This document lists various plant companions and antagonists for several common garden vegetables. It notes that spinach grows well with strawberries, tomatoes like being planted with chives and onions, and that radishes and strawberries make good companions for lettuce. Squash and pumpkins grow well alongside corn, while beans, potatoes, and carrots are compatible but onions, garlic, and gladiola do not mix well with beans.

1. Companion Planting
Plant Companions Antagonists (don’t like)
spinach Strawberries
tomatoes Chives, onions, parsley, Kohlrabi, potatoes,
asparagus, marigold, fennel, cabbage
nasturtiums, carrots
lettuce Carrots with radishes,
strawberries,
cucumbers, onions
Squash (pumpkin) corn potato
radish Peas, lettuce,
cucumbers
onions Beets, strawberries, Peas, beans
tomatoes, lettuce,
summer savory,
chamomile, leeks,
parsley
corn Potatoes, peas, beans,
cucumbers, pumpkin,
squash
carrots Peas, leaf lettuce,
chives, onions, leeks,
rosemary, sage,
tomatoes
beans Potatoes, carrots, Onion, garlic, gladiola,
cucumbers, cauliflower, chives
cabbage, summer
savory, most other
vegetables and herbs