Companion Plants Potatoes grow better with good companion plants/intercrops. Greatest yield drop occurs during time up to tuber formation. So plant or set out intercrop a few weeks after potatoes are planted. Traditional ones are: bush beans and corn (3 potato pls to 1 corn/bean combo) with Mentha, or cabbage interspersed with Salvia, Calamintha, thyme, and rosemary. Some other more unusual plants that grow naturally with potato are Verbena, Tropaeolum, Senecio, Ipomoea (I. batatas, sweet potato) Calceolaria, Oxalis (watch out as several of these are invasive weeds), and Urtica (leaves sting; wear gloves when handling plant). For pest control, all plant species in the same row have worked better than separate rows. Also, other plants in the Solanaceae family such as tomatillo (Physalis), peppers (Capsicum), other species of Solanum such as eggplant, and tomato and planting several varieties of potato, also slow down the pests (attract them away from your favorite potatoes!). To attract insect predators/parasites , add diversity, and as trap crops, along the garden edges, just beyond the path encircling the garden, Datura (very pretty and very poisonous), annual Nicotiana (wild tobacco), Solanum umbelliferum, Solanum xanti, other non-weedy indigenous Solanum species, Berberis, Stipa (Nasella), Bidens, Cassia, Opuntia (edible pads), Astragalus (very poisonous to livestock), Baccharis, Lupine, and Stachys can be planted.
Here Beans and Potato are growing together, with Verbena in the upper left of photo. The heavy mulch of straw caused problems. Not because of the mulch, but because of the mice living under the thatch hut we made with the mulch.
If you're raising mice this is an excellent method. If not, use a thin layer of mulch. Better yet to compost the straw with animal/green manure, which saves nitrogen, and then add the finished compost as a thin mulch layer.