What Are the Best Companion Plants for Potatoes?

Potatoes occupy the ground from late spring to midsummer and produce a lot of foliage. They are vulnerable to late blight, aphids that spread virus diseases, Colorado potato beetle (in some regions), and wireworm. Companion planting can reduce aphid pressure and deter some pests, but blight control relies primarily on variety choice, good drainage, and crop rotation. Know what companions can and cannot do before you plant.

Horseradish at the Corners

Horseradish planted at the corners of a potato bed is a traditional companion that appears to improve the general health and resistance of nearby potato plants. The mechanism is not fully understood, but horseradish contains glucosinolates that break down to allyl isothiocyanate in the soil — a compound with antibacterial and antifungal properties. Growing horseradish at the corners rather than interplanted avoids the risk of horseradish taking over the bed, as it spreads vigorously. Mark the roots carefully because horseradish is extremely difficult to eradicate once established.

Marigolds Against Nematodes

Root-knot nematodes can cause serious damage to potato tubers, creating small cysts and deforming the crop. French marigolds (Tagetes patula) planted as a cover crop in the bed the previous season, or densely interplanted, release alpha-terthienyl from their roots, which kills nematode larvae in the soil. This is one of the most evidence-backed companion interactions available. For it to be effective you need a dense planting — a border of marigolds around the bed is less effective than marigolds grown throughout it the year before potatoes go in.

Basil and Tansy for Insect Deterrence

Basil planted alongside potatoes appears to repel aphids, particularly the potato aphid which is a vector of potato leaf roll virus. Dense plantings of basil around the perimeter of the potato bed create an aromatic barrier. Tansy, a strongly aromatic herb, has been used traditionally to deter Colorado potato beetle and has some supporting evidence. Plant it in clumps at the edges of the bed — tansy spreads and needs to be managed, but its aromatic properties make it useful in appropriate quantities.

Beans for Nitrogen

Climbing or dwarf beans planted between potato rows fix nitrogen at their roots which benefits the surrounding soil. Beans and potatoes occupy different soil depths — beans' fine surface roots versus the deeper potato tubers — so competition is limited. The combination of a nitrogen-fixer with a heavy-feeding root crop is a sound agricultural pairing. In small gardens this also improves space efficiency because beans can be trained upward while potatoes spread outward.

What to Keep Away from Potatoes

Tomatoes, peppers, aubergines, and other members of the Solanaceae family must not be planted next to or after potatoes. They share late blight (Phytophthora infestans), early blight, and other diseases. Growing them together concentrates and amplifies those disease risks. Cucumbers and squash should also be kept away because they can increase aphid populations that then migrate to potatoes. Fennel is harmful to most vegetables and should be isolated from the entire kitchen garden.