Potatoes do well when planted with beans, corn, cabbage, horseradish,  marigold and eggplant.

Potatoes do not do well near pumpkin, tomato, raspberry, squash and cucumber and sunflower.  The presence of these plants apparently lowers the potatoes' resistance to blight.

Beans with potatoes protect against Colorado potato beetles and the potatoes protect the bens against Mexican bean beetle.

Horseradish or flax in rows between potatoes protects against the potato bug and the blister beetle,  Flax improves both growth and flavour.

Nightshade weed attracts potato bugs, which eat the weed and die.  Nightshade is a member of the potato family. It has poisonous leaves, white flowers and black berries.

Hemp (Cannabis) grown in the neighborhood of potatoes helps protect against phytophthora infestans, the cause of late blight.  Dead nettle, nasturtium and esparsette growing near are thought to be of benefit.

Potatoes do well when they follow a rye crop.  Cabbages do well planted between potatoes after the first hilling.  The presence of lamb's quarters in the potato patch is an indication that the crop should be moved to a new location.

Colorado potato beetles are attracted to eggplant, preferring it to the potatoes. A border grown around the potatoes patch will serve as a trap crop to  catch and destroy the beetles.

Potatoes should not be grown near orach, tomatoes or apples. Apple trees cause potatoes to be more susceptible to phytophthora blight.

Under light, potatoes develop a green color and an poisonous alkaloidal glucoside know as solanine. These potatoes should not be used for food unless all green is carefully removed. 

Ripening apples should NOT be stored in the same cellar as potatoes since they give off small amounts of ethylene gas which can give the potatoes an off flavor and affect shelf life.  The apples, too, lose flavor in the presence of potatoes.