechanism. Shared pathogen with airborne spores; one crop acts as an inoculum source for the other.

Studied in. Extension and IPM guidance based on pathogen biology. (home garden)

Conditions. Planted together Separate beds; as far apart as the garden allows. Risk whenever both crops have foliage during wet, mild weather.

Management. Remove volunteer potatoes; Use resistant cultivars; Destroy infected foliage promptly.

Applies when. Serious in humid or wet-summer regions; a hard constraint in the planner wherever late blight occurs.

Limitations. In dry climates with no late blight history the risk is lower; they still share Colorado potato beetle and early blight.

Evidence. Tier B: One or more relevant controlled field studies or an authoritative synthesis tied to the crop, effect and arrangement. (extension synthesis).

Sources. University of Minnesota Extension 2023; University of California Statewide Integrated Pest Management Program 2025; University of Minnesota Extension 2023

Reviewed August 15, 2026 by Garden Planner editorial team (pending independent horticultural review). Record potato--tomato--disease_risk v1. Request a correction.

Claim. We did not find a source that establishes a benefit or harm between potato and corn.

Mechanism. None documented.

Conditions. Planted together Both plants must be present at the same time.

Applies when. The planner evaluates spacing, light, water and timing normally.

Limitations. No relationship documented; both are heavy feeders.

Evidence. Unknown: No source meeting the inclusion rules. (none).

Sources. University of Minnesota Extension 2023

Reviewed August 15, 2026 by Garden Planner editorial team (pending independent horticultural review). Record potato--corn--other v1. Request a correction.